JP2002058023A - Encoding picture signal transmitting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To overcome the problem such that the length of a program is pro longed and a black picture is displayed at the time of switching since black data for one GOP, which is not originally required whenever a picture signal is switched, is inserted although the occurrence of noise against a decoding picture can be prevented. SOLUTION: When a control unit 28 gives the instruction of the switch of a bit stream, the encoding system of the bit stream of a switch candidate is detected, a replacement bit stream in a system similar to the encoding system is generated and a part of the bit stream after a switch point is replaced with the replacement bit stream.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an encoded image signal transmission system for outputting a bit stream of an encoded image signal.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a configuration diagram showing a conventional encoded image signal transmission system disclosed in Japanese Patent Application Publication No. 9-209, in which 1 is an image signal transmission device, 2 is an MPEG encoder that encodes image signals,
Is a data storage unit for storing an image signal encoded by the MPEG encoder 2, and 4 is a first signal such as a program among image signals encoded by the MPEG encoder 2.
A temporary data storage unit 5 for temporarily storing the image signal of the first video signal temporarily stores a second image signal such as a CM broadcasted during a program among the image signals encoded by the MPEG encoder 2. This is a temporary data storage unit.

A black data generator 6 generates black data.
Reference numeral 7 denotes an MPEG encoder for encoding the black data generated by the black data generation unit 6, and reference numeral 8 denotes an MPEG encoder 7.
Is a data storage unit for storing a third image signal, which is black data encoded according to (1), 9 is a picture number conversion unit for converting a picture number, and 10 is a picture type identification unit for identifying a picture type. Reference numeral 11 denotes a switch for selecting and outputting a first image signal, a second image signal, or a third image signal under the instruction of the control unit 12, reference numeral 12 denotes a control unit for controlling the switch 11 and the like, and reference numeral 13 denotes a switch 11 Is an MPEG decoder that decodes the image signal output from.

Next, the operation will be described. This coded image signal transmission system is for switching and transmitting an image signal compressed and coded according to the MPEG standard on a GOP (group of picture) basis at an arbitrary timing. First, the MPEG encoder 2 encodes the image signal and stores it in the data storage unit 3. At this time, the temporary data storage unit 4 temporarily stores, for example, a first image signal such as a program among the image signals encoded by the MPEG encoder 2, and the temporary data storage unit 5 Among the coded image signals, a second image signal such as a CM broadcast during a program is temporarily stored.

On the other hand, when the black data generator 6 generates black data, the MPEG encoder 7 encodes the black data generated by the black data generator 6 in a closed GOP format and converts the black data into a third image signal. And stored in the data storage unit 8.

Here, when the switch 11 selects and outputs the first image signal stored in the temporary data storage section 4, when switching from the first image signal to the second image signal, The control unit 12 controls the switch 11 as follows. That is, the last GOP in the first image signal
, The third image signal for one GOP is inserted. Next, a third image signal corresponding to the picture number of the second image signal is output instead of the data of the first group of inter-frame prediction encoded images in the second image signal, and thereafter,
The second image signal is transmitted. This allows
Even if the image signal is switched, the MPEG decoder 13
, Can be prevented from being generated in the decoded image.

[0007]

Since the conventional coded image signal transmission system is configured as described above, it is possible to prevent the occurrence of noise in the decoded image.
Each time an image signal is switched, black data for one GOP, which is not originally required, is inserted, so that the length of the program is extended and a black screen is displayed at the time of switching.

The present invention has been made to solve the above-described problems, and can prevent generation of noise due to switching of image signals without changing a program time or displaying a black screen. It is an object to obtain an encoded image signal transmission system.

[0009]

An encoded image signal transmission system according to the present invention detects a coding scheme of a bit stream as a switching candidate when a control unit instructs switching of a bit stream, and performs the coding. A replacement bit stream of the same system as the system is generated, and a part of the bit stream after the switching point is replaced with the replacement bit stream and output.

[0010] The coded image signal transmission system according to the present invention differs from the bit stream according to the present invention only when the frame of the bit stream after the switching point refers to the frame of the bit stream before the switching point. In this case, the output is replaced with a replacement bit stream.

[0011] In the coded image signal transmission system according to the present invention, when a coding scheme of a bit stream to be switched is given from the outside, detection processing of the coding scheme of the bit stream is stopped.

[0012] When handling an image signal having a group of picture structure encoded by the MPEG-2 system, the encoded image signal transmission system according to the present invention detects a boundary of the group of pictures and sets a bit at the boundary. This is an instruction to switch streams.

[0013] An encoded image signal transmission system according to the present invention is adapted for a case where a frame of a bit stream of an image signal has an open group of picture structure encoded with reference to a frame in a preceding group of pictures. As far as possible, the replacement bit stream that is MPEG-2 data is replaced.

In the coded image signal transmission system according to the present invention, when the frame data length of the bit stream before replacement is longer than the frame data length of the replacement bit stream, null information is represented in the replacement bit stream. A bit stream is added to make the frame data lengths before and after replacement equal.

[0015] A coded image signal transmission system according to the present invention is such that a coding method of a replacement bit stream, which is MPEG-2 data, is externally input to generate the replacement bit stream. It is.

In the coded image signal transmission system according to the present invention, when the control means reproduces the bit stream of the image signal from the middle, the control section detects the coding method of the bit stream and uses the same coding method as the coding method. A replacement bit stream is generated, and a part of the bit stream after the reproduction start point is replaced with the replacement bit stream and output.

[0017] The encoded image signal transmission system according to the present invention provides a bit stream related to a frame of a bit stream only after the frame of the bit stream after the reproduction start point refers to the frame of the bit stream before the reproduction start point. Is replaced with a replacement bit stream and output.

In the coded image signal transmission system according to the present invention, when an encoding method of a bit stream of an image signal is given from outside, detection processing of the encoding method of the bit stream is stopped.

When handling an image signal having a group of picture structure encoded by the MPEG-2 system, the encoded image signal transmission system according to the present invention detects a boundary of the group of pictures and sets a bit at the boundary. This is an instruction to output a stream.

[0020] An encoded image signal transmission system according to the present invention provides a method for transmitting an encoded image signal in a case where a frame of a bit stream of an image signal has an open group of picture structure encoded with reference to a frame in a preceding group of pictures. As far as possible, the replacement bit stream that is MPEG-2 data is replaced.

In the encoded image signal transmission system according to the present invention, when the frame data length of the bit stream before replacement is longer than the frame data length of the replacement bit stream, null information is represented in the replacement bit stream. A bit stream is added to make the frame data lengths before and after replacement equal.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a configuration diagram showing an encoded image signal transmission system according to Embodiment 1 of the present invention. In the figure, reference numeral 21 denotes an encoding of a first image signal and a bit stream of the first encoded image signal. An output image encoding device 22 is an image encoding device that encodes a second image signal and outputs a bit stream of the second encoded image signal.

Reference numeral 23 denotes a frame information detecting unit for detecting the boundary of each frame in the bit stream of the first encoded image signal and the encoding system of each frame, and 24 denotes a start of decoding in the bit stream of the first encoded image signal. A decoding time information detecting unit for detecting information on timing and display time; 25, a frame information detecting unit for detecting a boundary of each frame in the bit stream of the second encoded image signal and an encoding method of each frame; The decoding time information detection unit detects information on the decoding start timing and the display time in the bit stream of the coded image signal of No. 2.

Reference numeral 27 denotes a coded replacement data generation unit for generating a replacement bit stream; 28, a control unit for controlling each processing unit in the coded image signal transmission system; 29, a bit stream of the coded image signal A storage unit for storing information of each frame therein, a switching unit (selection unit) 30 for selecting and outputting an arbitrary bit stream under the instruction of the control unit 28, and a coding unit 31 output from the switching unit 30 An image decoding device that decodes an image signal. The frame information detection units 23 and 25, the decoding time information detection units 24 and 26, the replacement encoded data generation unit 27, the control unit 28, and the storage unit 29
Control means.

FIG. 2 is an explanatory diagram showing a configuration example of a bit stream by the encoded image signal transmission system. In the figure, (1) is a bit stream of a first encoded image signal, and (2) is a bit stream of a second encoded image signal. In this example, each of the bit streams (1) and (2) is used as an encoding method for each frame, and an intra-frame encoding method for encoding using only image data of the encoding target frame, and an encoding method for the encoding target frame. On the other hand, a case is shown in which the moving image is encoded by a moving image encoding method that employs inter-frame predictive encoding that encodes difference data from frames located forward and / or backward when rearranged in display order. Further, the _119B frame in the bit stream of (1) is the 19th frame in the display order, and indicates that the frame is encoded by the inter-frame predictive encoding method. Further, arrows described by solid lines indicate a reference relationship at the time of encoding each frame, for example,
(1) is 1 _19B of the frame in the bit stream indicates that it is referring to encode each frame of 1 _18I, 1 _21P.

(3) is a bit stream obtained when the bit stream (1) is simply switched to the bit stream (2) at the time (A).
In the bit stream of (3), the 2 _15P frame in the bit stream after the switching time (A) referred to at the time of encoding of the 2 _16B and 2 _17B frames is changed to _{115 P} by stream switching. 2
_When decoding _16B and _217B frames, noise is generated due to obtaining unexpected decoded images.

(4) is a replacement bit stream that replaces a part of the original bit stream when the bit stream is switched. Here, when the replacement bit stream (4) is switched from the bit stream (1) to the bit stream (2), for example, in the bit stream (2) output after the switching, in the bit stream before the switching point, This is a bit stream for replacing with a bit stream of one or more frames obtained by referring to a frame and performing inter-frame difference prediction encoding. Therefore,
The replacement bit stream (4) is a bit stream corresponding to a frame coded according to the same coding scheme as the bit stream (2) of the second coded image signal, but is coded when each frame is coded. Bits coded with reference to only intra-coded frames that are positioned forward when rearranged in the display order with respect to the target frame and that are positioned after the frame to be coded in the bit stream. It is a stream. In order to prevent the occurrence of an error when decoding the bit stream by the image decoding device 31, information on the frame decoding start timing and the display time is replaced with the replacement bit stream (4) of the bit stream (2) before the replacement. Generate as a stream that matches the frame.

(5) is a bit stream output from the coded image signal transmission system when switching from the bit stream (1) to the bit stream (2) at the time (A). In the bit stream (5), 2 in the bit stream after the switching time (A)
_16B, the 2 _17B 2 two frames, 3 _1B, 3 by replacing the _2B, the time since the frame that references a 2 _15P frames included in the previous bit stream than (A) is eliminated, the noise during decoding Does not occur.

Next, the operation will be described. Hereinafter, a case will be described in which the bit stream (1) of the first encoded image signal such as a program is switched to the bit stream (2) of the second encoded image signal such as a CM.

The first bit stream (1) of a program or the like encoded by the external image encoding device 21 is, for example, a frame information detecting unit 23 of the encoded image signal transmission system.
And the decryption time information detection unit 24. The frame information detection unit 23 detects a frame boundary from the first bit stream (1), detects a position of the frame encoded by the intra-frame encoding method, and
Notify 8. The decoding time information detecting unit 24 detects a parameter affecting the decoding timing at the time of decoding from the first bit stream (1) and notifies the control unit 28 of the parameter.

Similarly, the second bit stream (2) such as a CM encoded by the external image encoding device 22 is transmitted to the frame information detecting section 25 and the decoding time information detecting section 26 of the encoded image signal transmitting system. Is input to The frame information detecting unit 25 outputs the second bit stream (2)
, And the position of the frame encoded by the intra-frame encoding method is detected and notified to the control unit 28. The decoding time information detection unit 26 detects a parameter that affects the decoding timing at the time of decoding from the second bit stream (2), and notifies the control unit 28 of the parameter.

When the control unit 28 receives the second bit stream (2), it analyzes the coding method such as the number of pixels and the frame rate of the frame in the second bit stream (2) and determines the same as the coding method. , That is, the replacement bit stream (4) is instructed to the replacement coded data generation unit 27.

The replacement coded data generator 27 generates a replacement bit stream (4) in accordance with the coding method specified by the controller 28. The replacement bit stream (4) generated at this time is located forward when the encoding target frame is rearranged in the display order, and is located later than the encoding target frame in the bit stream. It encodes the difference data from the frame. Also, the bit stream is one or more frames encoded by an inter-frame difference prediction encoding method in which the difference data from the referenced frame is set to zero so that the data length is minimized.

The control unit 28 instructs the replacement coded data generation unit 27 in advance with parameters that affect the decoding start timing of the second bit stream (2) acquired from the decoding time information detection unit 26. As a result, a parameter that affects the decoding start timing of the replacement bit stream (4) is generated as a stream equal to the second bit stream (2).

Next, the control unit 28 encodes the first bit stream (1) and the second bit stream (2) detected by the frame information detection units 23 and 25, respectively, using the intra-frame encoding method. By instructing the switching unit 30 to select the second bit stream (2) at the timing immediately before the frame, the switching from the first bit stream (1) to the second bit stream (2) is performed. Let it do.

However, when switching the bit stream, the control unit 28 switches so that a part of the second bit stream (2) after the switching point is replaced with the replacement bit stream (4) and output. Instruct the unit 30. That is, the inter-frame difference prediction coding located in the bit stream is between the switching point of the bit stream and the first intra-coded frame located after the switching point when rearranged in the display order. The switching unit 30 replaces the bit streams of all the frames that have been output with the replacement bit stream (4) described above.
To instruct.

FIG. 3 is a flowchart showing a bit stream replacement process performed by the control unit 28 after the switching point.
3, the control unit 28 includes a frame information detection unit 25.
Each time a frame boundary is detected from the bit stream, the position in the bit stream from the switching point in frame units, the position when rearranged in display order, and the encoding method are stored for each frame. 29.

Then, the control unit 28, based on the frame position from the switching point stored in the storage unit 29, performs intra-frame encoding which is located first after the switching point when rearranging the switching point and display order. When the inter-frame prediction difference coded frame located in the bit stream is detected between the current frame and the detected frame, the switching unit 30 is instructed to select the replacement bit stream (4) to replace the bit stream. I do. In addition, the control unit 28 instructs the switching unit 30 to select the second bit stream (2) so that the frames after the appearance of the above-described intra-coded frame are not replaced.

According to the above operation, the bit stream output from the coded image signal transmission system refers to the frame included in the bit stream before the switching point in the bit stream after the switching point. Frames can be eliminated. Note that the same operation may be performed when switching from the second bit stream (2) to the first bit stream (1).

As is apparent from the above, according to the first embodiment, the bit stream output from the coded image signal transmission system includes the bit stream before the switching point in the bit stream after the switching point. Since there is no frame that refers to a frame included in the stream, it is possible to suppress noise at the time of decoding due to a mismatch between the reference frame at the time of encoding and decoding at the time of decoding of the stream.

Further, the replacement bit stream (4) is
Since the difference between the input coded image signal and the input coded image signal is zero, the frame immediately after switching is displayed as a still image for one or more frames during decoding, and no specific frame unique to the device is displayed.

Since a bit stream of a frame that does not exist in the original input bit stream is not inserted as in the conventional example, an unnecessary frame is inserted every time the input signal is switched, and the program time is reduced. It does not grow. Furthermore, even when switching from the second bit stream (2) to the first bit stream (1), the same operation is performed, so that no noise occurs even if the switching is repeated.

Embodiment 2 In the first embodiment described above, a part of the second bit stream (2) after the switching point is replaced with the replacement bit stream (4) to be output, but the second bit stream after the switching point is output. Only when the frame of the stream (2) refers to the frame of the bit stream before the switching point, the bit stream related to the frame is replaced with the replacement bit stream (4).
May be output.

Next, the operation will be described. Hereinafter, a case where the bit stream (1) of the first encoded image signal such as a program is switched to the bit stream (2) of the second encoded image signal such as a CM will be described. In the following description, an operation of switching from the bit stream (1) to the bit stream (2) will be described. Conversely, a similar operation may be performed when switching from the bit stream (2) to the bit stream (1).

FIG. 4 is a flowchart showing a bit stream replacement process performed by the control unit 28 after the switching point.
In the figure, each time the frame information detection unit 25 detects a frame boundary from within a bit stream, the control unit 28 rearranges the position in the bit stream from the switching point in units of frames and the display order. Is stored in the storage unit 29 for each frame.

Then, based on the frame position from the switching point stored in the storage unit 29, the control unit 28 performs intra-frame encoding that is located first after the switching point when rearranging the switching point and the display order. When a frame located in the bit stream is detected between the current frame and the current frame, the position of the frame referred to at the time of encoding is determined from the encoding information of the frame acquired from the frame information detection unit 25 before the switching point. It is determined whether the frame is a frame.

At this time, when the control unit 28 determines that the frame before the switching point is being referred to, the switching unit 30 selects the replacement bit stream (4) to replace the bit stream. Although it is instructed, when it is determined that the frame before the switching point is not referred to, the switching unit 30 is instructed to select the bit stream (2) so as not to perform the replacement. The same operation may be performed when switching from the bit stream (2) to the bit stream (1).

With the above configuration, the same effects as in the first embodiment can be obtained, and when the frame of the bit frame before the switching point is not referred to, the bit stream relating to the frame is replaced. It is not replaced with the use bit stream (4). Therefore, even when the bit stream is switched, it is possible to prevent the frame immediately after the switching during decoding from being displayed as a still image for one or more frames.

Embodiment 3 FIG. 5 is a block diagram showing an encoded image signal transmission system according to Embodiment 3 of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will be omitted. Reference numeral 32 denotes an encoding system input unit (control means) for externally inputting the encoding system of the replacement bit stream (4).

Next, the operation will be described. In the first embodiment, when the bit stream is switched, the encoding method of the second bit stream (2) is automatically determined, and the same encoding method as the encoding method is designated to replace the bit stream (2). 4) was generated.
When the encoding scheme of the replacement bit stream (4) is given from outside, the replacement bit stream (4) is generated according to the encoding scheme, and the encoding scheme of the second bit stream (2) is changed. The determination process may be omitted.

Hereinafter, as in the first embodiment, the bit stream (1) of the first coded image signal such as a program is changed from the bit stream (2) of the second coded image signal such as a CM. The operation for switching will be described. Conversely, the same operation may be performed when switching from bit stream (2) to bit stream (1).

The first bit stream (1) such as a program encoded by the external image encoding device 21 is input to the frame information detecting section 23 of the encoded image signal transmitting system. The frame information detection unit 23 detects a frame boundary from the first bit stream (1), detects a position of the frame encoded by the intra-frame encoding method, and notifies the control unit 28 of the detected position.

Similarly, a second bit stream (2) such as a CM encoded by the external image encoding device 22
Is a frame information detector 2 of the encoded image signal transmission system
5 is input. The frame information detection unit 25 detects a frame boundary from the second bit stream (2), detects a position of the frame encoded by the intra-frame encoding method, and notifies the control unit 28 of the detected position.

When the coding system input unit 32 externally inputs the coding system of the replacement bit stream (4), the control unit 28 determines whether the generation of the replacement bit stream (4) by the coding system is different. It instructs the substitute encoded data generation unit 27. The replacement coded data generation unit 27 generates a replacement bit stream (4) according to the coding method. The stream generated at this time is positioned forward when rearranged in the display order with respect to the encoding target frame, and encodes difference data from a frame located behind the encoding target frame in the bit stream. Is what you do. In addition, the bit stream is one or a plurality of bit streams encoded by an inter-frame difference prediction encoding method in which the difference data from the referenced frame is set to zero so that the data length becomes the shortest.

Hereinafter, by switching from the bit stream (1) to the bit stream (2) by the same operation as in the first embodiment, the bit stream output from the encoded image signal transmission system is switched from the switching point. In the subsequent bit stream, it is possible to eliminate a frame that refers to a frame included in the bit stream before the switching point. The bit stream (2)
The same operation may be performed when switching from to the bit stream (1).

With the above-described configuration, if the information on the encoding method and the decoding start timing of the input encoded image signal, such as the number of pixels of the frame and the frame rate, is known, the replacement bit is externally provided. By instructing the encoding method of the stream (4), the control unit 28
It is not necessary to detect the coding method of the input coded image signal such as the number of pixels of the frame or the frame rate, and the decoding time information detecting units 24 and 26 are provided for detecting the information on the decoding start timing and the display time. Without
The same effect as in the first embodiment can be obtained.

Embodiment 4 FIG. FIG. 6 is a configuration diagram showing an encoded image signal transmission system according to Embodiment 4 of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will be omitted. Reference numerals 41 and 42 denote MPEG-2 encoders for encoding an image signal according to the MPEG-2 system (a system defined by ISO / IEC 13818-2), and reference numeral 43 denotes a first MPEG-encoder encoded by the MPEG-2 encoder 41. GO in 2-bit stream
A GOP information detector for detecting the position and content of the P header,
44, a GOP information detector for detecting the position and content of the GOP header in the second MPEG-2 bit stream encoded by the MPEG-2 encoder 42;
Is an MPEG-2 decoder for decoding the MPEG-2 bit stream output from the switching unit 30. Note that G
The OP information detection units 43 and 44 constitute control means.

Next, the operation will be described. Hereinafter, a frame coded by an inter-frame predictive coding method for coding difference data from a frame located ahead of a current frame when rearranged in the display order is a P picture,
A frame coded by an inter-frame predictive coding method for coding differential data from a frame located in front and behind is encoded by a B-picture, an intra-frame coding method using only information on a frame to be coded. The resulting frame is called an I picture.

As in the first embodiment, a first MPEG-2 bit stream (1) such as a program
Second MPEG-2 bit stream such as CM (2)
The operation when switching to is described.

An MPEG-2 bit stream (1) such as a program encoded by an external MPEG-2 encoder 41 is input to a frame information detecting unit 23, a GOP information detecting unit 43, and a decoding time information detecting unit 24. . The frame information detection unit 23 detects a frame boundary from the MPEG-2 bit stream (1), detects a picture header of each frame, and notifies the control unit 28. The GOP information detection unit 43 detects the boundary position of the GOP in the bit stream and notifies the control unit 28. The decoding time information detection unit 24 outputs VBV_DELAY, PTS,
Each parameter of the DTS is detected and notified to the control unit 28.

Similarly, an external MPEG-2 encoder 4
The MPEG-2 bit stream (2) such as a CM coded by the C.2 is input to the frame information detecting unit 25, the GOP information detecting unit 44, and the decoding time information detecting unit 26. The frame information detection unit 25 detects a frame boundary from the MPEG-2 bit stream (2), detects a picture header of each frame, and
Notify 8. The GOP information detection unit 44 detects the boundary position of the GOP in the bit stream and notifies the control unit 28. The decoding time information detecting unit 26 outputs VBV_DELAY, P from the MPEG-2 bit stream (2).
Each parameter of TS and DTS is detected and notified to the control unit 28.

Upon input of the MPEG-2 bit stream (2), the control unit 28 analyzes, for example, a GOP header, a sequence header and a picture header, and
M encoded in the same manner as the 2-bit stream (2)
The replacement coded data generation unit 27 is instructed to generate the PEG-2 bit stream, that is, the replacement bit stream (4). The stream generated at this time is located when the encoding target frame is rearranged in the display order, and encodes difference data from a frame located after the encoding target frame in the bit stream. Things. In addition, the bit stream is one or a plurality of bit streams encoded by an inter-frame difference prediction encoding method in which the difference data from the referenced frame is set to zero so that the data length becomes the shortest.

The control unit 28 controls the MPEG-2 bit stream (2) acquired from the decoding time information detecting unit 26.
VBV_DELAY, PTS, and DTS parameters of the replacement bit stream (4) are instructed in advance to the replacement coded data generation unit 27.
AY, PTS, and DTS parameters are generated as a stream equal to the MPEG-2 bit stream (2).

Next, the control unit 28 controls the GOP information detection unit 4
At the timing in units of GOP boundaries in the MPEG-2 bit streams (1) and (2) detected by
By instructing the selection of the MPEG-2 bit stream (2), the MPEG-2 bit stream (1)
-Switch the bit stream (2).

FIG. 7 is a flowchart showing a bit stream replacement process by the control unit 28 after the switching point.
In the figure, when switching the bit stream, the control unit 28 compares the bit stream switching point with the MPEG-2 bit stream (2) after the switching point and the switching point after rearranging in the display order. The switching unit 30 replaces the bit streams of all the B pictures located in the bit stream up to the frame of the first I picture with a replacement bit stream (4). To instruct. The bit stream is not replaced after the first I-picture frame. The same operation may be performed when switching from the MPEG-2 bit stream (2) to the MPEG-2 bit stream (1).

With the above operation, the coded image signal transmission system can receive the coded image signal having the GOP structure coded according to the MPEG-2 system specified by ISO / IEC 13818-2 even if the coded image signal is input. The same effect as in the first embodiment can be obtained.

Embodiment 5 In the fourth embodiment, the MPEG-2 bit stream (2) after the switching point is partially replaced with the replacement bit stream (4) and output. However, the MPEG-2 bit stream after the switching point is output. Only when the stream frame has an open GOP structure encoded with reference to the frame in the preceding GOP, the replacement bit stream (4), which is MPEG-2 data, may be replaced. Good.

Next, the operation will be described. Hereinafter, a frame coded by an inter-frame predictive coding method for coding difference data from a frame located ahead of a current frame when rearranged in the display order is a P picture,
A frame coded by an inter-frame predictive coding method for coding differential data from a frame located in front and behind is encoded by a B-picture, an intra-frame coding method using only information on a frame to be coded. The resulting frame is called an I picture.

As in the fourth embodiment, for example, a first MPEG-2 bit stream (1) such as a program
Second MPEG-2 bit stream such as CM (2)
The operation when switching to is described. The operation is substantially the same as that of the fourth embodiment. However, in the fifth embodiment, the GOP information detectors 43 and 44 detect the boundary positions of GOPs in the MPEG-2 bit streams (1) and (2), and , GOP headers are detected and notified to the control unit 28.

FIG. 8 is a flowchart showing the bit stream replacement process by the control unit 28 after the switching point.
In the figure, when switching the bit stream, the control unit 28 performs the following replacement processing when the MPEG-2 bit stream (2) has an open GOP structure in which a frame is referred to during encoding across GOP boundaries. I do. That is, when rearranged in the display order with the switching point, after the switching point and before the frame of the first I picture, the bit stream of all the B pictures located in the bit stream is replaced with a difference. The replacement unit 30 is instructed to perform the replacement so as to replace the replacement bit stream (4).

Further, the control unit 28 does not replace the bit stream of a frame located later in the bit stream than the frame of the I picture located first when rearranged in the display order after the switching point. .
Furthermore, the GOP of the MPEG-2 bit stream (2)
When the CLOSED_GOP bit of the header is 1, the above replacement is not performed. The same operation may be performed when switching from the MPEG-2 bit stream (2) to the MPEG-2 bit stream (1).

With the above operation, the same effects as in the fourth embodiment can be obtained, and the MPEG-
When the two bit stream is encoded in the closed GOP format, the bit stream is not replaced, so that the frame immediately after switching during decoding is prevented from being displayed as a still image for one or more frames. Is obtained.

Embodiment 6 FIG. FIG. 9 is a configuration diagram showing an encoded image signal transmission system according to Embodiment 6 of the present invention. In the figure, the same reference numerals as those in FIG. 6 denote the same or corresponding parts, and a description thereof will be omitted. 46 is a frame size detecting unit for detecting the data length of each frame of the MPEG-2 bit stream (1), 47 is a frame size detecting unit for detecting the data length of each frame of the MPEG-2 bit stream (2), 48 is Replacement bit stream (4)
A frame size detecting unit for detecting the data length of each frame, a null data generating unit 49 for generating a null TS packet as null data, and a selecting unit 50 for selecting either the replacement bit stream (4) or the null TS packet. This is a switching unit for outputting. The frame size detectors 46 and 4
7, 48, the null data generating unit 49 and the switching unit 50 constitute a control unit.

Next, the operation will be described. A frame coded by an inter-frame predictive coding method for coding difference data from a frame positioned forward with respect to a frame to be coded when rearranged in the display order is a P picture, a frame positioned forward and backward. A frame coded by the inter-frame predictive coding method for coding the difference data of B is a B picture, and a frame coded by the intra-frame coding method using only the information of the coding target frame is I picture.
Let's call it a picture.

As in the fourth embodiment, for example, a first MPEG-2 bit stream (1) such as a program
Second MPEG-2 bit stream such as CM (2)
The operation when switching to is described. The rough operation is the same as that of the fourth embodiment, but the sixth embodiment
In this case, the frame size detection units 46 and 47 use the MPEG-2
The data length of each frame of the bit streams (1) and (2) is detected and notified to the control unit 28. Further, also for the replacement bit stream (4), the frame size detector 48 detects the data length of each frame and notifies the controller 28 of the data length.

The control unit 28 includes GOP information detection units 43 and 4
By instructing the switching unit 30 to select the MPEG-2 bit stream (2) at the timing in units of GOP boundaries in the MPEG 2 bit streams (1) and (2) detected by
The switching from the EG-2 bit stream (1) to the MPEG-2 bit stream (2) is performed.

FIG. 10 is a flowchart showing a bit stream replacement process by the control unit 28 after the switching point. In the figure, when switching the bit stream, the control unit 28 performs the following replacement processing when the MPEG-2 bit stream (2) has an open GOP structure in which a frame is referred to during encoding across GOP boundaries. I do. That is, when rearranged in the display order with the switching point, the replacement of the bit stream of all the B picture frames located in the bit stream between the switching point and the first I-picture frame is performed. The switching unit 30 is instructed to perform the replacement to replace the bit stream (4).

At this time, the control unit 28 compares the bit lengths of the B picture of the MPEG-2 bit stream (2) and the B picture of the replacement bit stream (4), and 4) B
If the data length of the picture is shorter, the switching unit 50
, A null TS packet is selected, a missing null TS packet is inserted after the B picture, and the data length of each frame is matched before and after replacement. Note that MP
The same operation may be performed when switching from the EG-2 bit stream (2) to the MPEG-2 bit stream (1).

With the above operation, the coded image signal transmission system always transmits at a constant bit rate, so that the bit stream is switched without causing a failure such as overflow or underflow of the VBV buffer on the receiving side. The effect that can be achieved.

Embodiment 7 FIG. In the fourth embodiment, M
When switching between PEG-2 bit streams, MPEG
FIG. 11 shows an example in which the encoding method of the −2 bit stream (2) is automatically determined, and the same encoding method as the encoding method is designated to generate the replacement bit stream (4). As shown, when an encoding method of the replacement bit stream (4) is given from the outside, the replacement bit stream (4) is generated in accordance with the encoding method, and the replacement of the MPEG-2 bit stream (2) is performed. The process of determining the encoding method may be omitted.

Next, the operation will be described. Hereinafter, a frame coded by an inter-frame predictive coding method for coding difference data from a frame located ahead of a current frame when rearranged in the display order is a P picture,
A frame coded by an inter-frame predictive coding method for coding differential data from a frame located in front and behind is encoded by a B-picture, an intra-frame coding method using only information on a frame to be coded. The resulting frame is called an I picture.

As in the fourth embodiment, for example, from the first MPEG-2 bit stream (1) such as a program,
Second MPEG-2 bit stream such as CM (2)
The operation when switching to is described. As in the fourth embodiment, an operation for switching from an MPEG-2 bit stream (1) such as a program to an MPEG-2 bit stream (2) such as a CM will be described. The rough operation is the same as that of the fourth embodiment,
In the seventh embodiment, the control unit 28 does not acquire the information on the encoding method of the MPEG-2 bit streams (1) and (2) detected by the frame information detection units 23 and 25.

Further, the control unit 28 instructs the replacement coded data generation unit 27 of the coding system input from the outside through the coding system input unit 32. The replacement coded data generation unit 27 generates the replacement bit stream (4) according to the specified coding method, and the stream generated at this time is the same stream as in the fourth embodiment. Hereinafter, the switching of the bit stream is performed in the same manner as the operation of the fourth embodiment.

With the above-described configuration, in the encoded image signal transmission system, if information on the encoding method and the decoding start timing of the encoded image signal such as the number of pixels of a frame and the frame rate is known, By instructing the encoding method of the replacement bit stream (4) from the outside, the control unit 28 does not need to detect the encoding method of the MPEG-2 bit stream such as the number of pixels of the frame and the frame rate. , VBV_DEL
The same effect as in the fourth embodiment can be obtained without providing a decoding time information detecting unit for detecting information such as AY, PTS, and DTS.

Embodiment 8 FIG. FIG. 12 is a configuration diagram showing an encoded image signal transmission system according to Embodiment 8 of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will be omitted. Reference numeral 51 denotes a coded image signal storage device that stores coded image signals. In the eighth embodiment, the switching unit 30 forms an output unit.

In the first to seventh embodiments,
Although the coded image signal transmission system that selects and outputs one from a plurality of coded image signal bit streams has been described, the coded image signal bit stream stored in the coded image signal A coded image signal transmission system that reproduces and transmits the coded image signal will be described.

FIG. 13 is an explanatory diagram showing an example of the configuration of a bit stream by the encoded image signal transmission system. In the figure, (2) is a bit stream of the encoded image signal stored in the encoded image signal storage device 51.
In the bit stream of (2), as an encoding method for each frame, an intra-frame encoding method for encoding using only image data of the encoding target frame and a display order for the encoding target frame are rearranged. A case is shown in which a moving image is encoded by a moving image encoding method that employs inter-frame predictive encoding in which difference data from a reference frame positioned at the front and / or the rear is sometimes encoded.

Further, the frame of _219B in the bit stream of (2) is a frame coded by the inter-frame predictive coding system located at the 19th position in the display order. Further, the arrows described by the solid lines indicate the reference relationship at the time of encoding each frame. For example, the 2 _19B frame in the bit stream shown in (2) is 2
₁₈ with reference to each frame of _I, 2 _21P shows that encoded.

(3) is a bit stream of the coded image signal stored in the coded image signal storage device 51 (2)
Is a bit stream obtained by simply reproducing from the reproduction start point (A). In the bit stream of (3), 2 _16B and 2 _17B frames in the bit stream after the reproduction start point (A) are referred to at the time of encoding.
_Since there is no _15P frame, an error occurs when decoding is performed by the decoder, and noise is generated by obtaining an unexpected decoded image.

(4) is a bit stream that is output by replacing a part of the original bit stream at the start of reproduction of the bit stream (2) stored in the coded image signal storage device 51. Here, the replacement bit stream (4) is obtained by referring to the frame in the bit stream before the reproduction start point in the bit stream (2) of the coded image signal output immediately after the start of the reproduction. This is a bit stream for replacing a bit stream of one or more frames that have been predictively encoded.

Therefore, the replacement bit stream (4)
Is a bit stream corresponding to a frame coded according to the same coding method as the bit stream (2) of the coded image signal. When each frame is coded, it is rearranged in the display order with respect to the frame to be coded. This is a bit stream that is coded with reference to only the intra-coded frame that is positioned forward in the bit stream and positioned after the frame to be coded in the bit stream. In order to prevent the occurrence of an error when decoding the bit stream by the image decoding device 31, information on the frame decoding start timing and the display time is replaced with the replacement bit stream (4) of the bit stream (2) before the replacement. Generate as a stream that matches the frame.

The bit stream of the coded image signal stored in the coded image signal storage device 51 is represented by (A)
In the bit stream (5) outputted when the reproduction is started from the point (2), the 2 _16B and 2 _17B frames in the bit stream after the reproduction start point (A) are replaced with the 3 _1B and 3 _2B frames. As a result, there is no frame that refers to the _215P frame included in the bit stream before (A), so that noise does not occur during decoding.

Next, the operation will be described. Hereinafter, for example, an operation in the case where a bit stream (2) of a coded image signal of a stored program or the like is reproduced from the middle will be described. First, a bit stream (2) of a coded image such as a program input from an external coded image signal storage device 51 is input to a frame information detection unit 25 and a decoding time information detection unit 26.

The frame information detecting section 25 detects a frame boundary from the input bit stream (2), detects the position of the frame coded by the intra-frame coding method, and notifies the control section 28 of the frame position. I do. The decoding time information detection unit 26 detects a parameter that affects the decoding timing at the time of decoding from the bit stream (2), and notifies the control unit 28 of the parameter.

In the control unit 28, the bit stream (2)
Of the encoding method such as the number of pixels of the frame and the frame rate in the above, and generates the replacement bit stream (4) in the same manner as the bit stream (2). Instruct the unit 27. The replacement coded data generation unit 27 generates a replacement bit stream (4) according to the specified coding method. The stream generated at this time is located when the encoding target frame is rearranged in the display order, and encodes difference data from a frame located behind the encoding target frame in the bit stream. It is. In addition, the bit stream is one or a plurality of bit streams encoded by an inter-frame difference prediction encoding method in which the difference data from the referenced frame is set to zero so that the data length becomes the shortest.

Note that the control unit 28 instructs the replacement coded data generation unit 27 in advance with parameters that affect the decoding start timing of the bit stream (2) acquired from the decoding time information detection unit 26, so that the A parameter affecting the decoding start timing of the replacement bit stream (4) is generated as a stream equal to the bit stream (2).

Further, when a part or all of the bit stream of the coded image signal stored in the coded image signal storage device 51 is rearranged in the display order with respect to the frame to be coded, forward and / or When a bit stream is encoded by a moving picture encoding method employing inter-frame predictive encoding for encoding difference data from a frame located below (hereinafter referred to as a reference frame), the stream is encoded in arbitrary frames. If the encoded image signal is reproduced from the middle, decoding may not be performed correctly because the frame referred to by the frame to be decoded does not exist in the bit stream after the reproduction start point. Therefore, the control unit 28 sends the bit stream (2) to the switching unit 30 in units of the timing immediately before the frame encoded by the intra-frame encoding method in the bit stream (2) detected by the frame information detection unit 25. Instruct the selection of 2).

When reproducing the coded image signal, the control unit 28 determines whether the bit stream (2) after the reproduction start point has the reproduction start point and the bit stream after the reproduction start point when rearranged in the display order. Switching the selection of the replacement bit stream (4) in place of the bit stream of all the inter-frame difference prediction coded frames existing in the bit stream between the first coded frame and the intra-coded frame Instruct the unit 30.

FIG. 14 is a flowchart showing a bit stream replacement process performed by the control unit 28 after the reproduction start point. In the figure, every time the frame information detection unit 25 detects a frame boundary from within a bit stream, the control unit 28 rearranges the position in the bit stream from the reproduction start point in units of frames and the display order. Hour position,
And the encoding method are stored in the storage unit 29 for each frame.

The control unit 28, based on the frame position from the reproduction start point stored in the storage unit 29, reorders the reproduction start point and the display order in the order of display. When the inter-frame prediction difference coded frame positioned in the bit stream is detected between the frame and the converted frame, the switching unit 30 selects the replacement bit stream (4) to replace the bit stream. Instruct.

By the above operation, the bit stream output from the coded image signal transmission system includes frames included in the bit stream before the reproduction start point in the bit stream after the reproduction start point. Reference frames can be eliminated.

With the above configuration, the bit stream output from the coded image signal transmission system includes frames included in the bit stream before the reproduction start point in the bit stream after the reproduction start point. Since there is no frame to refer to, even if the stream of the accumulated coded image signal is reproduced from the middle, an error at the time of decoding due to the absence of a frame to be referred to at the time of decoding,
It is possible to suppress generation of noise. Further, since the replacement bit stream (4) is a frame having a difference of zero from the intra-coded frame of the coded image signal to be reproduced, the frame immediately after the start of reproduction is a still image during decoding for one or more frames. It will be displayed, and no specific frame specific to the device will be displayed. Also, since the bit stream of the frame that does not exist in the original input bit stream is not inserted,
The insertion of unnecessary frames does not extend the program time.

Embodiment 9 FIG. In the eighth embodiment, the bit stream (2) after the reproduction start point is partially replaced with the replacement bit stream (4) and output. However, the bit stream (2) after the reproduction start point is output. Only when the frame No. refers to a frame of the bit stream before the reproduction start point, the bit stream related to the frame may be replaced with the replacement bit stream (4) and output.

Next, the operation will be described. Hereinafter, a case will be described in which a bit stream (2) of a coded image signal such as a stored program is reproduced from the middle.
The general operation is the same as that of the eighth embodiment, but the bit stream replacement process is the operation described in FIG. In FIG. 15, each time the frame information detection unit 25 detects a frame boundary from within the bit stream, the control unit 28 rearranges the position in the bit stream from the reproduction start point in units of frames and the display order. The position and the encoding method at the time of performing are stored in the storage unit 29 for each frame.

The control unit 28, based on the frame position from the reproduction start point stored in the storage unit 29, reorders the reproduction start point and the display order in the order of display, and the code in the frame located first after the reproduction start point. When a frame positioned in the bit stream is detected between the frame and the encoded frame, the position of the frame referred to at the time of encoding is determined from the reproduction start point based on the encoding information of the frame acquired from the frame information detection unit 25. Is also determined to be a previous frame. At this time, when determining that the control unit 28 refers to a frame before the reproduction start point, the control unit 28 instructs the switching unit 30 to select the replacement bit stream (4) to replace the bit stream. However, when it is determined that the frame before the reproduction start point is not referred to, the switching unit 30 is instructed to select the bit stream (2) so as not to perform the replacement.

With the above-described structure, the effects of the eighth embodiment can be obtained, and each frame of the bit stream of the coded image signal after the start of the reproduction is encoded without referring to the frame before the reproduction start point. If the bit stream is not replaced, the frame immediately after the reproduction start point is displayed as a still image for one or more frames during decoding when the stored bit stream is reproduced from the middle. The effect of preventing this is obtained.

Embodiment 10 FIG. In Embodiment 8 described above,
When the bit stream (2) of the coded image signal stored in the coded image signal storage device 51 is reproduced from the middle, the coding method of the bit stream (2) is automatically determined and the same as the coding method is determined. Has been described in which the coding method of the replacement bit stream (4) is generated by instructing the coding method of the replacement bit stream (4), as shown in FIG. , A replacement bit stream according to the encoding method (4)
May be generated, and the process of determining the encoding method of the bit stream (2) may be omitted.

Next, the operation will be described. As in the case of the eighth embodiment, the operation in the case where the bit stream (2) of an encoded image signal such as a stored program is reproduced from the middle will be described. The rough operation is the same as that of the eighth embodiment. The bit stream (2) stored in the coded image signal storage device 51 is input to the frame information detecting unit 25 and the decoding time information detecting unit 26.

The frame information detecting section 25 detects a frame boundary from the bit stream (2), detects the position of the frame coded by the intra-frame coding method, and notifies the control section 28 of the detected position. The control unit 28 obtains the coding method of the replacement bit stream (4) from the outside by the coding method input unit 32, and determines whether to generate the replacement bit stream (4) having the same method as the coding method. It instructs the substitute encoded data generation unit 27.

The replacement coded data generator 27 replaces the replacement bit stream (4) in accordance with the specified coding method.
Generate The stream generated at this time is positioned forward when rearranged in the display order with respect to the encoding target frame, and encodes difference data from a frame located behind the encoding target frame in the bit stream. Is what you do. In addition, the bit stream is one or a plurality of bit streams encoded by an inter-frame difference prediction encoding method in which the difference data from the referenced frame is set to zero so that the data length becomes the shortest.

The control unit 28 instructs the replacement coded data generation unit 27 in advance with parameters that affect the decoding start timing of the bit stream (2) acquired from the decoding time information detection unit 26, thereby obtaining the difference. A parameter affecting the decoding start timing of the replacement bit stream (4) is generated as a stream equal to the bit stream (2).

Thereafter, the bit stream of the coded image signal output from the coded image signal transmission system is reproduced by reproducing the stored bit stream of the coded image signal from the middle by the same operation as in the eighth embodiment. In the bit stream after the point, it is possible to eliminate a frame that refers to a frame included in the bit stream before the reproduction start point.

With the above-described configuration, in the encoded image signal transmission system, information on the encoding method such as the number of pixels of the frame and the frame rate and the decoding start timing of the accumulated encoded image signal are known. In some cases, an external replacement bit stream (4)
The control unit 28 does not need to detect the coding system of the input coded image signal, such as the number of pixels of the frame and the frame rate, and provides information on the decoding start timing and the display time. Embodiment 8 without providing a decoding time information detecting unit for detecting
The same effect as described above can be obtained.

Embodiment 11 FIG. In the eleventh embodiment, in the coded image signal transmission system according to the eighth embodiment, the coded image signal stored in the coded image signal storage device 51 is encoded according to the MPEG-standard defined by ISO / IEC 13818-2. A case will be described where the image signal is coded according to the two methods and is a coded image signal having a GOP structure. FIG. 17 is a configuration diagram showing an encoded image signal transmission system according to Embodiment 11 of the present invention.
In the figure, the same reference numerals as those in FIGS.

Next, the operation will be described. Hereinafter, a frame coded by an inter-frame predictive coding method for coding difference data from a frame located ahead of a current frame when rearranged in the display order is a P picture,
A frame coded by an inter-frame predictive coding method for coding differential data from a frame located in front and behind is encoded by a B-picture, an intra-frame coding method using only information on a frame to be coded. The resulting frame is called an I picture. As in the eighth embodiment, for example, MPEG-2
The operation in the case where the bit stream (2) is reproduced from the middle and transmitted is described.

In FIG. 17, the MPEG-2 bit stream (2) stored in the coded image signal storage device 51 includes a frame information detecting section 25, a GOP information detecting section 4
4 and the decoding time information detection unit 26. The frame information detection unit 25 detects a frame boundary from the MPEG-2 bit stream (2), detects a picture header of each frame, and notifies the control unit 28. The GOP information detection unit 44 detects a GOP boundary position in the bit stream (2) and
Notify. The decoding time information detecting unit 26 outputs the MPEG-2
From the bit stream (2), VBV_DELAY,
Each parameter of PTS and DTS is detected and notified to the control unit 28.

The control unit 28 analyzes a GOP header, a sequence header, a picture header, and the like in the MPEG-2 bit stream (2), and substitutes replacement bits of the same encoding method as the MPEG-2 bit stream (2). The generation of the stream (4) is performed by the replacement encoded data generation unit 2
Instruct 7. The replacement coded data generation unit 27 generates a replacement bit stream (4) according to the instructed method. The stream generated at this time is located ahead when rearranging the encoding target frame in the display order,
And in the bit stream, only the frame coded by the intra-frame coding method located behind the frame to be coded is used as a reference frame of each macroblock,
In addition, the bit stream is a bit stream of one or a plurality of frames encoded by an inter-frame difference prediction encoding method in which a difference from the reference frame is set to zero so that the data length becomes shortest.

Note that the control unit 28 controls the MPEG-2 bit stream (2) acquired from the decoding time information detection unit 26.
VBV_DELAY, PTS, and DTS parameters of the replacement bit stream (4) are instructed in advance to the replacement coded data generation unit 27.
Each parameter of AY, PTS, and DTS is generated as a stream equal to the MPEG-2 bit stream (2).

Further, the control unit 28 controls the GOP information detection unit 4
MPEG2 bit stream detected by 4 (2)
By instructing the switching unit 30 to select the MPEG-2 bit stream (2) at a timing in units of GOP boundaries in, output of the MPEG-2 bit stream (2) is started.

At this time, when reproducing the above-mentioned bit stream, the control unit 28 performs the reproduction from the reproduction start point of the MPEG-2 bit stream (2) after the reproduction start point.
The bit streams of all the B pictures existing in the bit stream up to the frame of the I picture located first when rearranged in the display order are replaced with replacement bits generated by the replacement coded data generation unit 27. The switching unit 30 is instructed to switch to the stream (4).

FIG. 18 is a flowchart showing a bit stream replacement process by the control unit 28 after the reproduction start point. In the figure, the control unit 28 controls M after the reproduction start point.
For the PEG-2 bit stream (2), all the B pictures existing in the bit stream between the playback start point and the I picture frame located first in the display order from the playback start point are replaced with replacement bits. Stream (4)
In order to replace, the switching unit 30 is instructed to select the replacement bit stream (4).

With the above operation, the coded image signal transmission system can perform the above operation even when the coded image signal having the GOP structure coded by the MPEG-2 system specified by ISO / IEC 13818-2 is input. The same effect as in the eighth embodiment can be obtained.

In the eleventh embodiment, the MPEG-2 bit stream after the reproduction start point has an MPEG GOP structure only when the frame has an open GOP structure encoded with reference to the frame in the preceding GOP. -2
The replacement bit stream (4), which is data, may be replaced. This has the effect of preventing the frame immediately after the start of reproduction from being displayed as a still image for one or more frames.

Embodiment 12 FIG. In the first embodiment,
The case where the bit stream to be input to the coded image signal transmission system is synchronized with the timing at which the bit stream can be switched between the input bit streams has been described. The same effect can be obtained even when the switchable timing of the bit stream is shifted.

In FIG. 19, reference numerals 61, 62 and 63 are buffers for temporarily storing bit streams. The control unit 28 switches the bit streams (1) and (2) to be switched and further the replacement bit stream (4) by adjusting the read timing from the buffer and aligning the switchable positions of the bit streams. Accordingly, the same effect as in the first embodiment can be obtained. Further, the buffers 61, 62, and 63 are not limited to the first embodiment, and the same effects can be obtained when applied to the second to eleventh embodiments.

In the first to twelfth embodiments, when the replacement bit stream (4) is rearranged in the display order with respect to each frame, the difference from the rear frame is zero. Although it is generated, the difference does not necessarily have to be zero, and the data length after generation is
If the data length is shorter than or equal to the data length of the frame of the bit stream (2) to be switched,
An equivalent effect can be obtained. In Embodiments 1 to 11, the case where the number of encoded image signals input to the encoded image signal transmission system is 2 has been described.
The same applies to the case where the number of input coded image signals exceeds two.

In the sixth embodiment and the like, if the data length of the replacement bit stream (4) is shorter than the bit stream (2) to be switched, null data is added to the replacement bit stream (4). Although insertion is shown (see FIGS. 9 and 20), a replacement bit stream (4) having a size equal to the data length of the bit stream (2) to be switched may be generated. The effect can be achieved.

Further, in the above-described first embodiment and the like, the case where the coded replacement data generating unit 27 generates the replacement bit stream (4) every time switching is performed is described. The replacement bit stream (4) may be held.

Further, in the above-described first embodiment and the like, the case where the replacement encoded data generation unit 27 generates the replacement bit stream (4) every time switching is performed is described.
The same effect can be obtained by inputting a replacement bit stream (4) encoded by an external image encoding device.

[0130]

As described above, according to the present invention, when the control means instructs the switching of the bit stream, the encoding method of the bit stream of the switching candidate is detected and the same encoding method as the encoding method is detected. The replacement bit stream is generated, and a part of the bit stream after the switching point is replaced with the replacement bit stream so that the replacement bit stream is output. There is an effect that it is possible to prevent generation of noise due to signal switching.

According to the present invention, only when a frame of a bit stream after the switching point refers to a frame of a bit stream before the switching point, the bit stream related to the frame is replaced with the replacement bit stream. So that when the frame of the bit frame before the switching point is not referred to,
The bit stream related to the frame is not replaced with the replacement bit stream. Therefore, even if the bit stream is switched, there is an effect that the frame immediately after the switching during decoding can be prevented from being displayed as a still image for one or more frames.

According to the present invention, when the coding scheme of the bit stream of the switching candidate is given from the outside, the detection processing of the coding scheme of the bit stream is stopped, so that the processing is simplified. There is an effect that can be.

According to the present invention, when handling an image signal having a group of picture structure encoded by the MPEG-2 system, a boundary between the group of pictures is detected, and switching of a bit stream is instructed at the boundary. With this configuration, even when an image signal having a GOP structure encoded by the MPEG-2 method is input, generation of noise due to switching of the image signal can be performed without changing the program time or displaying a black screen. There is an effect that can be prevented.

According to the present invention, only when the frame of the bit stream of the image signal has the open group of picture structure encoded with reference to the frame in the preceding group of pictures, the MPEG-2 data Since the replacement of the replacement bit stream is performed, if the frame of the bit frame before the switching point is not referred to, the replacement of the bit stream related to the frame is performed. There is no. Therefore, even if the bit stream is switched, there is an effect that the frame immediately after the switching during decoding can be prevented from being displayed as a still image for one or more frames.

According to the present invention, when the frame data length of the bit stream before replacement is longer than the frame data length of the replacement bit stream, a bit stream representing null information is added to the replacement bit stream. Since the frame data lengths before and after the replacement are configured to be equal, there is an effect that the bit stream can be switched without causing a failure such as overflow or underflow of the VBV buffer on the receiving side.

According to the present invention, MPEG-2
Since the configuration is such that the encoding method of the replacement bit stream as data is input and the replacement bit stream is generated, there is an effect that the processing can be simplified.

According to the present invention, when the control means reproduces the bit stream of the image signal from the middle, the control section detects the coding scheme of the bit stream and replaces the replacement bit stream of the same coding scheme with the coding scheme. Since it is configured to generate and replace a part of the bit stream after the playback start point with a replacement bit stream and output it, it is possible to change the program time and display the image signal halfway without displaying a black screen. There is an effect that generation of accompanying noise can be prevented.

According to the present invention, only when the frame of the bit stream after the reproduction start point refers to the frame of the bit stream before the reproduction start point, the bit stream of the frame is replaced with the replacement bit stream. Therefore, when the frame of the bit stream before the reproduction start point is not referred to, the bit stream related to the frame is not replaced with the replacement bit stream. Therefore, even when the bit stream is reproduced halfway, there is an effect that the frame immediately after the start of the reproduction at the time of decoding can be prevented from being displayed as a still image for one or more frames.

According to the present invention, when the coding system of the bit stream of the image signal is externally provided, the detection process of the coding system of the bit stream is stopped, so that the processing is simplified. There is an effect that can be.

According to the present invention, when handling an image signal having a group of picture structure encoded by the MPEG-2 system, a boundary of the group of pictures is detected, and an output of a bit stream is instructed at the boundary. With such a configuration, even when an image signal having a GOP structure encoded by the MPEG-2 system is input, the noise caused by the midway reproduction of the image signal can be reduced without changing the program time or displaying a black screen. There is an effect that generation can be prevented.

According to the present invention, only when the frame of the bit stream of the image signal has the open group of picture structure encoded with reference to the frame in the preceding group of pictures, the MPEG-2 data Since the replacement bit stream is configured to be replaced, when the frame of the bit stream before the reproduction start point is not referred to, the bit stream related to the frame is replaced with the replacement bit stream. Never. Therefore, even when the bit stream is reproduced halfway, there is an effect that the frame immediately after the start of the reproduction at the time of decoding can be prevented from being displayed as a still image for one or more frames.

According to the present invention, when the frame data length of the bit stream before replacement is longer than the frame data length of the replacement bit stream, a bit stream representing null information is added to the replacement bit stream. Since the frame data lengths before and after the replacement are configured to be equal, there is an effect that the bit stream can be switched without causing a failure such as overflow or underflow of the VBV buffer on the receiving side.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an encoded image signal transmission system according to Embodiment 1 of the present invention.

FIG. 2 is an explanatory diagram showing a configuration example of a bit stream by an encoded image signal transmission system.

FIG. 3 is a flowchart illustrating a bit stream replacement process performed by a control unit after a switching point.

FIG. 4 is a flowchart showing a bit stream replacement process performed by a control unit after a switching point.

FIG. 5 is a configuration diagram illustrating an encoded image signal transmission system according to a third embodiment of the present invention.

FIG. 6 is a configuration diagram showing an encoded image signal transmission system according to Embodiment 4 of the present invention.

FIG. 7 is a flowchart showing a bit stream replacement process performed by the control unit after the switching point.

FIG. 8 is a flowchart showing a bit stream replacement process performed by the control unit after the switching point.

FIG. 9 is a configuration diagram showing an encoded image signal transmission system according to Embodiment 6 of the present invention.

FIG. 10 is a flowchart showing a bit stream replacement process performed by the control unit after the switching point.

FIG. 11 is a configuration diagram showing an encoded image signal transmission system according to Embodiment 7 of the present invention.

FIG. 12 is a configuration diagram showing an encoded image signal transmission system according to Embodiment 8 of the present invention.

FIG. 13 is an explanatory diagram illustrating a configuration example of a bit stream by the encoded image signal transmission system.

FIG. 14 is a flowchart showing a bit stream replacement process performed by the control unit after the reproduction start point.

FIG. 15 is a flowchart showing a bit stream replacement process performed by the control unit after the reproduction start point.

FIG. 16 is a configuration diagram showing an encoded image signal transmission system according to Embodiment 10 of the present invention.

FIG. 17 is a configuration diagram showing an encoded image signal transmission system according to Embodiment 11 of the present invention.

FIG. 18 is a flowchart showing a bit stream replacement process performed by the control unit after the reproduction start point.

FIG. 19 is a configuration diagram showing an encoded image signal transmission system according to Embodiment 12 of the present invention.

FIG. 20 is a configuration diagram showing an encoded image signal transmission system according to Embodiment 12 of the present invention.

FIG. 21 is a configuration diagram showing a conventional encoded image signal transmission system.

[Explanation of symbols]

21 image encoding device, 22 image encoding device, 23
Frame information detecting section (control means), 24 decoding time information detecting section (control means), 25 frame information detecting section (control means), 26 decoding time information detecting section (control means), 27
Replacement encoded data generation unit (control unit), 28 control unit (control unit), 29 storage unit (control unit), 30 switching unit (selection unit, output unit), 31 image decoding device, 3
2 Coding method input unit (control means), 41 MPEG-
2 encoder, 42 MPEG-2 encoder, 43
GOP information detecting section (control section), 44 GOP information detecting section (control section), 45 MPEG-2 decoder, 46 frame size detecting section (control section), 47 frame size detecting section (control section), 48 frame size detecting section (Control unit), 49 null data generation unit (control unit), 50 switching unit (control unit), 51 coded image signal storage device, 61 buffer, 62 buffer, 63 buffer.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Susumu Oka 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation F-term (reference) 5C023 AA21 AA27 AA28 BA01 BA17 CA03 CA08 DA04 EA02 5C059 KK01 MA00 MA05 PP04 RC01 RC09 RE02 SS02 TA17 TB00 TB03 TC27 TD18 UA02 UA05 UA38

Claims (13)

[Claims] 1. An encoded image comprising: a selection unit that selects and outputs an arbitrary bit stream from a plurality of bit streams of image signals; and a control unit that instructs the selection unit to select a bit stream to be selected. In the signal transmission system, when instructing to switch the bit stream, the control unit detects an encoding method of the bit stream of the switching candidate, generates a replacement bit stream having the same method as the encoding method, and performs switching. An encoded image signal transmission system, wherein a part of a bit stream after a point is replaced with a replacement bit stream and output. 2. The control unit according to claim 1, wherein the control unit replaces the bit stream of the bit stream with the replacement bit stream only when the frame of the bit stream after the switching point refers to the frame of the bit stream before the switching point. 2. The encoded image signal transmission system according to claim 1, wherein the encoded image signal is transmitted. 3. The control unit according to claim 1, wherein when a coding scheme of a bit stream as a switching candidate is given from the outside, the control unit stops detection processing of the coding scheme of the bit stream. Coded image signal transmission system. 4. When handling an image signal having a group of picture structure encoded by the MPEG-2 system, the control means detects a boundary of the group of pictures and instructs to switch a bit stream at the boundary. The encoded image signal transmission system according to any one of claims 1 to 3, wherein: 5. The control unit according to claim 1, wherein the frame of the bit stream of the image signal has an open group of picture structure encoded with reference to a frame in the preceding group of pictures. The coded image signal transmission system according to claim 4, wherein the replacement bit stream is replaced. 6. When the frame data length of the bit stream before replacement is longer than the frame data length of the replacement bit stream, the control means adds a bit stream representing null information to the replacement bit stream. 6. The coded image signal transmission system according to claim 4, wherein frame data lengths before and after replacement are equalized. 7. The control unit according to claim 4, wherein the control unit inputs an encoding method of a replacement bit stream which is MPEG-2 data from outside and generates the replacement bit stream. Item 7. An encoded image signal transmission system according to any one of Items 6. 8. An encoded image signal transmission system comprising: output means for outputting a bit stream of a stored image signal; and control means for controlling output of the bit stream by the output means. When a bit stream of an image signal is reproduced from the middle, an encoding method of the bit stream is detected, a replacement bit stream of the same method as the encoding method is generated, and one of the bit streams after the reproduction start point is extracted. A coded image signal transmission system characterized in that a part is replaced with a replacement bit stream and output. 9. The control unit according to claim 6, wherein the bit stream of the bit stream after the reproduction start point refers to a frame of the bit stream before the reproduction start point. The encoded image signal transmission system according to claim 8, wherein the encoded image signal is transmitted after being output. 10. The control unit according to claim 8, wherein the control unit stops the detection process of the bit stream encoding system when the encoding system of the bit stream of the image signal is given from outside. Coded image signal transmission system. 11. When handling an image signal having a group of picture structure encoded by the MPEG-2 system, the control unit detects a boundary of the group of pictures and instructs output of a bit stream at the boundary. The encoded image signal transmission system according to any one of claims 8 to 10, wherein: 12. The control unit according to claim 1, wherein the frame of the bit stream of the image signal has an open group of picture structure encoded with reference to a frame in the preceding group of pictures. 12. The system according to claim 11, wherein the replacement bit stream is replaced. 13. When the frame data length of the bit stream before replacement is longer than the frame data length of the replacement bit stream, the control means adds a bit stream representing null information to the replacement bit stream. 13. The coded image signal transmission system according to claim 11, wherein frame data lengths before and after replacement are equalized.