JP2010206258A - Digital broadcast receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital broadcast receiver which has a power saving effect in a state where the receiver does not output specific digital broadcast signals and which outputs the digital broadcast signals promptly without the feeling of incompatibility when switching to the digital broadcast signals. <P>SOLUTION: In a state A, full-segment broadcasting is decoded and output. At the time, in the processing system of one-segment broadcasting, an IDR picture is detected from the stream of the one-segment broadcasting and the stream on and after the detection is preserved in a buffer. When the next IDR picture is detected, the stream is updated to the previous latest stream. When the full-segment broadcasting is switched to the one-segment broadcasting (state B), the stream preserved in the buffer is decoded from the first IDR picture and displayed at a display portion. Thus, the need of searching the IDR picture from the one-segment broadcasting when it is switched is eliminated and the decoding of the stream preserved in the buffer is immediately started. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a digital broadcast receiver, and more particularly to a digital broadcast receiver capable of selecting and outputting a plurality of image sources including a digital broadcast.

  FIG. 25 is a diagram for explaining the outline of digital terrestrial broadcasting, and shows the structure of a broadcast signal for one channel of terrestrial digital. The One Seg (one segment) broadcasting service is a service for mobile terminals that uses one segment of terrestrial digital television broadcasting waves, and the TS (Transport Stream) that constitutes the service is only one segment centered on the frequency of the broadcasting channel. Assigned to be transmitted in For this reason, the TS of the one-segment broadcasting signal can be reproduced by partially receiving the central portion of the broadcast wave of terrestrial digital broadcasting with a bandwidth of one segment.

Full segment (full segment) broadcast is a broadcast service mainly for fixed receivers, and HD (High-Definition) programs using 12 segments different from the one-segment broadcast segment are broadcast. There is also a form in which four segments of SD (Standard Definition) are broadcast simultaneously for two to three programs.
In the one-segment broadcasting service and the full-segment broadcasting HD service, the same program is usually broadcast by simultaneous broadcasting. When a plurality of SD programs are broadcast by full-segment broadcasting, the same program as one of the plurality of SD programs is broadcast by one segment by simul.

  In digital broadcasting, radio communication by OFDM (Orthogonal Frequency-Division Multiplexing) is performed. As a modulation method, QPSK (Quadrature Phase Shift Keying) is generally used for one-segment broadcasting, and 64 QAM (Quadrature Amplitude Modulation) is used for full-segment broadcasting. Used. As the image encoding system, H.264 / AVC (Advanced Video Coding) is used for high-efficiency compression encoding at a limited transmission rate in one-segment broadcasting, and MPEG (Moving) is used in full-segment broadcasting. Picture Experts Group) -2 is used. As an audio encoding method, MPEG-2 AAC (Advanced Audio Coding) is used for both one-segment broadcasting and full-segment broadcasting.

  A terminal device such as a mobile phone is generally capable of receiving one-segment broadcasting. For example, in a terminal device such as a car navigation system, both full-segment broadcasting and one-segment broadcasting can be received, and when the reception status deteriorates while receiving full-segment broadcasting with high quality video and sound quality, transmission errors are higher than with full-segment broadcasting. There are also products that are designed to switch to one-seg broadcasting, which is more robust.

  In this way, in a digital broadcast receiver that can receive both one-segment broadcasting and full-segment broadcasting, if the reception state deteriorates when receiving and outputting full-segment broadcasting, the digital broadcasting receiver switches to one-segment broadcasting that is broadcast on simulcast. There is something. In this case, full-seg broadcasting has higher image quality and higher sound quality than one-seg broadcasting, requires a high CN (Career to Noise), and uses 64QAM as a modulation method, so that errors during transmission are likely to occur. . Therefore, when the reception state of the full segment broadcast is deteriorated due to the reception environment or the like during the output of the full segment broadcast, the output is switched to the one segment broadcast with low image quality and low sound quality but low required CN and less error. By switching from full-segment broadcasting to one-segment broadcasting in accordance with such a reception state, it is possible to continue program display and audio output without interruption of the received program even if there is some degradation in quality.

  On the other hand, terminal devices that support one-segment broadcasting and full-segment broadcasting are expected to be applied to small portable devices such as cellular phones in the future. In most cases, such a terminal device is driven by a built-in battery.

  For example, Patent Document 1 discloses a power saving technique for a digital broadcast receiver that decodes a digital broadcast signal according to a clock. This digital broadcast receiver includes control means for controlling clock supply using movement state data corresponding to the movement state of its own apparatus. This control means decodes and outputs the full-segment broadcasting TS when the apparatus is not moving, and outputs the one-segment broadcasting TS by switching to reception of the one-segment broadcasting when moving. As a result, the power required for decoding full-segment broadcasting can be reduced.

  Patent Document 2 describes a problem that occurs when viewing of 1Seg broadcasting is interrupted in a mobile communication terminal having a viewing function of 1Seg broadcasting, reducing power consumption and quickly returning to viewing of 1Seg broadcasting. There has been disclosed a portable communication terminal intended to achieve both. When the viewing of the one-segment broadcasting is interrupted, this mobile communication terminal gradually releases hardware resources for viewing the one-segment broadcasting over time. Here, since the opening is partial and stepwise, even when returning to the viewing of the one-segment broadcasting, only the released part needs to be returned, and a quick return can be realized. In addition, the power saving effect will be further enhanced as the opening progresses with the passage of time, and if the hardware does not return to 1Seg broadcasting even after considerable time has elapsed, all the hardware for viewing the 1Seg broadcasting will operate. Set to the stop state.

JP 2007-68020 A JP 2007-104490 A

  In a digital broadcast receiver capable of switching between full-segment broadcasting and one-segment broadcasting as described above, for example, when switching from full-segment broadcasting to one-segment broadcasting, a key frame is searched from the TS stream, and decoding is performed from the key frame. Need to start. A key frame is a picture that can be decoded independently. In MPEG-2, which is applied to full-segment broadcasting, an I picture corresponds to H.264 that is applied to one-segment broadcasting. In H.264 / AVC, IDR pictures are applicable. For example, in the standard of digital terrestrial broadcasting, the transmission interval of IDR pictures is determined to be 2 to 5 seconds, and is operated so as to be transmitted at intervals of about 2 seconds by a broadcasting station, for example.

  For example, when the transmission interval of IDR pictures is 2 seconds, starting the search for IDR pictures from the time when switching from full-segment broadcasting to one-segment broadcasting will take up to about 2 seconds until the first IDR picture is obtained. Further delays may occur due to synchronization.

  As described above, the digital broadcast receiver disclosed in Patent Document 1 decodes and outputs a full-segment broadcasting TS when the device is not moving, and switches to reception of one-segment broadcasting when the device is moving. Broadcast TS is output. In such a configuration, the operation of the decoder for decoding the one-segment broadcast is stopped when the full-segment broadcast is being output, so that a prompt display cannot be performed when the full-segment broadcast is switched to the one-segment broadcast.

  In Patent Document 2, when the viewing of the one-segment broadcasting is interrupted, hardware resources for viewing the one-segment broadcasting are gradually released over time. Low power saving effect. In addition, if hardware resources are released over time, there is a problem that prompt display cannot be performed when returning to one-segment broadcasting.

  In addition, for example, in a mobile terminal device having a reception function for one-segment (or full-segment) broadcasting and a function for operating an application such as e-mail, a screen generated by an application such as e-mail while viewing one-segment broadcasting After switching to, when returning to watching 1Seg broadcasting again, if the decoding system of 1Seg broadcasting is stopped while the application screen is displayed, a power saving effect can be obtained, but prompt return to 1Seg broadcasting is possible. There is also a problem that it will not be possible.

  The present invention has been made in view of the above circumstances, and outputs a digital broadcast signal in a digital broadcast receiver capable of selecting and outputting an image source from a plurality of image sources including a digital broadcast signal. It is an object of the present invention to provide a digital broadcast receiver that can obtain a power saving effect in the absence of a signal and can output the digital broadcast signal promptly without a sense of incongruity when switching to the digital broadcast signal.

  In order to solve the above-mentioned problem, the first technical means of the present invention selects either one of means for receiving and decoding a digital broadcast signal and at least a plurality of types of image sources including the decoded digital broadcast signal. A digital broadcast receiver provided with a means for outputting a digital broadcast signal that is received and selected as one of a plurality of types of image sources and is not selected as an output target It has means for detecting and storing a key frame that can be decoded independently from the signal stream, and when the selection of the output target is switched to a digital broadcast signal, the stored key frame is used for output. It is characterized by that.

  According to a second technical means, in the first technical means, the means for receiving and decoding the digital broadcast signal includes a tuner unit for selecting the digital broadcast, and a demodulating unit for demodulating the digital broadcast selected by the tuner unit. A decoding unit that decodes the demodulated digital broadcast signal, the decoding unit detecting a key frame from the input digital broadcast signal stream, and a key detected by the key frame detection unit A frame memory that decodes and stores the frame while updating the frame to the latest key frame in time, and stores the decoded key frame stored in the frame memory when the output target is switched to the digital broadcast signal Is read and output, and if the next key frame is detected from the selected digital broadcast signal during output, the next key frame is Is obtained is characterized in that decodes and outputs the stream.

  According to a third technical means, in the first technical means, the means for receiving and decoding the digital broadcast signal includes a tuner unit for selecting the digital broadcast, and a demodulator for demodulating the digital broadcast selected by the tuner unit. A decoding unit that decodes the digital broadcast signal demodulated by the demodulation unit, the decoding unit detecting a key frame from the stream of the digital broadcast signal, and a key frame detected by the key frame detection unit. Including a buffer that stores the stream that has not been decoded, from the key frame detected from the stream of the digital broadcast signal until the stream immediately before the next key frame detected in time is not decoded. Save to the buffer, and update the stream to be saved in the buffer so that it is always the stream immediately before the latest key frame. And, when the selection of the output target is switched to the digital broadcast signal, it reads a stream including the key frames stored in the buffer, in which is characterized in that decodes and outputs.

  According to a fourth technical means, in the first technical means, the means for receiving and decoding the digital broadcast signal includes a tuner section for selecting the digital broadcast, and a demodulation section for demodulating the digital broadcast selected by the tuner section. A decoding unit that decodes the digital broadcast signal demodulated by the demodulation unit, the decoding unit detecting a key frame from the stream of the digital broadcast signal, and a key frame detected by the key frame detection unit. A buffer that saves the latest keyframes while not being decoded, and when the output target is switched to a digital broadcast signal, the keyframes saved in the buffer are read, decoded, and output When the next key frame is detected from the selected digital broadcast signal during output, the next key frame is decoded and output. It is obtained by the features.

  According to a fifth technical means, in the first technical means, the means for receiving and decoding the digital broadcast signal includes a tuner section for selecting the digital broadcast, and a demodulating section for demodulating the digital broadcast selected by the tuner section. A decoding unit that decodes the digital broadcast signal demodulated by the demodulation unit, the decoding unit detecting a key frame from the stream of the digital broadcast signal, and a key frame detected by the key frame detection unit. Including a buffer that stores the stream that has not been decoded, from the key frame detected from the stream of the digital broadcast signal until the stream immediately before the next key frame detected in time is not decoded. Save to the buffer, and update the stream to be saved in the buffer so that it is always the stream immediately before the latest key frame. When the output target is switched to the digital broadcast signal, the stream including the key frame stored in the buffer is read, decoded while being fast-forwarded, output, and the buffer is empty and then selected. The digital broadcast signal stream is decoded and output.

  According to a sixth technical means, in the first technical means, the means for receiving and decoding the digital broadcast signal includes a tuner unit for selecting the digital broadcast, and a demodulator for demodulating the digital broadcast selected by the tuner unit. A decoding unit that decodes the digital broadcast signal demodulated by the demodulation unit, and the decoding unit detects a key frame from a stream of the digital broadcast signal, and a key frame detected by the key frame detection unit. Including a buffer that stores the stream that has not been decoded, from the key frame detected from the stream of the digital broadcast signal until the stream immediately before the next key frame detected in time is not decoded. Save to the buffer, and update the stream to be saved in the buffer so that it is always the stream immediately before the latest key frame. Then, when the output target is switched to the digital broadcast signal, the decoding unit reads the stream including the key frame stored in the buffer and performs a decoding process faster than the decoding performed by the decoding unit during normal output. And the stream of the selected digital broadcast signal is decoded and output after the buffer becomes empty.

  A seventh technical means is a digital broadcast receiver comprising means for receiving and decoding a digital broadcast signal, and means for selecting and outputting at least one of a plurality of types of image sources including the decoded digital broadcast signal The means for receiving and decoding the digital broadcast signal includes a tuner for selecting the digital broadcast, a demodulator for demodulating the digital broadcast selected by the tuner, and a digital broadcast signal demodulated by the demodulator. The decoding unit can be decoded independently from the stream of the selected digital broadcast signal when the selection of the output target is switched from one of a plurality of types of image sources to the digital broadcast signal. Key stream is detected, the digital broadcast signal stream is decoded from the detected key frame and output, and the digital broadcast signal stream is decoded. Until one of the multiple types of image source is maintained, and when the stream in which the digital broadcast signal is decoded is decoded, the output from one of the multiple types of image source is switched to the digital broadcast signal. It is a feature.

  The eighth technical means receives the one-segment broadcast signal assigned to the one segment in the frequency band as means for receiving and decoding the digital broadcast signal in any one of the first to seventh technical means. It has means for decoding and means for receiving and decoding a multi-segment broadcast signal using a plurality of segments, and switching from a multi-segment broadcast signal to a one-segment broadcast signal is a switching of selection of an output target It is characterized by.

  A ninth technical means receives a one-segment broadcast signal assigned to one segment in a frequency band as means for receiving and decoding a digital broadcast signal in any one of the first to seventh technical means. Has multiple decoding means, or has multiple means to receive and decode multiple segment broadcast signals using multiple segments, and outputs switching between one segment broadcast signals or switching between multiple segment broadcast signals This is characterized in that the selection of the object is switched.

  In a tenth technical means, in any one of the first to seventh technical means, an image source generated by a specific application operating in a digital broadcast receiver can be output as a plurality of types of image sources. The switching from the output of the image source generated to the digital broadcast signal is the switching of the selection of the output target.

  According to an eleventh technical means, in any one of the third to sixth technical means, when the output target is switched to the digital broadcast signal, the stream including the key frame stored in the buffer is decoded and output. In the meantime, the output of any of a plurality of types of image sources is continued so that the output is not interrupted.

  The twelfth technical means includes means for delaying the output of the multi-segment broadcast signal by a predetermined time in the eighth technical means, and a multi-segment broadcast signal that causes a time difference until the output when the same program is being broadcast. It is characterized by eliminating the time difference in output from the one-segment broadcast signal.

  According to the present invention, in a digital broadcast receiver capable of selecting and outputting a specific content from a plurality of contents including a digital broadcast signal, while obtaining a power saving effect without outputting the digital broadcast signal, When switching to the digital broadcast signal, the digital broadcast signal can be output promptly without a sense of incongruity.

It is a figure which shows an example of the electronic device which can apply the digital broadcast receiver by this invention, and is a figure which shows the external appearance structure of a mobile telephone. It is a block diagram which shows the structural example of the digital broadcast receiver by this invention. FIG. 3 is a block diagram illustrating a detailed configuration example of a full segment decoder, a one segment decoder, and a video switching unit of the digital broadcast receiver illustrated in FIG. 2. It is a figure for demonstrating operation | movement of the 1st Example of the digital broadcast receiver by this invention. It is a flowchart for demonstrating the flow of a process in the 1st Example of the digital broadcast receiver by this invention. It is a figure which shows the example of the control timing of the decoder part in the 1st Example of the digital broadcast receiver by this invention. It is a figure for demonstrating operation | movement of the 2nd Example of the digital broadcast receiver by this invention. It is a flowchart for demonstrating the flow of a process in the 2nd Example of the digital broadcast receiver by this invention. It is a figure which shows the example of the control timing of the decoder part in the 2nd Example of the digital broadcast receiver by this invention. It is a figure for demonstrating operation | movement of the 3rd Example of the digital broadcast receiver by this invention. It is a flowchart for demonstrating the flow of a process in the 3rd Example of the digital broadcast receiver by this invention. It is a figure which shows the example of the control timing of the decoder part in the 3rd Example of the digital broadcast receiver by this invention. It is a figure for demonstrating operation | movement of the 4th Example of the digital broadcast receiver by this invention. It is a flowchart for demonstrating the flow of a process in the 4th Example of the digital broadcast receiver by this invention. It is a flowchart for demonstrating the flow of a process in the 4th Example of the digital broadcast receiver by this invention, and is a figure following FIG. It is a figure which shows the example of the control timing of the decoder part in the 4th Example of the digital broadcast receiver by this invention. It is a figure for demonstrating operation | movement of the 5th Example of the digital broadcast receiver by this invention. It is a flowchart for demonstrating the flow of a process in the 5th Example of the digital broadcast receiver by this invention. It is a flowchart for demonstrating the flow of a process in the 5th Example of the digital broadcast receiver by this invention, and is a figure following FIG. It is a figure which shows the example of the control timing of the decoder part in the 5th Example of the digital broadcast receiver by this invention. It is a figure for demonstrating operation | movement of the 6th Example of the digital broadcast receiver by this invention. It is a flowchart for demonstrating the flow of a process in the 6th Example of the digital broadcast receiver by this invention. It is a figure which shows the example of the control timing of the decoder part in the 6th Example of the digital broadcast receiver by this invention. In the digital broadcast receiver according to the present invention, the H.264 3 is a flowchart for explaining an example of processing when detecting the head of an IDR picture based on H.264 / AVC. It is a figure explaining the outline | summary of terrestrial digital broadcasting.

  FIG. 1 is a diagram showing an example of an electronic device to which a digital broadcast receiver according to the present invention can be applied, and is a diagram showing an external configuration of a mobile phone. The mobile phone 100 has a display unit 101 and a key input unit 102. The digital broadcast receiver according to the present invention can be applied to the mobile phone 100. For example, the mobile phone 100 can be configured to receive both one-segment broadcasting and full-segment broadcasting, and any broadcasting service can be viewed according to the user's selection. Also, when the reception quality of full-segment broadcasting deteriorates during viewing of full-segment broadcasting, it is possible to switch to one-segment broadcasting and output, and to return to full-segment broadcasting output according to the improvement in reception quality of full-segment broadcasting it can. These digital broadcast signals correspond to image sources that can be output by the digital broadcast receiver according to the embodiment of the present invention.

In addition, the mobile phone 100 can operate by installing applications such as e-mail and Internet browser, and an image generated by these applications is displayed on the display unit 101 in response to a user operation. This image may be text or image information by e-mail or site information displayed on a browser, for example. That is, an image generated by an application also corresponds to an image source that can be output by the digital broadcast receiver according to the embodiment of the present invention.
The cellular phone 100 has a function of selecting and outputting one image source from these image sources.

  The digital broadcast receiver according to the present invention is not limited to a portable terminal such as the mobile phone 100 described above, and can be applied to various devices and terminal devices having a digital broadcast receiving function.

  FIG. 2 is a block diagram showing a configuration example of a digital broadcast receiver according to the present invention. The digital broadcast receiver 1 includes a full segment tuner 11 that is a tuner unit that selects a full segment broadcast received by an antenna 10 and a one segment tuner 12 that selects a one segment broadcast.

  The full segment (12 segment) TS output from the full segment tuner 11 is input to the full segment full-segment OFDM demodulator 13 and demodulated. The demodulated TS is input to the full-segment TS decoder 15, and an audio (Audio) signal and a video (Video) signal are separated and output as an ES (Elementary Stream). The audio signal output from the full segment TS decoder 15 is decoded by an audio decoder (not shown), and is output as audio by an audio output unit such as a speaker (not shown).

  Further, the video signal output from the full segment TS decoder 15 is input to the full segment decoder 17 and subjected to decoding processing. An example of a more detailed configuration and operation of the full segment decoder 17 will be described later. The video signal output from the full segment decoder 17 is output to the display unit 20 via the video switching unit 19 and displayed.

  On the other hand, the one-segment broadcasting TS selected by the one-segment tuner 12 is input to the one-segment one-segment OFDM demodulator 14 and demodulated. Then, the demodulated TS is input to the one-segment TS decoder 16, and an audio (Audio) signal and a video (Video) signal are separated and output as ES. The audio signal output from the one-segment TS decoder 16 is decoded by an audio decoder (not shown) and output as audio by an audio output unit such as a speaker (not shown).

  In addition, the video signal output from the one-segment TS decoder 16 is input to the one-segment decoder 18 to be decoded. An example of a more detailed configuration and operation of the one-segment decoder 18 will be described later. The video signal output from the one-segment decoder 18 is output to the display unit 20 via the video switching unit 19 and displayed.

  The control unit 21 controls each unit of the digital broadcast receiver 1. The operation input unit 22 receives an operation input by the user, and corresponds to the key input unit 102 in the mobile phone of FIG. In addition, operation input means such as a touch panel and a remote control can also be applied.

The full-segment OFDM demodulator 13 monitors the reception quality of the full-segment broadcast selected by the full-segment tuner 11, and determines that the reception quality of the full-segment broadcast has deteriorated. Switch to the output display of 1Seg broadcasting. At this time, an audio signal (not shown) is also switched from a full-segment broadcast audio signal to a one-segment broadcast audio signal. The determination of deterioration of the reception state is performed according to a predetermined condition. For example, the full-segment OFDM demodulator 13 determines whether or not the reception state has deteriorated by comparing a predetermined characteristic value of a CN or an error rate (BER; Bit Error Rate) detected by the full-segment tuner 11 with a predetermined threshold value. To do. In addition, switching between full-segment broadcasting and one-segment broadcasting can also be executed in accordance with a predetermined operation input to the operation input unit 22.
The present invention can be realized as a chip. In that case, the range of the full segment TS decoder 15, the one segment TS decoder 16, the full segment decoder 17, and the one segment decoder 18 may be built in one chip. Alternatively, the range of the full segment tuner 11, the one segment tuner 12, the full segment OFDM demodulator 13, the one segment OFDM demodulator 14, the full segment TS decoder 15, the one segment TS decoder 16, the full segment decoder 17, and the one segment decoder 18 may be built in one chip. .

FIG. 3 is a block diagram illustrating a detailed configuration example of the full segment decoder, the one segment decoder, and the video switching unit of the digital broadcast receiver illustrated in FIG.
An MPEG-2 stream (encoded data) of full segment broadcasting is input to the full segment decoder 17. The encoded data of full segment broadcasting input to the full segment decoder 17 is decoded by a variable length decoding unit (VLD) 171.

  In the full segment decoder 17, the quantization coefficient obtained by decoding is inversely quantized by an inverse quantization unit (IQ) 172, and the inversely quantized transform coefficient is inversely DCT transformed by an inverse DCT unit (IDCT) 173. The residual image reconstructed by the inverse DCT transform is added to the prediction block output from the motion compensation unit (MC) 175 by the adding unit 174 and output to the video switching unit 19. The reconstructed residual image output from the adder 175 is stored in the frame memory 176, a prediction block is generated by the motion compensator (MC) 175, and is output to the adder 174. The motion compensation unit 175 calculates a motion vector from the difference vector decoded by the variable length decoding unit 171 and uses it to generate a prediction block.

  On the other hand, the one-seg decoder 18 includes one-segment broadcasting H.264. An H.264 / AVC stream (encoded data) is input. The IDR picture is detected by the pattern detection unit 181 from the encoded data of the one segment broadcast input to the one-segment decoder 18 and is decoded by the variable length decoding unit (VLD) 182. The pattern detection unit 181 corresponds to a key frame detection unit that detects a key frame in the present invention.

  The quantization coefficient obtained by the variable length decoding unit 182 is inversely quantized by the inverse quantization unit (IQ) 183, and the inversely quantized transform coefficient is inversely DCT transformed by the inverse DCT unit (IDCT) 184. The residual image reconstructed by inverse DCT is added to the prediction block output from the motion compensation unit 188 by the addition unit 185, and blocking artifacts are reduced by the deblocking filter 186 and output to the video switching unit 19. . The reconstructed residual image output from the deblocking filter 186 is stored in the frame memory 187, a prediction block is generated by the motion compensation unit (MC) 188, and is output to the addition unit 185. The motion compensation unit 188 calculates a motion vector from the difference vector decoded by the variable length decoding unit 182 and uses it to generate a prediction block.

  The buffer 189 stores the IDR picture detected by the pattern detection unit 181 as encoded data. In an embodiment according to the present invention, which will be described later, when outputting full-segment broadcasting, the IDR picture detected by the pattern detection unit 181 is stored in the buffer 189, or the stream from the detected IDR picture to the next IDR picture is stored, When the full-segment broadcast output is switched from the full-segment broadcast output to the one-segment broadcast output in accordance with the degradation of the reception quality of the full-segment broadcast, the encoded data read from the buffer 189 is decoded and output. In another embodiment, without decoding the buffer 189, the one-segment broadcast IDR picture is stored in the frame memory 187 when the full-segment broadcast is output, and is decoded when the full-segment broadcast is switched to the one-segment broadcast. Video output is performed using the completed data. Accordingly, it is possible to provide a digital broadcast receiver that can quickly output video without a sense of incompatibility when switching from full-segment broadcasting to one-segment broadcasting. Details of the operation of each embodiment will be described below.

(First embodiment)
FIG. 4 is a diagram for explaining the operation of the first embodiment of the digital broadcast receiver according to the present invention. Here, an example of processing when switching to one-segment broadcasting while full-segment broadcasting is being displayed by the digital broadcasting receiver and processing when returning from the switched one-segment broadcasting to full-segment broadcasting will be described.

  As described above, in a digital broadcast receiver capable of receiving both one-segment broadcasting and full-segment broadcasting, if the reception state deteriorates when receiving and outputting full-segment broadcasting, the one-segment broadcasting broadcasted by simul There is something to switch. In this case, full-seg broadcasting has higher image quality and higher sound quality than one-seg broadcasting, requires a high CN (Career to Noise), and uses 64QAM as a modulation method, so that errors during transmission are likely to occur. . Therefore, when the reception state of the full segment broadcast is deteriorated due to the reception environment or the like during the output of the full segment broadcast, the output is switched to the one segment broadcast with low image quality and low sound quality but low required CN and less error. By switching from full-segment broadcasting to one-segment broadcasting according to such a reception state, it is possible to continue the output of the received broadcasting service without interruption even if there is some degradation in quality.

It is also possible to manually switch between full-segment broadcasting and one-segment broadcasting. In this case, when the user performs a predetermined operation on the operation input unit 22 of the digital broadcast receiver 1, switching from full segment broadcasting to one segment broadcasting and switching from one segment broadcasting to full segment broadcasting are appropriately performed. Can do.
In the following embodiment, an explanation will be given using the operation of switching between full-segment broadcasting and one-segment broadcasting according to the reception state of full-segment broadcasting, but the same processing can be applied to switching operations by user operations. The same applies to other embodiments of the present invention described below.

  In the digital broadcast receiver for switching between full-segment broadcasting and one-segment broadcasting, in the first embodiment according to the present invention, when full-segment broadcasting is decoded and output, a key frame is generated from encoded data of one-segment broadcasting. By detecting a certain IDR picture and storing the stream from the detected IDR picture to the next IDR picture in the buffer 189, the power consumption can be reduced, and the switching display from full segment broadcasting to one segment broadcasting is uncomfortable. So that you can do it quickly.

  For example, it is assumed that full segment broadcasting is decoded and output in the state A of FIG. In this state A, in the one-seg broadcasting processing system, the pattern detection unit 181 detects an IDR picture that is a key frame from the stream input to the one-seg decoder 18. Here, the pattern detection unit 181 performs processing for detecting an IDR picture by pattern matching.

  In the one-segment decoder 18, the stream after the IDR picture detected by the pattern detection unit 181 is stored in the buffer 189. When the pattern detection unit 181 detects the next IDR picture, the stream from the previous IDR picture saved up to now to the picture immediately before the current IDR picture is deleted from the buffer 189 and discarded. The stream after the current IDR picture is stored in the buffer 189. While the full-segment broadcasting is decoded and output in this way, the process of saving the stream between the IDR pictures of this one-segment broadcasting (from the IDR picture to immediately before the next IDR picture) is repeatedly executed.

  Next, when the digital broadcast receiver 1 is switched to the output of the one-segment broadcasting due to the deterioration of the reception quality of the full-segment broadcasting in the state A, the digital broadcasting receiver 1 shifts to the state B. When the reception quality of the full segment broadcast is deteriorated, the full segment broadcast cannot be decoded. When the full-segment broadcasting is switched to the one-segment broadcasting, the one-seg decoder 18 decodes the stream stored in the buffer 189 from the first IDR picture and causes the display unit 20 to output the stream. The IDR picture can be decoded independently, and decoding of the subsequent continuous stream is possible by decoding the IDR picture.

  That is, in the state B, after the switching, the stream after the IDR picture stored in the buffer 189 is decoded and displayed. Here, it is not necessary to search for an IDR picture from the one-segment broadcasting at the time of switching, and the decoding of the stream stored in the buffer 189 can be started immediately. Note that when switching from full-segment broadcasting to one-segment broadcasting, the full-segment broadcasting is displayed until the decoded one-segment broadcasting is displayed so that the video is not interrupted in a very short time for decoding the stream stored in the buffer 189. It is advisable to display the broadcast screen.

  After the stream stored in the one-segment buffer 189 is displayed, the received one-segment broadcast is continuously displayed. In this case, the stream is received while sequentially storing the received one-segment broadcast stream in the buffer 189. The stream is read from the buffer 189 by FIFO (First In First Out) so as to be continuous in time and decoded. Alternatively, after decoding and outputting the stream in the buffer 189, switching to the one-segment broadcasting being received may be performed. In this case, there is not a sense of incongruity in appearance, and there is no problem that the video is interrupted and the visual quality is low.

  When the one-segment broadcasting is being output (state B) and the reception state of the full-segment broadcasting is improved again to switch to the full-segment broadcasting, the state transitions to the state C. In the state C, the full-segment broadcasting stream is decoded, and when the output becomes possible, the one-segment broadcasting is switched to the full-segment broadcasting. Full-segment broadcasting can be displayed by decoding from an I picture that is a key frame of an MPEG-2 stream. In the state C where the full segment broadcast is being output, the process of detecting the IDR picture from the one-segment broadcast stream and storing the stream up to the next IDR picture in the buffer 189 is repeated as in the state A.

  According to the processing of this embodiment, the processing system of the one-segment broadcasting that is operating when outputting the full-segment broadcasting is only the pattern detection unit 181 and the buffer 189, which consumes less power than the normal decoding processing of the one-segment broadcasting. Can be reduced. Further, according to the present embodiment, it is necessary to add a buffer 189 to the normal one-segment decoder 18, but for example, the required memory capacity is 416 kbps which is the bit rate of one-segment broadcasting and the maximum interval between IDR pictures. Considering 5 seconds as an example, a small scale of about 300 kBytes is sufficient.

  Audio output is also switched in synchronization with the video when switching from full segment broadcasting to one segment broadcasting. In this embodiment, when switching from full-segment broadcasting to one-segment broadcasting, the continuity of the sound is slightly interrupted, but before switching, the audio output of full-segment broadcasting is faded out, and the sound of the one-segment broadcasting after switching is faded in. Thus, the uncomfortable feeling at the time of switching may be further alleviated. In addition, at the time of switching from full segment broadcasting to one segment broadcasting, for example, the sound may be silenced for about several milliseconds. In this case, a method of muting the audio output before switching, muting the audio output after switching, or muting both audio outputs can be considered. Also in the other embodiments described below, the same operation can be performed for the audio output switching process, and repeated description will be omitted.

FIG. 5 is a flowchart for explaining the processing flow in the first embodiment of the digital broadcast receiver according to the present invention.
The digital broadcast receiver 1 monitors the reception quality while receiving full-segment broadcasting. If the reception quality of the full-segment broadcasting has not deteriorated, the encoded stream data is input to the pattern detection unit 181 of the one-segment decoder 18 (step S2), and the pattern detection unit 181 detects the head of the IDR picture. (Step S3). If the head of the IDR picture is not detected, data input to the pattern detection unit 181 is continued. If the head of the IDR picture is detected (Yes in step S3), the one-segment decoder 18 includes the contents of the pattern detection unit 181. Is stored in the buffer 189 (step S4). The content of the pattern detection unit 181 is stream data input after the detected IDR picture.

  If the reception quality of full-segment broadcasting has not deteriorated in this state (step S5-No), one-segment broadcasting stream data is input to the pattern detection unit 181 (step S6). When the head of the IDR picture is detected (step S7-Yes), the buffer 189 is cleared (step S8), and the contents of the pattern detection unit 181 are stored in the buffer (step S4).

On the other hand, if the reception quality of full-segment broadcasting deteriorates in step S1 or step S5, it is confirmed that the reception quality of full-segment broadcasting has not recovered (step S9-No), and the buffer 189 of the one-segment decoder 18 is checked. The stream data is read (step S10). If the reception quality of the full segment is recovered, the process returns to step S1.
In the one-segment decoder 18, after the stream data is read out in step S10, the variable length decoding unit 182 performs variable length decoding (step S11), the inverse quantization unit 183 performs inverse quantization (step S12), and the inverse DCT The conversion unit 184 performs inverse DCT conversion (step S13). Next, if it is inter-frame prediction (step S14-Yes), motion compensation processing is performed (step S15), and deblocking filter processing is performed (step S16). If it is not inter-frame prediction (No at Step S14), the deblocking filter process is performed as it is (Step S16). And the image which performed the deblocking filter process is displayed on the display part 20 (step S17).

  FIG. 6 is a diagram showing an example of the control timing of the decoder unit in the first embodiment of the digital broadcast receiver according to the present invention. First, when a full segment broadcast stream is decoded and output under the control of the tuner (state A), the full segment decoder 17 is operating. In the one-segment broadcasting processing system, the pattern detection unit 181 and the buffer 189 operate, and other parts, that is, a variable length decoding unit (VLD) 182, an inverse quantization unit (IQ) 183, and an inverse DCT conversion unit (IDCT). The deblocking filter (DF) 186, the motion compensation unit (MC) 188, and the frame memory 187 are not operating.

  When the reception state of the full segment broadcast deteriorates and the output is switched from the full segment broadcast to the one segment broadcast (state B), the operation of the full segment decoder 17 is stopped. In the state B, in the processing system of the one-segment broadcasting, the pattern detection unit 181 and the buffer 189 remain operating, and other parts, that is, a variable length decoding unit 182, an inverse quantization unit 183, an inverse DCT conversion unit 184, and a decoding unit. The blocking filter 186, the motion compensation unit 188, and the frame memory 187 also operate, and the one-segment broadcasting is decoded and output.

  When the reception status of the full segment broadcast is good again and the one segment broadcast returns to the full segment broadcast (state C), the full segment decoder 17 operates in the same manner as in the state A, and the one segment pattern detection unit 181 and the buffer 189 operate. Will remain. Then, the operations of the other parts, that is, the one-segment variable length decoding unit 182, the inverse quantization unit 183, the inverse DCT conversion unit 184, the deblocking filter 186, the motion compensation unit 188, and the frame memory 187 are stopped, and the full segment broadcasting is performed. Decoded and output.

(Second embodiment)
FIG. 7 is a diagram for explaining the operation of the second embodiment of the digital broadcast receiver according to the present invention. In a digital broadcast receiver that switches between full-segment broadcasting and one-segment broadcasting, the second embodiment according to the present invention detects an IDR picture from a one-segment broadcasting stream when the full-segment broadcasting is decoded and output. By decoding only the detected IDR picture and storing it in the frame memory, the power consumption can be reduced, and the display at the time of switching from full segment broadcasting to one segment broadcasting can be quickly performed without a sense of incongruity. ing.

  For example, it is assumed that full segment broadcasting is decoded and output in the state A of FIG. In this state A, in the one-seg broadcast processing system, the IDR picture is detected by the pattern detection unit 181 from the stream input to the one-seg decoder 18. Here, the pattern detection unit 181 performs processing for detecting an IDR picture by pattern matching.

  The one-segment decoder 18 decodes and stores the IDR picture detected by the pattern detection unit 181. The frame memory 187 can be used as the storage destination of the decoded IDR picture, but other memories may be prepared. In this embodiment, since the decoded IDR picture is stored, the buffer 189 configured as shown in FIG. 3 is not necessary. Therefore, the processing of this embodiment can be executed using the configuration of a conventional ordinary one-segment decoder.

  When the pattern detection unit 181 detects the next IDR picture, the decoded image of the previous IDR picture stored so far is deleted from the frame memory 187 and discarded, and the current IDR picture is decoded and the frame Save in memory 187. While the full-segment broadcasting is decoded and output in this way, the decoded image saving process for each IDR picture of the one-segment broadcasting is repeatedly executed.

  Next, when the digital broadcast receiver switches to the output of the one-segment broadcasting due to the deterioration of the reception quality of the full-segment broadcasting in the state A, the digital broadcasting receiver shifts to the state B. When the reception quality of the full segment broadcast is deteriorated, the full segment broadcast cannot be decoded. When the full-segment broadcasting is switched to the one-segment broadcasting, the one-seg decoder 18 outputs the decoded image stored in the frame memory 187. That is, in the state B, the decoded image of the IDR picture stored in the frame memory 187 from the beginning of the switching is displayed. Then, the display of the output IDR picture is maintained as it is, and the improvement of the reception state of full segment broadcasting is awaited. When the IDR picture next to the IDR picture being output is received, the IDR picture is decoded and switched from the currently displayed IDR picture. As a result, a decoded image is displayed for each IDR picture. Such display eliminates the need to search for the IDR picture of the one-segment broadcast when switching from the full-segment broadcast to the one-segment broadcast, and the decoded image stored in the frame memory 187 can be displayed immediately.

  When switching from the state of outputting the IDR picture of the one-segment broadcasting (state B) to the output of the full-segment broadcasting again due to the improved reception state, the state transitions to the state C. In state C, the full-segment broadcasting stream is decoded, and when the output becomes possible, the one-segment broadcasting is switched to the full-segment broadcasting. Full segment broadcasting can be decoded from the I picture of the stream and displayed. In the state C in which the full segment broadcast is output, the process of detecting the IDR picture from the one-segment broadcast stream, decoding the detected IDR picture, and storing it in the frame memory 187 is repeated as in the state A.

  According to the processing of this embodiment, at the time of output of full segment broadcasting, in the processing system of one segment broadcasting, only the processing of detecting the IDR picture by the pattern detection unit 181 and decoding only the IDR picture and storing it in the frame memory 187. Since it is performed, power consumption can be reduced as compared with a normal decoding process of one-segment broadcasting. Further, according to the present embodiment, since the IDR picture is decoded and stored in the frame memory 187 of the one-segment decoder 18, switching display can be instantaneously performed when switching from full-segment broadcasting to one-segment broadcasting. In addition, the control of these processing systems is simple.

FIG. 8 is a flowchart for explaining the flow of processing in the second embodiment of the digital broadcast receiver according to the present invention.
The digital broadcast receiver 1 monitors the reception quality while receiving full-segment broadcasting. If the reception quality of full-segment broadcasting has not deteriorated (step S21-No), the encoded stream data is input to the pattern detection unit 181 of the one-seg decoder 18 (step S22), and the pattern detection unit 181 performs IDR. The head of the picture is detected (step S23).

  If the head of the IDR picture is not detected, data input to the pattern detection unit 181 is continued. When the head of the IDR picture is detected (step S23-Yes), the variable length decoding unit 182 performs variable length decoding (step S24), and the inverse quantization unit 183 performs inverse quantization (step S25). ), The inverse DCT transform unit 184 performs inverse DCT transform (step S26). Then, a deblocking filter process is performed (step S27), and the decoded image is stored in the frame memory 187 (step S28). Thereafter, it is determined whether or not the decoding of one frame of the IDR picture has been completed (step S29). If the decoding of one frame has not been completed, the process returns to step S24 to perform the decoding process, and the decoding of one frame has been completed. If so, the process returns to step S21 to determine the reception quality of full segment broadcasting.

  If the reception quality of the full segment broadcast deteriorates in step S21, it is confirmed that the reception quality of the full segment broadcast has not recovered (step S30-No), and data is read from the frame memory 187 of the one-segment decoder 18 (step S31). Is displayed on the display unit 20 (step S32). If the reception quality of full-segment broadcasting is recovered in step S30, the process returns to step S21.

  If the reception quality of full-seg broadcasting has not been recovered after displaying a one-segment broadcasting image in step S32 (step S33-No), the encoded stream data is input to the pattern detection unit 181 of the one-seg decoder. Then, the head of the IDR picture is detected by the pattern detection unit 181 (step S35).

  If the head of the IDR picture is not detected, data input to the pattern detection unit 181 is continued. When the head of the IDR picture is detected (step S35-Yes), the variable length decoding unit 182 performs variable length decoding (step S36), and the inverse quantization unit 183 performs inverse quantization (step S37). ), The inverse DCT transform unit 184 performs inverse DCT transform (step S38). Then, a deblocking filter process is performed (step S39) and displayed on the display unit (step S40). Then, it is determined whether or not the decoding of one frame of the IDR picture has been completed (step S41). If the decoding of one frame has not been completed, the process returns to step S36 to perform the decoding process, and the decoding of one frame has been completed. If so, the process returns to step S33 to determine the reception quality of full segment broadcasting.

  FIG. 9 is a diagram showing an example of control timing of the decoder unit in the second embodiment of the digital broadcast receiver according to the present invention. First, when a full-segment broadcast stream is decoded and output under the control of the tuner (state A), the full-segment decoder 17 is operating. In the one-seg broadcasting processing system, the pattern detection unit 181 operates, and further, at the timing when the IDR picture is detected, the variable length decoding unit (VLD) 182, the inverse quantization unit (IQ) 183, and the inverse DCT conversion unit (IDCT). 184, the deblocking filter (DF) 186, and the frame memory 187 operate. Since decoding is performed for each IDR picture, the motion compensation unit (MC) 188 does not operate.

  When the reception state of the full segment broadcast deteriorates and the output is switched from the full segment broadcast to the one segment broadcast (state B), the operation of the full segment decoder 17 is stopped. Also in state B, the operation of the one-segment processing system is the same as in state A, and the variable length decoding unit 182 and the inverse quantization unit 183 are operated at the timing when the pattern detection unit 181 operates and the IDR picture is detected. The one-segment inverse DCT converter 184, the deblocking filter 186, and the frame memory 187 operate. Thereby, the image of the IDR picture of the one-segment broadcasting is displayed. When the IDR picture next to the displayed IDR picture is received, the image of the IDR picture is switched.

  When the reception state of the full segment broadcast is good again and the one segment broadcast returns to the full segment broadcast (state C), the full segment decoder 17 operates as in the state A. Then, similarly to the states A and B, at the timing when the pattern detection unit 181 operates and the IDR picture is detected, the variable length decoding unit 182, the inverse quantization unit 183, the inverse DCT conversion unit 184, the deblocking filter 186, and The frame memory 187 operates.

(Third embodiment)
FIG. 10 is a diagram for explaining the operation of the third embodiment of the digital broadcast receiver according to the present invention. In a digital broadcast receiver that switches between full-segment broadcasting and one-segment broadcasting, in the third embodiment according to the present invention, when a full-segment broadcasting is decoded and output, an IDR picture is detected from the one-segment broadcasting stream. By decoding only the detected IDR picture and storing it in the frame memory, it is possible to reduce power consumption and to quickly display the display when switching from full segment to one segment. . The difference from the second embodiment is that the stream is displayed by decoding from the IDR picture next to the IDR picture stored in the frame memory when the one-segment broadcasting is output. This will be specifically described below.

  For example, it is assumed that the full segment broadcast is decoded and output in the state A of FIG. In this state A, in the one-seg broadcast processing system, the IDR picture is detected by the pattern detection unit 181 from the stream input to the one-seg decoder 18. Here, the pattern detection unit 181 performs processing for detecting an IDR picture by pattern matching.

  Then, the one-segment decoder 18 decodes and stores the IDR picture detected by the pattern detection unit 181. The frame memory 187 can be used as the storage destination of the decoded IDR picture, but other memories may be prepared. In this embodiment, since the decoded IDR picture is stored, the buffer 189 configured as shown in FIG. 3 is not necessary. Therefore, the processing of this embodiment can be executed using the configuration of a conventional ordinary one-segment decoder.

  When the pattern detection unit 181 detects the next IDR picture, the decoded image of the previous IDR picture stored so far is deleted from the frame memory 187 and discarded, and the current IDR picture is decoded and the frame Save in memory 187. While the full-segment broadcasting is decoded and output in this way, the decoded image saving process for each IDR picture of the one-segment broadcasting is repeatedly executed.

  Next, when the digital broadcast receiver is switched to the output of the one-segment broadcasting due to the deterioration of the reception quality of the full-segment broadcasting or the like in the state A, the digital broadcasting receiver shifts to the state B. When the reception quality of the full segment broadcast is deteriorated, the full segment broadcast cannot be decoded. When the full-segment broadcasting is switched to the one-segment broadcasting, the one-seg decoder 18 outputs the decoded image stored in the frame memory 187. That is, in the state B, the decoded image of the IDR picture stored in the frame memory 187 from the beginning of the switching is displayed. Then, the display of the output IDR picture is maintained as it is. When the IDR picture next to the IDR picture being output is received, the stream subsequent to the IDR picture is decoded and switched to the currently displayed IDR picture. As a result, the display of only the first IDR picture stored in the frame memory 187 is maintained, and the decoded stream image is displayed from the next IDR picture. With such a display, when switching from full-segment broadcasting to one-segment broadcasting, it is not necessary to search for an IDR picture from the one-segment broadcasting, and the decoded image stored in the frame memory 187 can be displayed immediately, and further from the next IDR picture. Can display a decoded one-segment broadcasting image.

  When switching from the state of outputting the IDR picture of the one-segment broadcasting (state B) to the output of the full-segment broadcasting again due to the improved reception state, the state transitions to the state C. In state C, the full-segment broadcasting stream is decoded, and when the output becomes possible, the one-segment broadcasting is switched to the full-segment broadcasting. Full segment broadcasting can be decoded from the I picture of the stream and displayed. In the state C in which the full segment broadcast is output, the process of detecting the IDR picture from the one-segment broadcast stream, decoding the detected IDR picture, and storing it in the frame memory 187 is repeated as in the state A.

According to the processing of this embodiment, at the time of output of full segment broadcasting, in the processing system of one segment broadcasting, only the processing of detecting the IDR picture by the pattern detection unit 181 and decoding only the IDR picture and storing it in the frame memory 187. Since it is performed, power consumption can be reduced as compared with a normal decoding process of one-segment broadcasting.
Further, according to the present embodiment, since the IDR picture is decoded and stored in the frame memory 187 of the one-segment decoder 18, switching display can be instantaneously performed when switching from full-segment broadcasting to one-segment broadcasting. In addition, when switching from full-segment broadcasting to one-segment broadcasting, since the decoded stream image is displayed from the next IDR picture, it is possible to display the one-segment broadcasting with little discomfort.

FIG. 11 is a flowchart for explaining the flow of processing in the third embodiment of the digital broadcast receiver according to the present invention.
The digital broadcast receiver 1 monitors the reception quality while receiving full-segment broadcasting. If the reception quality of full-segment broadcasting has not deteriorated (step S51-No), the encoded stream data is input to the pattern detection unit 181 of the one-seg decoder 18 (step S52), and the pattern detection unit 181 performs IDR. The head of the picture is detected (step S53).

  If the head of the IDR picture is not detected, data input to the pattern detection unit 181 is continued. If the head of the IDR picture is detected (step S53-Yes), variable length decoding is performed by the variable length decoding unit 182 (step S54), and inverse quantization is performed by the inverse quantization unit 183 (step S55). ), The inverse DCT transform unit 184 performs inverse DCT transform (step S56). Then, deblocking filter processing is performed (step S57), and the decoded image is stored in the frame memory 187 (step S58). Thereafter, it is determined whether or not the decoding of one frame of the IDR picture has been completed (step S59). If the decoding of one frame has not been completed, the process returns to step S54 to perform the decoding process, and the decoding of one frame has been completed. If so, the process returns to step S51 to determine the reception quality of full segment broadcasting.

  If the reception quality of the full segment broadcast has deteriorated in step S51, it is confirmed that the reception quality of the full segment broadcast has not recovered (step S60-No), and data is read from the frame memory 187 of the one-segment decoder 18 (step S61). Is displayed on the display unit 20 (step S62). On the other hand, if the reception quality of full-segment broadcasting is recovered in step S60, the process returns to step S51.

  If the reception quality of the full-segment broadcasting is not recovered after displaying the one-segment broadcasting image in step S62 (step S63-No), data is read from the buffer 189 (step S64). Here, the next IDR picture is detected by the pattern detection unit 181 for one-segment broadcasting and stored in the buffer 189. After switching from full segment broadcasting to one segment broadcasting, the decoded IDR picture is read from the frame memory 187 and displayed, and then the next IDR picture is streamed using the encoded IDR picture stored in the buffer 189. To decrypt and display.

  After reading the data from the buffer in the above step S64, the variable length decoding unit 182 performs variable length decoding (step S65), the inverse quantization unit 183 performs inverse quantization (step S66), and the inverse DCT conversion unit 184. Then, inverse DCT transformation is performed (step S67). Next, if it is inter-frame prediction (step S68-Yes), motion compensation processing is performed (step S69), and deblocking filter processing is performed (step S70). If it is not inter-frame prediction (No at Step S68), the deblocking filter process is performed as it is (Step S70). And the image which performed the deblocking filter process is displayed on a display part (step S71), and it returns to step S63 and confirms the reception quality of a full segment. If the reception quality of full segment broadcasting is recovered in step S63, the process returns to step S51.

  FIG. 12 is a diagram showing an example of the control timing of the decoder unit in the third embodiment of the digital broadcast receiver according to the present invention. First, when a full-segment broadcast stream is decoded and output under the control of the tuner (state A), the full-segment decoder 17 is operating. In the one-segment broadcasting processing system, the pattern detection unit 181 and the buffer 189 are operating. Furthermore, in the processing system of one-segment broadcasting, at the timing when an IDR picture is detected, a variable length decoding unit (VLD) 182, an inverse quantization unit (IQ) 183, an inverse DCT transform unit (IDCT) 184, a deblocking filter (DF ) 186 and the one-segment frame memory 187 operate. Since decoding is performed for each IDR picture, the one-segment motion compensation unit (MC) 188 does not operate.

  When the reception state of the full segment broadcast deteriorates and the output is switched from the full segment broadcast to the one segment broadcast (state B), the operation of the full segment decoder 17 is stopped. Also in the state B, the operations of the pattern detection unit 181 and the buffer 189 in the one-seg broadcast processing system are maintained. In addition, the variable length decoding unit 182, the inverse quantization unit 183, the inverse DCT conversion unit 184, the deblocking filter 186, and the frame memory 187 of the one-segment broadcasting processing system are decoded and stored in the frame memory 187. An operation for decoding a stream from the IDR picture next to the picture is performed. Thus, when switching from full segment broadcasting to one segment broadcasting, the decoded IDR picture stored in the frame memory 187 is first displayed, and the stream is displayed while decoding from the next IDR picture. Switching display is performed with little uncomfortable feeling.

  When the reception status of the full-segment broadcast becomes good again and the one-segment broadcast returns to the full-segment broadcast (state C), as in the state A, the full-segment decoder 17, the pattern detection unit 181 of the one-segment broadcast processing system, and the one-segment broadcast buffer In addition, the variable length decoding unit 182, the inverse quantization unit 183, the inverse DCT transform unit 184, the deblocking filter 186, and the frame memory 187 are operated at the timing when the IDR picture is detected. Here, the one-segment motion compensation unit 188 does not operate.

(Fourth embodiment)
FIG. 13 is a diagram for explaining the operation of the fourth embodiment of the digital broadcast receiver according to the present invention. In a digital broadcast receiver that switches between full-segment broadcasting and one-segment broadcasting, in the fourth embodiment according to the present invention, when decoding and outputting full-segment broadcasting, an IDR picture is obtained from encoded data of one-segment broadcasting. A stream from the detected IDR picture to the next IDR picture is stored in a buffer. When switching from full-segment broadcasting to one-segment broadcasting, the full-segment broadcasting still image is displayed until decoding of the one-segment broadcasting is possible, and the one-segment broadcasting processing system performs fast-forward playback from the IDR picture stored in the buffer, When the stored data in the buffer becomes empty, switching from full-segment broadcasting still image to normal decoding display of one-segment broadcasting reduces power consumption and prompts the display when switching from full-segment to one-segment broadcasting without a sense of incongruity To be able to do that.

  For example, assume that full-segment broadcasting is decoded and output in the state A of FIG. In this state A, in the one-seg broadcasting processing system, the pattern detection unit 181 detects an IDR picture from the encoded stream input to the one-seg decoder 18. Here, the pattern detection unit 181 performs processing for detecting an IDR picture by pattern matching.

  In the one-segment decoder 18, the stream after the IDR picture detected by the pattern detection unit 181 is stored in the buffer 189. When the pattern detection unit 181 detects the next IDR picture, the stream from the previous IDR picture stored until now to the picture immediately before the current IDR picture is deleted from the buffer 189 and discarded. The stream after the IDR picture is stored in the buffer 189. While the full-segment broadcasting is decoded and output in this manner, the stream storing process for each IDR picture of the one-segment broadcasting is repeatedly executed. As described above, in the state A in which full-segment broadcasting is output, the present embodiment operates in the same manner as the first embodiment described above.

  Next, when the digital broadcast receiver is switched to the output of the one-segment broadcasting due to the deterioration of the reception quality of the full-segment broadcasting or the like in the state A, the digital broadcasting receiver shifts to the state B. When the reception quality of the full segment broadcast is deteriorated, the full segment broadcast cannot be decoded. When the full-segment broadcasting is switched to the one-segment broadcasting, the one-seg decoder 18 decodes the stream stored in the buffer 189 from the first IDR picture and causes the display unit 20 to output the stream. At this time, the decoded stream is displayed with fast-forwarding while dropping frames, and fast-forwarding is continued until the buffer 189 becomes empty. In frame dropping, for example, a process of deleting and outputting two frames out of three is performed. When the buffer 189 is emptied, normal one-segment broadcasting decoding processing is performed for output display.

  In other words, in the state B, the stream after the IDR picture stored in the buffer 189 from the beginning of the switching is decoded, and fast-forwarded and displayed while dropping frames until the buffer 189 becomes empty. Here, it is not necessary to search for an IDR picture from the one-segment broadcasting at the time of switching, and the decoding of the stream stored in the buffer 189 can be started immediately.

  When switching from the state where the one-segment broadcasting is being output (state B) to the output of the full-segment broadcasting again due to the improvement of the reception state, the state transitions to the state C. In state C, the full-segment broadcasting stream is decoded, and when the output becomes possible, the one-segment broadcasting is switched to the full-segment broadcasting. Full segment broadcasting can be decoded from the I picture of the stream and displayed. In the state C where the full segment broadcast is being output, the process of detecting the IDR picture from the one-segment broadcast stream and storing the stream up to the next IDR picture in the buffer 189 is repeated as in the state A.

  According to the processing of this embodiment, when full-segment broadcasting is output, in the processing system of one-segment broadcasting, only the processing of detecting the IDR picture by the pattern detection unit 181 and storing it in the buffer 189 is executed. The power consumption can be reduced compared with the decoding process.

14 and 15 are flowcharts for explaining the flow of processing in the fourth embodiment of the digital broadcast receiver according to the present invention.
The digital broadcast receiver 1 monitors the reception quality while receiving full-segment broadcasting. If the reception quality of full-segment broadcasting has not deteriorated (step S81-No), the encoded stream data is input to the pattern detection unit 181 of the one-seg decoder 18 (step S82), and the pattern detection unit 181 performs IDR. The beginning of the picture is detected (step S83). If the head of the IDR picture is not detected, data input to the pattern detection unit 181 is continued. If the head of the IDR picture is detected (step S83-Yes), the one-segment decoder 18 uses the contents of the pattern detection unit 181. Is stored in the buffer 189 (step S84). The content of the pattern detection unit 181 is stream data input after the detected IDR picture.

  If the reception quality of the full segment broadcast is not deteriorated in this state (No in step S85), the data of the one-segment broadcast stream is input to the pattern detection unit 181 (step S86). When the head of the IDR picture is detected (step S87-Yes), the buffer 189 is cleared (step S88), and the contents of the pattern detection unit 181 are stored in the buffer (step S84).

On the other hand, if the reception quality of the full segment broadcast has deteriorated in step S81 or step S85, it is confirmed that the reception quality of the full segment broadcast has not been recovered (step S89-No), and the buffer 189 of the one segment decoder 18 is checked. The stream data is read (step S90). If the reception quality of full-segment broadcasting has been recovered, the process returns to step S81.
The one-segment decoder 18 determines whether or not the buffer 189 is empty after reading the stream data in step S90 (step S91). If the buffer is not empty, the variable-length decoder 182 performs variable-length decoding. (Step S92), the inverse quantization unit 183 performs inverse quantization (step S93), and the inverse DCT transform unit 184 performs inverse DCT transform (step S94). Next, if it is inter-frame prediction (step S95-Yes), motion compensation processing is performed (step S96), and deblocking filter processing is performed (step S97). If it is not inter-frame prediction (No at Step S95), the deblocking filter process is performed as it is (Step S97).

  And it is discriminate | determined whether the image which performed the deblocking filter process is an image which drops a frame (step S98). Here, in order to fast-forward and display the data read from the buffer 189, a process of displaying by frame dropping is performed. For example, it can be determined that two frames out of three frames are dropped. In step S98, it is determined whether or not the image subjected to the deblocking filter process is image data for dropping frames. If the image data is not subjected to frame dropping, it is displayed on the display unit 20, and the process returns to step S89. On the other hand, if the image data is to drop frames, the process returns to step S89 without displaying on the display unit 20. In this way, while reading out the data stored in the buffer 189, a predetermined frame drop is performed and fast-forward display is performed.

If the buffer 189 is emptied in step S91 described above, the routine proceeds to normal decoding display for one-segment broadcasting. That is, first, it is confirmed that the reception quality of full segment broadcasting has not recovered (step S100-No), data is input to the one segment decoder 18 (step S101), and variable length decoding is performed by the variable length decoding unit 182 of the one segment decoder 18. (Step S102), the inverse quantization unit 183 performs inverse quantization (step S103), and the inverse DCT transform unit 184 performs inverse DCT transform (step S104). Next, if it is inter-frame prediction (step S105-Yes), motion compensation processing is performed (step S106), and deblocking filter processing is performed (step S107). If it is not inter-frame prediction (No at Step S105), the deblocking filter process is performed as it is (Step S107). And the data which performed the deblocking filter process are displayed (step S108).
If the reception quality of full-segment broadcasting has been recovered in step S89 or S100, the process returns to step S81 to start processing for storing the stream between IDR pictures of one-segment broadcasting in the buffer 189.

  FIG. 16 is a diagram showing an example of the control timing of the decoder unit in the fourth embodiment of the digital broadcast receiver according to the present invention. First, when a full-segment broadcast stream is decoded and output under the control of the tuner (state A), the full-segment decoder 17 is operating. In the one-segment broadcasting processing system, the pattern detection unit 181 and the buffer 189 operate, and other parts, that is, a variable length decoding unit (VLD) 181, an inverse quantization unit (IQ) 183, and an inverse DCT conversion unit (IDCT) 184. The deblocking filter (DF) 186, the motion compensation unit (MC) 188, and the frame memory 187 are not operating. Further, the frame advance control signal for displaying the one-segment broadcast stream in the fast-forward state is OFF in the state A. In the case of FIG. 2, the frame advance control signal is a signal generated by the control of the control unit 21, and the one-segment decoder 18 executes a process of dropping two frames out of, for example, three frames according to this control signal and outputting them. To do.

  When the reception state of the full segment broadcast deteriorates and the output is switched from the full segment broadcast to the one segment broadcast (state B), the operation of the full segment decoder 17 is stopped. In the one-seg broadcast processing system, the pattern detection unit 181, variable length decoding unit 182, inverse quantization unit 183, inverse DCT conversion unit 184, deblocking filter 186, motion compensation unit 188, and frame memory 187 operate. The buffer 189 operates until the stream data stored in the state A becomes empty, and then the operation stops. The frame advance control signal is turned ON when switching from full segment broadcasting to one segment broadcasting, and is turned OFF when there is no stream data stored in the buffer 189.

  When the reception state of the full-segment broadcast is improved again and the one-segment broadcast returns to the full-segment broadcast (state C), the full-segment decoder 17 and the pattern detection unit 181 and the buffer 189 of the one-segment broadcast processing system are the same as in the state A. The other parts, that is, the inverse quantization unit 183, the inverse DCT conversion unit 184, the deblocking filter 186, the motion compensation unit 188, and the frame memory 187 in the one-segment broadcasting processing system do not operate. Also, the frame advance control signal remains OFF.

(Fifth embodiment)
FIG. 17 is a diagram for explaining the operation of the fifth embodiment of the digital broadcast receiver according to the present invention. In a digital broadcast receiver that switches between full-segment broadcasting and one-segment broadcasting, in the fifth embodiment according to the present invention, when decoding and outputting full-segment broadcasting, an IDR picture is obtained from encoded data of one-segment broadcasting. A stream from the detected IDR picture to the next IDR picture is stored in a buffer. At the time of reproduction, high-speed decoding is performed from the IDR picture stored in the buffer, but no display is performed, and the screen immediately before the decoding of full-segment broadcasting cannot be performed is displayed as a still image. When the stored data in the buffer becomes empty, switching to the normal decoding display of 1Seg broadcasting will reduce power consumption, and the display when switching from Full Seg to 1Seg will be more continuous and quick without a sense of incongruity To be able to do that.

  For example, assume that full segment broadcasting is decoded and output in state A of FIG. In this state A, in the one-seg broadcasting processing system, the pattern detection unit 181 detects an IDR picture from the encoded stream input to the one-seg decoder 18. Here, the pattern detection unit 181 performs processing for detecting an IDR picture by pattern matching.

  In the one-segment decoder 18, the stream after the IDR picture detected by the pattern detection unit 181 is stored in the buffer 189. When the pattern detection unit 181 detects the next IDR picture, the stream from the previous IDR picture stored until now to the picture immediately before the current IDR picture is deleted from the buffer 189 and discarded. The stream after the IDR picture is stored in the buffer 189. While the full-segment broadcasting is decoded and output in this manner, the stream storing process for each IDR picture of the one-segment broadcasting is repeatedly executed. As described above, in the state A in which full-segment broadcasting is output, the present embodiment operates in the same manner as the first embodiment described above.

  Next, when the digital broadcast receiver is switched to the output of the one-segment broadcasting due to the deterioration of the reception quality of the full-segment broadcasting or the like in the state A, the digital broadcasting receiver shifts to the state B. When the reception quality of the full segment broadcast is deteriorated, the full segment broadcast cannot be decoded. When the full-segment broadcasting is switched to the one-segment broadcasting, the one-segment decoder 18 decodes the stream stored in the buffer 189 from the first IDR picture, but discards it without displaying it. In state B, the screen immediately before the decoding of full-segment broadcasting cannot be performed is displayed as a still image. At the time of switching from state A to state B, the one-segment broadcasting processing system decodes the stream stored in the buffer 189 as fast as possible compared to the normal decoding process, and spends as much time as possible for the buffer 189 to be empty. Shorten. When the buffer 189 is emptied, normal one-segment broadcasting decoding processing is performed to switch from a full-segment broadcasting still image to a one-segment broadcasting decoding stream for output display.

  That is, in the state B, the stream after the IDR picture stored in the buffer 189 from the beginning of the switching is decoded as fast as possible until the buffer 189 becomes empty, but is discarded without being displayed. In the meantime, the screen immediately before the decoding of full-segment broadcasting cannot be displayed as a still image. Here, it is not necessary to search for an IDR picture from the one-segment broadcasting at the time of switching, and the decoding of the stream stored in the buffer 189 can be started immediately.

  When switching from the state where the one-segment broadcasting is being output (state B) to the output of the full-segment broadcasting again due to the improvement of the reception state, the state transitions to the state C. In state C, the full-segment broadcasting stream is decoded, and when the output becomes possible, the one-segment broadcasting is switched to the full-segment broadcasting. Full segment broadcasting can be decoded from the I picture of the stream and displayed. In the state C where the full segment broadcast is being output, the process of detecting the IDR picture from the one-segment broadcast stream and storing the stream up to the next IDR picture in the buffer 189 is repeated as in the state A.

  According to the processing of this embodiment, when full-segment broadcasting is output, in the processing system of one-segment broadcasting, only the processing of detecting the IDR picture by the pattern detection unit 181 and storing it in the buffer 189 is executed. The power consumption can be reduced compared with the decoding process.

18 and 19 are flowcharts for explaining the flow of processing in the fifth embodiment of the digital broadcast receiver according to the present invention.
The digital broadcast receiver 1 monitors the reception quality while receiving full-segment broadcasting. If the reception quality of full-segment broadcasting has not deteriorated (step S111-No), the encoded stream data is input to the pattern detection unit 181 of the one-seg decoder 18 (step S112), and the pattern detection unit 181 performs IDR. The beginning of the picture is detected (step S113). If the head of the IDR picture is not detected, data input to the pattern detection unit 181 is continued. If the head of the IDR picture is detected (Yes in step S113), the one-segment decoder 18 uses the contents of the pattern detection unit 181. Is stored in the buffer 189 (step S114). The content of the pattern detection unit 181 is stream data input after the detected IDR picture.

  If the reception quality of full-segment broadcasting has not deteriorated in this state (No in step S115), the data input of the one-segment broadcasting stream is input to the pattern detection unit 181 (step S116). When the head of the IDR picture is detected (step S117—Yes), the buffer 189 is cleared (step S118), and the contents of the pattern detection unit 181 are stored in the buffer (step S114).

On the other hand, when the reception quality of the full segment broadcasting is deteriorated in the above step S111 or step S115, it is confirmed that the reception quality of the full segment broadcasting is not recovered (step S119-No), and the buffer of the one seg decoder 18 is checked. The stream data is read (step S120). If the reception quality of full-segment broadcasting has been recovered, the process returns to step S111.
The one-segment decoder 18 reads the stream data in step S120, and then performs a process of emptying the buffer 189 as soon as possible by performing a higher-speed decoding than the normal decoding (step S121). Then, it is determined whether or not the buffer 189 is empty (step S122), and if it is not empty, high-speed decoding is continued.

If the buffer 189 is emptied in step S122, the routine proceeds to normal decoding display of one-segment broadcasting. That is, first, it is confirmed that the reception quality of full segment broadcasting has not recovered (step S123-No), data is input to the one segment decoder 18 (step S124), and variable length decoding is performed by the variable length decoding unit 182 of the one segment decoder 18. (Step S125), the inverse quantization unit 183 performs inverse quantization (step S126), and the inverse DCT transform unit 184 performs inverse DCT transform (step S127). Next, if it is inter-frame prediction (step S128-Yes), a motion compensation process is performed (step S129), and a deblocking filter process is performed (step S130). If the prediction is not inter-frame prediction (No in step S128), the deblocking filter process is performed as it is (step S130). And the data which performed the deblocking filter process are displayed (step S131).
If the reception quality of full-segment broadcasting has been recovered in step S119 or S123, the process returns to step S111, and processing for storing the stream between IDR pictures of one-segment broadcasting in the buffer 189 is started.

  FIG. 20 is a diagram showing an example of control timing of the decoder unit in the fifth embodiment of the digital broadcast receiver according to the present invention. First, when a full-segment broadcast stream is decoded and output under the control of the tuner (state A), the full-segment decoder 17 is operating. In the one-segment broadcasting processing system, the pattern detection unit 181 and the buffer 189 operate, and other parts, that is, a variable length decoding unit (VLD) 181, an inverse quantization unit (IQ) 183, and an inverse DCT conversion unit (IDCT) 184. The deblocking filter (DF) 186, the motion compensation unit (MC) 188, and the frame memory 187 are not operating.

When the reception state of the full segment broadcast deteriorates and the output is switched from the full segment broadcast to the one segment broadcast (state B), the operation of the full segment decoder 17 is stopped. At this time, the decoded image immediately before the stop of the full segment decoder 17 is displayed as a still image on the display unit of the digital broadcast receiver.
In the one-seg broadcast processing system, the pattern detection unit 181, variable length decoding unit 182, inverse quantization unit 183, inverse DCT conversion unit 184, deblocking filter 186, motion compensation unit 188, and frame memory 187 operate. The buffer 189 operates until the stream data stored in the state A becomes empty, and then the operation stops. Note that the decoding process in the high-speed decoding period is performed in order to empty the buffer 189 as soon as possible. Depending on the decoding method, the variable-length decoding unit 182, the inverse quantization unit 183, the inverse DCT conversion unit 184, The deblocking filter 186, the motion compensation unit 188, and the frame memory 187 may not be used at least in part.

  When the reception state of the full-segment broadcast is improved again and the one-segment broadcast returns to the full-segment broadcast (state C), the full-segment decoder 17 and the pattern detection unit 181 and the buffer 189 of the one-segment broadcast processing system are the same as in the state A. The other parts, that is, the variable length decoding unit 182, the inverse quantization unit 183, the inverse DCT conversion unit 184, the deblocking filter 186, the motion compensation unit 188, and the frame memory 187 do not operate. .

(Sixth embodiment)
FIG. 21 is a diagram for explaining the operation of the sixth embodiment of the digital broadcast receiver according to the present invention. In the digital broadcast receiver that switches between full-segment broadcasting and one-segment broadcasting, in the sixth embodiment according to the present invention, when the full-segment broadcasting is decoded and output, the processing system of the one-segment broadcasting does not perform processing. The pattern detection unit 181 also does not operate. The ES output from the one-segment TS decoder is discarded as it is. Then, when switching from full segment broadcasting to one segment broadcasting, the pattern detection unit 181 of the processing system of the one segment broadcasting operates, and when an IDR picture is detected from the received stream, decoding is performed from the IDR picture and the decoding stream of the one segment broadcasting is detected. Switch to display. Until the display is switched to the one-segment broadcasting display, the process of displaying the full-segment broadcasting is continued regardless of whether there is an error. Therefore, in the present embodiment, the one-segment processing system buffer 189 is not necessary, and the processing of the present embodiment can be executed using the configuration of the conventional one-segment decoder.

  For example, it is assumed that full segment broadcasting is decoded and output in the state A of FIG. In this state A, stream accumulation processing and decoding processing are not performed in the one-segment broadcasting processing system, and the operation of the pattern detection unit 181 is also stopped.

  Next, when the digital broadcast receiver is switched to the output of the one-segment broadcasting due to the deterioration of the reception quality of the full-segment broadcasting or the like in the state A, the digital broadcasting receiver shifts to the state B. When the reception quality of the full segment broadcast is deteriorated, the full segment broadcast cannot be decoded. However, even if it is determined that the reception quality has deteriorated and the timing for switching from full-segment broadcasting to one-segment broadcasting has passed, output of full-segment broadcasting is continued. In this case, full segment broadcast output processing is performed regardless of whether there is an error in the decoded image.

  When it is determined that reception quality of the full-segment broadcasting is deteriorated, the pattern detection unit 181 operates in the one-segment broadcasting processing system to detect an IDR picture from the input one-segment broadcasting stream. When an IDR picture is detected from the stream, normal decoding is started from the picture from the IDR, and the stream is switched from the displayed full-segment broadcast to the one-segment broadcast stream. Here, it is not necessary to search for an IDR picture from the one-segment broadcasting at the time of switching, and decoding is started from the point in time when the IDR picture is detected from the input stream of the one-segment broadcasting. It is possible to make the display without.

  When switching from the state where the one-segment broadcasting is being output (state B) to the output of the full-segment broadcasting again due to the improvement of the reception state, the state transitions to the state C. In state C, the full-segment broadcasting stream is decoded, and when the output becomes possible, the one-segment broadcasting is switched to the full-segment broadcasting. Full segment broadcasting can be decoded from the I picture of the stream and displayed. In the state C in which the full segment broadcasting is being output, the decoding process including the pattern detection unit 181 is stopped in the one segment broadcasting as in the state A.

  According to the processing of this embodiment, when full-segment broadcasting is output, the operation is stopped in the processing system of one-segment broadcasting, so that power consumption can be reduced compared to normal decoding processing of one-segment broadcasting.

FIG. 22 is a flowchart for explaining the flow of processing in the sixth embodiment of the digital broadcast receiver according to the present invention.
The digital broadcast receiver 1 monitors the reception quality while receiving full-segment broadcasting. If the reception quality of full-segment broadcasting deteriorates (step S141—No), the encoded stream data is input to the pattern detection unit 181 of the one-seg decoder 18 (step S142), and the pattern detection unit 181 inputs the IDR picture. The head is detected (step S143). If the head of the IDR picture is not detected, data input to the pattern detection unit 181 is continued. When the head of the IDR picture is detected (step S143-Yes), the variable length decoding unit 182 of the one-segment decoder 18 performs variable length decoding (step S144), and the inverse quantization unit 183 performs inverse quantization ( In step S145), the inverse DCT transform unit 184 performs inverse DCT transform (step S146). Next, if it is inter-frame prediction (step S147-Yes), motion compensation processing is performed (step S148), and deblocking filter processing is performed (step S149). If it is not inter-frame prediction (step S147-No), the deblocking filter process is performed as it is (step S149). And the data which performed the deblocking filter process are displayed (step S150).

  If the full-seg broadcast reception quality has not recovered (step S151-No), data is further input to the pattern detection unit 181 (step S152), and the decoding / display processing following step S144 is continued. Also, if the reception quality of full-segment broadcasting is recovered in step S151, the process waits as it is (step S141), and the processing of the one-segment processing system is resumed when the reception quality of full-segment broadcasting deteriorates.

  FIG. 23 is a diagram showing an example of control timing of the decoder unit in the sixth embodiment of the digital broadcast receiver according to the present invention. First, when a full-segment broadcast stream is decoded and output under the control of the tuner (state A), the full-segment decoder 17 is operating. In the processing system of the one-segment broadcasting, a pattern detection unit 181, a variable length decoding unit (VLD) 181, an inverse quantization unit (IQ) 183, an inverse DCT conversion unit (IDCT) 184, a deblocking filter (DF) 186, motion compensation The unit (MC) 188 and the frame memory 187 are not operating.

When the reception status of full-segment broadcasting deteriorates and the output is switched from full-segment broadcasting to one-segment broadcasting (state B), the operation of full-segment decoder 17 continues and the decoding process is continued regardless of whether there is a decoding error or not. To display.
Also, in the one-seg broadcast processing system, when the pattern detection unit 181 operates when switching to the state B and an IDR picture is detected, the subsequent one-seg broadcast stream is decoded. That is, the variable length decoding unit 182, the inverse quantization unit 183, the inverse DCT conversion unit 184, the deblocking filter 186, the motion compensation unit 188, and the frame memory 187 operate. If the decoding of the one-segment broadcasting is started, the full-segment decoder 17 can be stopped.

  When the reception status of the full-segment broadcasting is improved again and the one-segment broadcasting returns to the full-segment broadcasting (state C), the full-segment decoder 17 operates in the same manner as in the state A, and the one-segment broadcasting processing system pattern detection unit 181 is variable. The operations of the long decoding unit 182, the inverse quantization unit 183, the inverse DCT conversion unit 184, the deblocking filter 186, the motion compensation unit 188, and the frame memory 187 are stopped.

FIG. 24 shows a digital broadcasting receiver according to the present invention. 3 is a flowchart for explaining an example of processing when detecting the head of an IDR picture based on H.264 / AVC. This processing example can be applied to each example of the first to sixth embodiments.
As described above, H.264 is an image encoding method for one-segment broadcasting. H.264 / AVC is used. H. In H.264 / AVC, an IDR picture is used as a key frame that can be decoded independently. The pattern detection unit 181 of the one-segment decoder 18 performs IDR picture detection according to the following processing example.

  The pattern detection unit 181 of the one-segment decoder 18 analyzes the TS header of the input one-segment broadcast stream (step S161). Then, it is determined whether or not the beginning of the payload in the TS is a PES (Packetized Elementally Stream) header 0x000001 (step S162). If the beginning of the payload corresponds to the PES header, the beginning position of the PES payload (ES (Elementally Stream)) is detected (step S163).

  Next, it is determined from the head of the PES payload whether or not a NAL (Network Abstraction Layer) unit start code 0x000001 is included (step S164). If the start code is included in the PES payload, it is next determined whether or not the nal unit type is an AU (Access Unit Delimiter) delimiter (step S165). That is, it is determined whether or not the LSB 5 bit (MSB FIRST) of the byte next to the NAL start code is the AU identifier 9.

If nal unit type is the AU delimiter, it is determined whether primary pic type = 0 (step S166). That is, it is determined whether or not the upper 2 bits (MSB FIRST) of the next byte next to the NAL start code are 0. Here, if primary pic type = 0, it can be determined that it is the head of the IDR picture (step S167).
If the answer is NO in any of steps S162, S164, S165, and S166, it can be determined that the head is not the head of the IDR picture (step S168).

  In each of the above-described embodiments, an example has been described in which broadcasting services for full-segment broadcasting and one-segment broadcasting are provided by simultaneous broadcasting. However, the operation of each embodiment is not limited to simultaneous broadcasting, and full-segment broadcasting, one-segment broadcasting, Even if the program is different, it can be applied. In this case, the user can confirm the broadcast content of the switching destination at an early stage, and can determine at an early stage whether further channel switching is necessary.

  In addition, each of the above embodiments is applicable not only to switching between full-segment broadcasting and one-segment broadcasting, but also to switching operation between a reception function of one-segment (or full-segment) broadcasting and a function for operating an application such as e-mail. can do. For example, when switching to the operation screen of an application such as e-mail while watching 1Seg broadcast, when returning to viewing of 1Seg broadcast again, the decoding system of 1Seg broadcast is stopped while the application operation screen is displayed. However, although a power saving effect is obtained, it is impossible to quickly return to one-segment broadcasting. On the other hand, by applying the operation of the embodiment of the present invention, while displaying an operation screen of an application such as e-mail, an encoded stream between key frames of one-segment broadcasting (or full-segment broadcasting) is stored in a buffer. (Embodiments 1, 4 and 5) Alternatively, key frames are saved in a buffer (Embodiment 2), or decoded data of key frames is saved in a frame memory (Embodiment 3). When switching to broadcasting (or full segment broadcasting), it is possible to immediately switch and display using these stored data.

  In addition, each of the above embodiments can be applied not only to switching between full-segment (12 segments) and one-segment (1-segment) broadcasting services, but also to switching SD broadcasting using four segments. For example, when a 4-segment SD broadcast is being broadcast at the same time and one of the SD broadcasts is being output, the processing of each of the above embodiments is executed when switching to one-segment broadcasting. can do. The same applies when switching from one-segment broadcasting to SD broadcasting.

  Also, in a digital broadcast receiver equipped with two one-segment tuners and a digital broadcast receiver equipped with two full-segment tuners, the above-mentioned operation is also performed when switching between one-segment broadcast services or when switching between full-segment broadcast services. The operation of each embodiment can be applied. In these cases, broadcast programs are switched mainly by user operations. At this time, the digital broadcast receiver stores the key frame of the broadcast service program that is not output, or the stream between the key frames in a buffer or frame memory, and when the program is switched mainly by a user operation, Switch quickly using data stored in the buffer or frame memory.

  In such a case, the channel of the broadcast program that is not output may be determined in advance. However, the channel after switching is predicted, and the broadcast program of the channel is changed between key frames and key frames. You may make it perform the process which preserve | saves a stream to a buffer or a frame memory. As an example of a channel prediction method after switching, a digital broadcast receiver may store a channel selection tendency immediately before by a user and predict a channel as a next switching candidate according to the trend. For example, when performing channel selection by toggle, if the past channel selection by the user was performed in ascending order, the next channel is estimated as a switching candidate in ascending order with respect to the current channel, and for the broadcast program of that channel, Performs processing to save keyframes and streams between keyframes in a buffer or frame memory. A similar prediction can be made when the user's past channel selection is in descending order.

In addition, in the digital broadcast receiver of the above-described embodiment capable of switching between full-segment broadcasting and one-segment broadcasting and outputting the same, it may be possible to synchronize the appearance with the one-segment broadcasting by giving a delay to the full-segment broadcasting stream.
In full-segment broadcasting and one-segment broadcasting, even when the same program is being broadcast, the digital broadcasting receiver displays video images later than full-segment broadcasting in normal one-segment broadcasting. This is because the one-seg broadcast is transmitted later in the broadcast wave itself, and the video display of the one-seg broadcast is delayed in time due to the decoding delay in the one-seg decoder. Although this delay time cannot be generally described, for example, when watching full-segment broadcasting and one-segment broadcasting simultaneously on a television, one-segment broadcasting is displayed with a delay of about 2 seconds.

In order to eliminate the time delay as described above, a buffer is provided in the digital broadcast receiver to delay the full-segment broadcast stream, for example, by about 2 seconds, thereby eliminating the time delay between the full-segment broadcast and the one-segment broadcast, When the output of full-segment broadcasting and one-segment broadcasting is switched, switching without a sense of incongruity can be performed.
In other words, by providing the digital broadcast receiver with means for delaying the output of the multi-segment broadcast signal for a predetermined time, the output of the multi-segment broadcast and the one-segment broadcast in which a time difference until the output occurs when the same program is being broadcast The time difference can be eliminated.

DESCRIPTION OF SYMBOLS 1 ... Digital broadcast receiver, 10 ... Antenna, 11 ... Full segment tuner, 12 ... One segment tuner, 13 ... Full segment OFDM demodulator, 14 ... One segment OFDM demodulator, 15 ... Full segment TS decoder, 16 ... One segment TS decoder, 17 ... Full segment Decoder, 18 ... One-segment decoder, 19 ... Video switching unit, 20 ... Display unit, 21 ... Control unit, 22 ... Operation input unit, 100 ... Mobile phone, 101 ... Display unit, 102 ... Key input unit, 171 ... Variable length decoding 172 ... inverse quantization unit, 173 ... inverse DCT unit, 174 ... addition unit, 175 ... motion compensation unit, 176 ... frame memory, 181 ... pattern detection unit, 182 ... variable length decoding unit, 183 ... inverse quantization unit 184: Inverse DCT transform unit, 185 ... Adder unit, 186 ... Deblocking filter, 187 ... Frame memory, 188 ... Motion償部, 189 ... buffer.

Claims (12)

In a digital broadcast receiver comprising: means for receiving and decoding a digital broadcast signal; and means for selecting and outputting at least one of a plurality of types of image sources including the decoded digital broadcast signal.
A key that can be independently decoded from the stream of digital broadcast signals that are received and not selected as an output target when one of the plurality of types of image sources is selected and output. Means for detecting and storing the frame;
A digital broadcast receiver characterized in that, when selection of the output target is switched to the digital broadcast signal, output is performed using the stored key frame. The digital broadcast receiver according to claim 1, wherein
The means for receiving and decoding the digital broadcast signal includes a tuner unit for selecting the digital broadcast, a demodulator unit for demodulating the digital broadcast channel selected by the tuner unit, and a digital broadcast signal demodulated by the demodulator unit. A decoding unit for decoding,
The decoding unit includes a key frame detection unit that detects the key frame from the stream of the input digital broadcast signal;
A frame memory for decoding and storing the key frame detected by the key frame detection unit while updating to the latest key frame in time,
When the selection of the output target is switched to the digital broadcast signal, the decoded key frame stored in the frame memory is read and output,
A digital broadcast receiver characterized in that, when the next key frame is detected from the selected digital broadcast signal during the output, the stream from the next key frame is decoded and output. The digital broadcast receiver according to claim 1, wherein
The means for receiving and decoding the digital broadcast signal includes a tuner unit for selecting the digital broadcast, a demodulator unit for demodulating the digital broadcast channel selected by the tuner unit, and a digital broadcast signal demodulated by the demodulator unit. A decoding unit for decoding,
The decoding unit includes a key frame detection unit that detects the key frame from the stream of the digital broadcast signal, and a buffer that stores a stream including the key frame detected by the key frame detection unit in an undecoded state. And
The stream from the key frame detected from the stream of the digital broadcast signal to the stream immediately before the next key frame detected in time is stored in the buffer without being decoded, and the stream stored in the buffer is always Update it to be a stream up to just before the latest keyframe,
A digital broadcast receiver characterized in that when the selection of the output target is switched to the digital broadcast signal, a stream including a key frame stored in the buffer is read, decoded, and output. The digital broadcast receiver according to claim 1, wherein
The means for receiving and decoding the digital broadcast signal includes a tuner unit for selecting the digital broadcast, a demodulator unit for demodulating the digital broadcast channel selected by the tuner unit, and a digital broadcast signal demodulated by the demodulator unit. A decoding unit for decoding,
The decoding unit stores a key frame detection unit that detects the key frame from the stream of the digital broadcast signal, and updates the key frame detected by the key frame detection unit to the latest key frame without decoding. And a buffer to
When the selection of the output target is switched to the digital broadcast signal, the key frame stored in the buffer is read out and decoded, and the next key frame is selected from the selected digital broadcast signal during the output. A digital broadcast receiver, wherein if detected, the next key frame is decoded and output. The digital broadcast receiver according to claim 1, wherein
The means for receiving and decoding the digital broadcast signal includes a tuner unit for selecting the digital broadcast, a demodulator unit for demodulating the digital broadcast channel selected by the tuner unit, and a digital broadcast signal demodulated by the demodulator unit. A decoding unit for decoding,
The decoding unit includes a key frame detection unit that detects the key frame from the stream of the digital broadcast signal, and a buffer that stores a stream including the key frame detected by the key frame detection unit in an undecoded state. The stream from the key frame detected from the digital broadcast signal stream to the time immediately before the next key frame detected in time is stored in the buffer in a state where it is not decoded, and the stream is stored in the buffer. Is always updated to the stream immediately before the latest keyframe,
When the selection of the output target is switched to the digital broadcast signal, the stream including the key frame stored in the buffer is read out, decoded and output while fast-forwarding, and the selection is made after the buffer becomes empty A digital broadcast receiver that decodes and outputs a stream of the digital broadcast signal. The digital broadcast receiver according to claim 1, wherein
The means for receiving and decoding the digital broadcast signal includes a tuner unit for selecting the digital broadcast, a demodulator unit for demodulating the digital broadcast channel selected by the tuner unit, and a digital broadcast signal demodulated by the demodulator unit. A decoding unit for decoding,
The decoding unit includes a key frame detection unit that detects the key frame from the stream of the digital broadcast signal, and a buffer that stores a stream including the key frame detected by the key frame detection unit in an undecoded state. The stream from the key frame detected from the digital broadcast signal stream to the time immediately before the next key frame detected in time is stored in the buffer in a state where it is not decoded, and the stream is stored in the buffer. Is always updated to the stream immediately before the latest keyframe,
When the selection of the output target is switched to the digital broadcast signal, the decoding unit reads a stream including the key frame stored in the buffer, and the decoding unit performs decoding faster than the decoding performed by the decoding unit during normal output. A digital broadcast receiver which performs processing and discards and decodes and outputs a stream of a selected digital broadcast signal after the buffer becomes empty. In a digital broadcast receiver comprising: means for receiving and decoding a digital broadcast signal; and means for selecting and outputting at least one of a plurality of types of image sources including the decoded digital broadcast signal.
The means for receiving and decoding the digital broadcast signal includes a tuner unit for selecting the digital broadcast, a demodulator unit for demodulating the digital broadcast channel selected by the tuner unit, and a digital broadcast signal demodulated by the demodulator unit. A decoding unit for decoding,
When the selection of an output target is switched from any one of the plurality of types of image sources to the digital broadcast signal, the decryption unit can independently decode a key frame from the selected digital broadcast signal stream. And decoding and outputting the stream of the digital broadcast signal from the detected key frame,
Until the stream of the digital broadcast signal is decoded, the output of any one of the plurality of types of image sources is maintained, and when the stream from which the digital broadcast signal is decoded is decoded, A digital broadcast receiver characterized in that the output is switched from any one to the digital broadcast signal. In the digital broadcast receiver according to any one of claims 1 to 7,
As means for receiving and decoding the digital broadcast signal, means for receiving and decoding a one-segment broadcast signal assigned to one segment in a frequency band; and receiving a multi-segment broadcast signal using a plurality of segments Means for decoding,
Switching from the multi-segment broadcast signal to the one-segment broadcast signal is switching of the output target selection. In the digital broadcast receiver according to any one of claims 1 to 7,
As means for receiving and decoding the digital broadcast signal, there are a plurality of means for receiving and decoding a one-segment broadcast signal assigned to one segment in a frequency band, or a multi-segment broadcast signal using a plurality of segments A plurality of means for receiving and decoding
The digital broadcast receiver characterized in that switching between the one-segment broadcast signals or switching between the plurality of segment broadcast signals is switching of the selection of the output target. In the digital broadcast receiver according to any one of claims 1 to 7,
As the plurality of types of image sources, an image source generated by a specific application operating on the digital broadcast receiver can be output,
A digital broadcast receiver characterized in that switching from output of an image source generated by the application to the digital broadcast signal is switching of selection of the output target. The digital broadcast receiver according to any one of claims 3 to 6,
When the selection of the output target is switched to the digital broadcast signal, until the stream including the key frame stored in the buffer is decoded and output, the output of any of the plurality of types of image sources is performed. A digital broadcast receiver characterized by continuously preventing output from being interrupted. The digital broadcast receiver according to claim 8, wherein
Means for delaying the output of the multi-segment broadcast signal by a predetermined time, and eliminating the time difference between the output of the multi-segment broadcast signal and the one-segment broadcast signal that causes a time difference until the output when broadcasting the same program A digital broadcast receiver characterized by that.

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