JP3517463B2 - Playback device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproducing apparatus such as a digital VTR for recording / reproducing digital television broadcast signals.

[0002]

2. Description of the Related Art In recent years, digital processing of images has been studied. In particular, for high efficiency encoding for compressing image data, various systems have been proposed for standardization, and in the United States, ATV (Advanced Television) which is a next-generation television broadcasting system using the MPEG-2 system has been proposed. Methods are being considered.

FIG. 5 is an explanatory diagram for explaining the MPEG encoding system. In the figure, the arrow indicates the direction of prediction in encoding. FIG. 6 is an explanatory diagram showing the order of image data by the encoding process, the arrangement on the recording medium, the decoding process, and the reproduced image process in the MPEG encoding system.

In FIG. 5, the MPEG encoding system constitutes a GOP (Group of Picture) with a predetermined number of frame images. At least one intra-coded image I is included in the GOP
Sheets are included. The intra-image coded image I is one frame of image data coded by DCT (discrete cosine transform). From the intra-picture coded image I, one frame of image data at every predetermined a frames is converted into forward predictive coded images P ₁ and P ₂ . In this case, the forward predictive coded image P ₂ is converted from the forward predictive coded image P ₁ . Further, the image data of each frame between the intra-picture coded image I or the first forward predictive coded image P ₁ and the second forward predictive coded image P ₁ is the image data of the front and rear. It is converted into a bi-predictive coded image B by the bi-predictive coding used.

As shown in FIGS. 5 and 6, first, the intra-picture coded picture I is coded. The intra-picture coded picture I is coded only by the information in the frame and does not include prediction in the time direction. Next, a forward predictive encoded image P is created, and the intra-picture encoded image I or the forward predictive encoded image P is generated.
After that, the bidirectional predictive coded image B is coded. Forward predictive encoded image P and bidirectional predictive encoded image B
Uses the correlation with other image data. As described above, due to the prediction method of each image data, the bidirectionally predictive coded image B is recorded on the recording medium after the intra-picture coded image I or the forward predictive coded image P, and the original order at the time of decoding. Returned to.

Since the intra-picture coded picture I is coded only by the information in the frame, it can be decoded only by a single piece of coded data. On the other hand, the forward predictive coded image P and the bidirectional predictive coded image B are coded by utilizing the correlation with other image data, so that they cannot be decoded by only the single coded data. Has become.

In the MPEG encoding method, the recording rate is specified (standard 1.2 Mbps), but the data length is variable. Therefore, it is not possible to specify at which position the intra-picture coded image I included in the GOP is recorded, and it is not possible to specify the data length of one GOP. The above-mentioned MPEG encoding system is applied to a digital VTR.
In the normal reproduction, the coded images I, B, and P are sequentially reproduced, so that no particular problem occurs.

However, when special reproduction such as fast-forward reproduction for search is performed, the encoded images I, B and P are not sequentially reproduced. Further, when performing special reproduction, only a part of the recording track on the recording medium is reproduced, and the position of the intra-coded image I on the recording medium is not specified. Therefore, the intra-coded image I is always reproduced. Not always possible. In this case, the forward predictive coded image P and the bidirectional predictive coded image B cannot be reproduced. For this reason,
For example, in Japanese Patent Laid-Open No. 4-298802,
A technique has been disclosed in which coded image data is recorded at a predetermined position on a recording medium that can be reproduced during special reproduction, and the data is reproduced during special reproduction to reproduce a screen.

Next, in the MPEG-2 system, a coded image signal, audio signal, or other bit string is referred to as an elementary stream. A PES (Packetized Elementary Stream) packet is defined as a structure for carrying an elementary stream. This is PES after the PES header information.
It has a structure in which ES bay road continues. A set of elementary streams having a common time base in the MPEG-2 system is called a program.

Two formats are defined for encoding in the MPEG-2 system. One is the transport stream and the other is the program stream. The definitions of both the transport stream and the program stream include a necessary and sufficient grammar for synchronizing the decoding and reproduction of video and audio. Program stream has one or more PES with a common time base
It combines packets into a single bit string.

The transport stream is a single bit string formed by connecting one or more independent programs to each other. Each of the programs can have an independent time base. is there. Then, in the above-mentioned ATV system, the transport stream is used.

In the MPEG-2 decoding system, SCR (System
Clock Reference) and PCR (Program Clock Reference) in the case of a transport system are used for synchronization.

FIG. 7 is a block diagram showing an example of an SCR or PCR decoding circuit. In the figure, 1 is an input terminal, 2 is a subtractor, and 3 is an LPF (Low Pass Filter).
), 4 is an amplifier, 5 is a VCO (Voltage Controlled Os)
cillator), 6 is a counter, and 7 is an output terminal.

Next, the operation will be described. The output of the counter 6 is called STC (System Time Clock). When SCR or PCR arrives at the input terminal 1 of this decoding circuit, the subtracter 2 calculates a comparison value between the current STC output from the counter 6 and the arrived SCR or PCR. This comparison value is output by the LPF 3 and the amplifier 4 as a control signal for the VCO 5. VC
O5 outputs a clock signal. This clock signal is
The frequency changes depending on the value of the control signal.

The output signal of the VCO 5 is input from an output terminal 7 to an MPEG decoder (not shown) to be used as a system clock and also to a counter 6. The counter 6 counts the system clock and counts the S
Output TC. This STC is input to the subtractor 2,
It constitutes a feedback loop that constitutes a PLL (Phase Locked Loop). S input to the above PLL
The time interval of CR and PCR inputs is set within 700 milliseconds in the case of SCR and within 100 milliseconds in the case of PCR.

In the case of the above-mentioned ATV system, PCR is used to achieve synchronization in the same manner as the above decoding circuit. MPE
The G-2 transport stream divides data such as images and audio into fixed-length transmission units called transport packets, and transmits them as a bit stream. The PCR and PSI (ProgramS
Data such as various kinds of identifier information called "Pecific Information" are appropriately incorporated, and the decoder detects and reproduces this PSI and initializes the decoder, thereby enabling a normal decoder of the bit stream.

In addition, PSI (Program Associ
application table), PMT (ProgramMap Table), and other information for identifying PID (Packet ID) and the like, and a transport packet containing target data is identified using this information.

When the mode of the VTR is changed from special reproduction such as search to normal reproduction, the normal reproduction data and the special reproduction data are written on the recording medium as independent data in time series. Since PCR and PSI are different, it is necessary to initialize the PCR and PSI decoder for normal reproduction data. Further, since the PCR becomes discontinuous between the normal reproduction and the special reproduction, it is necessary to set the discontinuity indicator in the header of the packet to 1 to notify the decoder of the discontinuity of the PCR.

FIG. 8 shows a procedure for decoding a bit stream according to the ATV method. First, as shown in FIG. 8, a transport packet in which the PAT is recorded, that is, a transport packet in which the PID recorded in the transport header is Ox0000 is detected from the ATV bit stream, and the PID is Ox00.
00 from the payload of the transport packet to P
Take out the AT and program map PI from this PAT
Read D. The program map PID is the PID (elementary PID) of a transport packet containing the program to be decoded.
Is the PID of the transport packet in which is described.

Next, a transport packet having a PID that matches the program map PID is detected, and PM is detected from the payload of the detected transport packet.
T is taken out and the elementary PID which is the PID of the transport packet in which the desired program is recorded is read from this PMT. Further elementary PID
A transport packet having a PID matching with is detected, and a desired program is taken out from the payload of the transport packet having the PID matching with the elementary PID.

[0021]

In the above conventional example, when the mode transitions from special reproduction such as forward search to normal reproduction, the VTR changes the PSI of normal reproduction data as shown in Case 1 of the timing chart of FIG. ATV decoder time _{(T x = t 3 ~t 5} ) until the reproduction is a problem that it is impossible is normal decoding of the bitstream.

Further, since the time from the time when the mode is changed from the special reproduction such as the forward search to the normal reproduction to the reproduction of the first PSI is not constant, when the search is terminated and the normal reproduction mode is entered, There is a problem that the time (transition time) from the search screen to the normal reproduction screen is not constant due to the transition timing, and the image is disturbed or missing during this period.

Therefore, the object of the present invention is to obtain the Case shown in FIG.
As shown in FIG. 2, when the ATV-compatible digital moving image signal recording / reproducing apparatus makes a mode transition from special reproduction such as forward search to normal reproduction, a transition period (t _{0 to} t ₃ ) until normal reproduction is performed. Shortening and reducing the variation of this transition period.

[0024]

According to the present invention, special reproduction data including special reproduction control information for decoding data and normal reproduction control information for decoding data are provided. A reproducing apparatus for reproducing encoded data including the normal reproduction data and the special reproduction data from a recording medium in which the normal reproduction data including the data is recorded independently in time series, and in a special reproduction mode. Detection means for detecting the control information for normal reproduction from the reproduced encoded data, storage means for storing control information for normal reproduction detected by the detection means, and normal reproduction in the special reproduction mode. When the control information for playback is detected, updating means is provided for updating the contents of the storage means with the latest detected control information for normal playback.

According to the third aspect of the present invention, special reproduction data including special reproduction control information for decoding data, and normal reproduction data including normal reproduction control information for decoding data. A reproducing apparatus for reproducing encoded data including the normal reproduction data and the special reproduction data from a recording medium recorded independently in time series,
The detection means for detecting the control information for the normal reproduction from the encoded data reproduced in the special reproduction mode, and the storage means for storing the control information for the normal reproduction detected by the detection means are provided. The information corresponds to a plurality of programs included in the encoded data, and second detecting means for detecting that the control information for special reproduction has changed in the special reproduction mode and clearing the contents of the storage means. Is further provided.

In the invention of claim 7, special reproduction data including special reproduction control information for decoding data, and normal reproduction data including normal reproduction control information for decoding data. A reproducing apparatus for reproducing encoded data including the normal reproduction data and the special reproduction data from a recording medium recorded independently in time series,
The detection means for detecting the control information for the normal reproduction from the encoded data reproduced in the special reproduction mode, and the storage means for storing the control information for the normal reproduction detected by the detection means are provided. The information is PSI.

[0027]

According to the first aspect of the present invention, the control information for normal reproduction is detected in the special reproduction mode and stored, and the control information stored at the time of the mode transition is used to reproduce reproduction encoded data. The time that cannot be decoded in the decoder that decodes is shortened. Then, when the control information for normal reproduction is detected in the special reproduction mode, the malfunction of the decoder is prevented by updating the contents of the storage means with the latest detected control information for normal reproduction.

[0028]

According to the third aspect of the invention, the control information for normal reproduction is detected in the special reproduction mode, stored in advance, and the control information stored at the time of mode transition is used to reproduce reproduction encoded data. The time that cannot be decoded in the decoder that decodes is shortened. Then, by detecting that the control information for special reproduction has changed in the special reproduction mode and clearing the contents of the storage means, when the mode transitions from the special reproduction mode to the normal reproduction mode, incorrect control information is reproduced. It prevents the decoder from malfunctioning by preventing it from being inserted into the encoded data.

[0030]

1 is a block diagram showing a first embodiment of the present invention. In FIG. 1, 101 is an input terminal of a bit stream reproduced by a VTR or the like, 110 is an input terminal of a mode transition signal of the VTR or the like, and 102 is a switch 1 described later.
A PSI detection circuit for detecting PSI from the bit stream output from 04, 103 is an ID (digital V) included in the bit stream input from the input terminal 101.
The sync block ID of TR, etc.) is detected to determine whether the bit stream is for trick play data (TPD, special reproduction mode) such as search or normal reproduction data (NPD), and the TPD / NPD identification signal is determined. To output I
D detection circuit. A switch 104 switches the bit stream input from the input terminal 101 into two systems according to the identification signal output from the ID detection circuit 103 and outputs the bit stream.

Reference numeral 105 is a comparison circuit which compares the PSI of the latest TPD with the PSI of the immediately preceding TPD and outputs 1 (H level) when a change in PSI is detected. 106 is the PSI of the latest NPD. Memory for holding, 107
Is a switch for selecting the PSI of the bitstream and the PSI held in the memory 106 according to the mode transition signal from the input terminal 110, 108 is a buffer memory, and 109 is an output terminal of the ATV bitstream.

Next, the operation will be described. In FIG. 1, the ATV bit stream input from the input terminal 101 is an ID detection circuit 103, a buffer memory 108,
It is input to the switch 104. The ID detection circuit 103 represents I representing the attribute of the data in the input bit stream.
D (sync block ID of digital VTR, etc.) is detected, and 1 is output when the PID is TPD, and 0 (L level) otherwise is output as the control signal of the switch 104. The switch 104 is controlled by the ID detection circuit 103, and the output of the ID detection circuit 103 is 1 (TPD).
The bit stream is output from the input terminal 101 to the TPD side when it is 0 and to the NPD side when it is 0 (NPD).

The PSI detection circuit 102 has two detection circuits for TPD and NPD, and independently cuts out transport buckets containing PSI from the bit stream of TPD and NPD output from the switch 104, respectively.
The PSI of TPD is output to the comparison circuit 105, and the PSI of NPD is output to the memory 106.

The comparison circuit 105 determines the PSI of the previous TPD.
Is stored and the previous PSI and the current PSI are compared. If the current PSI is the same as the previous PSI, the stored contents are held and 0 is output to the clear terminal of the memory 106. If the PSI of this time is different from the PSI of the previous time, the stored contents are replaced with the PSI of this time, and 1 is output to the clear terminal of the memory 106 to clear the stored contents.

The memory 106 continues in the write mode until 1 is input from the input terminal 110, and its contents are updated by the PSI of the NPD input from the switch 104 regardless of the VTR playback mode.

Next, as shown in the timing chart of FIG. 2, the switch 107 switches to the T (transient) side when the mode transition signal input from the input terminal 110 becomes 1. At the same time, reading of the memory 106 is started and PSI is read. The read PSI is output from the output terminal 109 via the switch 107.
Playback is performed while the switch 107 is closed to the T side,
That is, the bit stream input from the input terminal 101 is invalid data during a mode transition transition period such as VTR, or data that cannot be decoded because PSI is not reproduced after the mode transition.

The switch 107 is always N when the input from the input terminal 110 is 0 (modes other than special reproduction).
It is closed on the (normal) side, and at this time the input terminal 101
The bit stream input from the buffer memory 10
It is output from the output terminal 109 via 8 only.

FIG. 3 is a block diagram showing a second embodiment of the present invention. The parts corresponding to those in FIG. 1 are designated by the same reference numerals and the description of the structure and operation is omitted. In FIG. 3, 111
Is a memory controller for controlling and supplying the R / w and R / W address of the memory 106, and 112 is a logic circuit in which a Not circuit is connected to one input of a two-input AND circuit.

Next, the operation will be described. Memory 106
All operations are controlled by the memory controller 111. The memory controller 111 receives the PSI detection signal (A) from the PSI detection circuit 102 and the input terminal 110.
From the mode transition signal (B) from (1), the mode control signal (D) for writing (W) and reading (R) as shown in Table 1.
And the address (C) corresponding to the write and read modes are output.

[0040]

[Table 1]

The switch 107 is a logical product of the logical product of the negation of the PSI detection signal (A) output from the PSI detection circuit 102 in 112 and the mode transition signal (B) input from the mode transition signal input terminal 110. Controlled by. As shown in Table 1, the PSI detection signal output from the PSI detection circuit 102 is 0 (PSI not detected),
Under the condition that the mode transition signal from 110 is 1 (transition state of mode transition of VTR etc.), the switch 107 is switched to the T side, at the same time, reading of the memory 106 is started, and the output terminal 109 via the switch 107 Is output from.

During the period when the switch 107 is closed to the T side, that is, the bit stream input from the input terminal 101 is invalid data during the mode transition transient period such as VTR, or PSI is not reproduced after the mode transition. This is data that cannot be decoded.

FIG. 4 is a timing chart showing the operation of the present invention and the prior art. Case 1 shows the conventional operation and Case 2 shows the present invention. In Case 1, when there is a change request from special reproduction (FF search in this case) to normal reproduction at time t ₀ , the ATV decoder makes the first P for NPD at time t _4.
The SI is detected, and based on this, the ATV decoder starts decoding from the time point t _{5 and} an image for normal reproduction is obtained.
That is, the time required for mode transition is the period from t ₀ to t ₅ . Further, since the time point t ₄ at which PSI is detected may be different, the above period is not constant.

On the other hand, in the case of Case 2, t₀
If there is a mode change request at this point, t ₁By then
Read the PSI for NPD that was detected and stored
As it is embedded in the bitstream, the ATV decoder has t
₂Get PSI at time t,₃Start decoding from that point
An image for normal reproduction can be obtained.

Therefore, Case 1 can shorten the period in which the image is disturbed or missing for a period of T _x more than Case 2, and the period of t ₀ to t ₃ can be made substantially constant.

According to the embodiment of the present invention, the transport packet including the PSI of the normal reproduction data is cut out from the reproduced bit stream, and the cut out PS is cut out.
I is stored in the memory, and the contents of the memory are constantly updated by the PSI of the normal reproduction data reproduced during the normal reproduction and the special reproduction. The PSI stored in the memory is incorporated into the bit stream as a temporary PSI during the transition period until the PSI recorded on the recording medium is reproduced, and the PSI is output.

By doing so, it is possible to shorten the transition period of the mode transition by converting the bit stream that cannot be decoded until the PSI is reproduced by the normal reproduction into a decodable stream.

If the program ID (PID) of the normal reproduction data is changed to a program having a program ID different from that at the start of the forward search during the forward search, P
By configuring so that the contents of the memory are cleared when a change in ID is detected, improper PSI incorporation into the bit stream, that is, malfunction of the ATV decoder, is prevented when the mode transitions from forward search to normal playback. can do.

[0049]

As described above, according to the invention of claim 1, the control information for normal reproduction is detected in the special reproduction mode and stored, and the control information stored at the time of the mode transition is stored. By being configured to be used, there is an effect that it is possible to shorten the undecodable time in the decoder that decodes the reproduction coded data and reduce the disorder and the loss of the reproduced image. Then, when the normal reproduction control information is detected in the special reproduction mode, the contents of the storage means are updated with the latest detected normal reproduction control information to prevent the malfunction of the decoder. There is an effect that can be.

[0050]

According to the third aspect of the present invention, the control information for normal reproduction is detected in the special reproduction mode and stored, and the control information stored at the time of mode transition is used. This has the effect of shortening the undecodable time in the decoder that decodes the encoded data, and reducing the disorder and loss of the reproduced image. When the special reproduction mode control information is changed and the contents of the storage means are cleared, it is erroneous when the mode is changed from the special reproduction mode to the normal reproduction mode. It is possible to prevent the control information from being inserted into the reproduction coded data and prevent the malfunction of the decoder.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a timing chart showing the relationship between the reading of the stored PSI and the ATV bitstream in the first embodiment.

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIG. 4 is a timing chart for comparing a transition period during a mode transition from special reproduction (forward search) to normal reproduction when the conventional example and the present invention are used.

FIG. 5 is an explanatory diagram of an MPEG encoding system.

FIG. 6 is an explanatory diagram of an encoding / decoding processing sequence of the MPEG encoding method.

FIG. 7 is a block diagram showing an example of a conventional PCR (Program Clock Reference) decoding circuit.

FIG. 8 is an explanatory diagram of a decoding process of an ATV bitstream.

[Explanation of symbols]

101 Bitstream input terminal 102 PSI detection circuit 103 ID detection circuit 104 switch 105 PSI comparison circuit 106 PSI memory 107 switch 108 buffer memory 109 Bitstream output terminal 110 Mode transition signal input terminal 111 memory controller 112 logic circuit

Claims (8)

(57) [Claims] 1. Special reproduction data including control information for special reproduction for decoding data, and normal reproduction data including control information for normal reproduction for decoding data are independent in time series. A reproducing device for reproducing coded data including the normal reproduction data and the special reproduction data from a recording medium recorded as a normal reproduction data from the encoded data reproduced in the special reproduction mode. Detecting means for detecting the control information, storage means for storing the control information for normal reproduction detected by the detecting means, and storage means for storing the control information for normal reproduction in the special reproduction mode. A reproducing device comprising an updating means for updating the contents of the means with the latest detected control information for normal reproduction. 2. When the mode is changed from the special reproduction mode to the normal reproduction mode, and when the normal reproduction control information is stored in the storage means, the normal reproduction control information is read and output. 2. The reproducing apparatus according to claim 1, further comprising output control means for controlling as described above. 3. Special reproduction data including control information for special reproduction for decoding data and normal reproduction data including control information for normal reproduction for decoding data are independent in time series. A reproducing device for reproducing coded data including the normal reproduction data and the special reproduction data from a recording medium recorded as a normal reproduction data from the encoded data reproduced in the special reproduction mode. And a storage unit for storing the control information for normal reproduction detected by the detection unit. The control information corresponds to a plurality of programs included in the encoded data. A reproducing apparatus further comprising second detecting means for detecting that the control information for special reproduction has changed in the special reproduction mode and clearing the contents of the storage means. 4. The reproducing apparatus according to claim 1, wherein the encoded data is image data in which intra-frame encoded data and inter-frame encoded data are multiplexed. 5. The reproducing apparatus according to claim 1, wherein the encoded data is MPEG-2 encoded data. 6. The reproducing apparatus according to claim 1, wherein the encoded data is ATV encoded data. 7. Special reproduction data including special reproduction control information for decoding data and normal reproduction data including normal reproduction control information for decoding data are independent in time series. A reproducing device for reproducing coded data including the normal reproduction data and the special reproduction data from a recording medium recorded as a normal reproduction data from the encoded data reproduced in the special reproduction mode. And a storage means for storing the control information for normal reproduction detected by the detection means, wherein the control information is PSI. 8. The reproducing apparatus according to claim 1, 3 or 7, wherein the special reproduction mode is a fast-forward reproduction mode.