JP2001177833A - Data decoder and data decoding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously reproduce and output data dafter decoding even when streams are discontinuously received. SOLUTION: The decoder of this invention is provided with a video reproduction output buffer 14 that reproduces and outputs decoded data from a video decode buffer 13 in 2nd output timing. A reproduction output timing control section 20 generates the 2nd output timing synchronously with 1st output timing generated by a timing signal generating section 16 according to a result of discrimination by a frequency monitor section 21 that a transport stream is consecutive. The section 20 outputs the 2nd output timing generated just before according to a result of discrimination that a transport stream is not consecutive as the 2nd output timing while separating it from the synchronization of the 1st output timing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data decoding device and a data decoding method for decoding encoded data and reproducing and outputting the decoded data.

[0002]

2. Description of the Related Art MPEG (Moving Picture Experts Gro
upe) As a stream for handling video, a transport stream (MPEG2-
There are representative methods such as TS and TS (Transport Stream).

In the transport stream system, a PES (Packetized Elementary Stream) packet is divided into a plurality of transport packets (hereinafter, referred to as TS packets) and stored.

The decoder system can decode and reproduce MPEG video and MPEG audio by synthesizing a PES packet in a TS packet transmitted in such a form.

[0005] Here, the PES packet includes, as information for synchronizing, a time stamp ("time stamp") indicating when decoding / reproduction should be performed for each decoding / reproduction unit called each access unit of MPEG video and MPEG audio. Time Stamp), an SCR (System Clock Reference, a system clock reference value), and a PCR (Program Clock Reference, a program time reference value) that provide a time reference of the time stamp are added.

[0006] The time stamp is like a tag for time management of decoding / reproduction processing attached to each access unit, and is a PTS (Presentation Time Stamp).
And DTS (Decoding Time Stamp). PTS is time management information for reproduction output, and DTS is time management information for decoding.

[0007] The decoder system uses a PCR (Program Clock Referenc) attached to the synthesized PES packet.
e, various time information is created based on the program time reference value. Specifically, the decoder unit of the decoder system includes MPEG video and MPEG audio,
The value of TC (System Time Clock, a basic synchronization signal) is set and calibrated to an intended value based on PCR and SCR. Hereinafter, MPEG video will be described as a representative. Further, in the decoder system, in the timing signal generation section, the set / calibrated STC is compared with the DTS attached to the PES packet to generate MPEG video decode timing, and the STC is compared with the PTS. To generate the reproduction output timing. The decoder system decodes the MPEG video in accordance with the decode timing, and reproduces and outputs a video baseband signal which is data obtained by performing the decoding in accordance with the reproduction output timing. The reproduced video baseband signal is input to, for example, an image display device having a monitor on a display unit, and the image display device outputs an image to the monitor using the video baseband signal.

[0008]

By the way, the input of the stream to the decoder system may be discontinuous. For example, when the broadcast channel is switched or the mode of the VTR playback system changes, the stream input to the decoder system becomes discontinuous. At the time of mode transition of the VTR playback system,
For example, at the time of mode transition between so-called jog (JOG) reproduction and normal reproduction when reproducing what is once recorded on the recording medium.

[0009] However, when the stream input to the decoder system becomes discontinuous, for example, the PTS as the time management information becomes discontinuous, whereby the reproduction output of the video baseband signal also becomes discontinuous. .

Accordingly, the present invention has been made in view of the above situation, and has been made in consideration of the above circumstances, and has been made in consideration of the above circumstances. It is an object to provide an apparatus and a data decoding method.

[0011]

According to a first aspect of the present invention, there is provided a data decoding apparatus for generating a first output timing from a time reference value attached to encoded data. Output timing generating means, decoding means for outputting decoded data obtained by decoding encoded data according to the first output timing, and continuity discrimination for discriminating continuity and discontinuity of the encoded data on the time axis Means, a second output timing generating means for continuously generating a second output timing based on a determination result of the continuity determining means,
Reproduction output means for reproducing and outputting the decoded data output from the decoding means at the second output timing. The second output timing generation means generates a second output timing in synchronization with the first output timing based on a result of the determination that the encoded data is continuous, and determines that the encoded data is discontinuous. The immediately preceding output timing, which is the second output timing generated immediately before the encoded data is made discontinuous according to the result of the determination, is output as the second output timing separately from the synchronization with the first output timing.

The data decoding device having such a configuration decodes the encoded data at the first output timing generated by the first output timing generation means from the time reference value attached to the encoded data. The decoded data obtained by the decoding is output by the decoding means, and the second output timing generation means outputs the second output timing Are continuously generated, and at the second output timing, the decoded data output from the decoding means is reproduced and output by the reproduction output means.

Here, the second output timing generating means determines the first output timing based on the result of the determination that the encoded data is continuous.
The second output timing is generated in synchronization with the output timing of (i), and immediately before the second output timing generated immediately before the encoded data is made discontinuous based on the determination result that the encoded data is discontinuous. The output timing is separated from the synchronization with the first output timing and output as the second output timing.

Accordingly, the data decoding apparatus generates the second output timing as the output timing of the reproduction output means as continuous even if the encoded data is discontinuous on the time axis. can do.
Therefore, the decoded data output from the reproduction output means to the subsequent stage is always continuous.

Further, in order to solve the above-mentioned problem, a data decoding method according to the present invention generates a first output timing from a time reference value attached to encoded data,
At the first output timing, decoded data obtained by decoding the encoded data is output, and continuity and discontinuity of the encoded data on the time axis are determined, and the determination result that the encoded data is continuous Generates the second output timing in synchronization with the first output timing, and generates the second output timing immediately before the encoded data is discontinued based on the determination result that the encoded data is discontinuous. Is output as the second output timing separately from the synchronization with the first output timing, and at the transition point on the time axis from discontinuity to continuity in the encoded data,
A second output timing shifted from the first output timing by a phase difference between the immediately preceding output timing and the first output timing is generated, and the decoded data is reproduced and output at the second output timing.

Thus, in the data decoding method, even when the encoded data is discontinuous on the time axis, the second output timing that is the output timing of the reproduction output is generated as continuous. be able to. Therefore, the decoded data is always continuous.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. In this embodiment, the present invention is applied to an MPEG (Moving Picture Experts Groupe).
The present invention is applied to a decoding device that decodes a transport stream (MPEG2-TS, TS: TransportStream) that is a video stream and reproduces and outputs a video baseband signal obtained by decoding.

As shown in FIG. 1, the decoding device comprises a video decoder section 10 and a reproduction output timing control section 20.

The video decoder section 10 has a PES (Packet)
It is provided with a combined elementary stream, a video decoder 12, a video decode buffer 13, a video reproduction output buffer 14, a PLL circuit 15, and a timing signal generator 16.

The reproduction output timing control unit 20
Frequency monitoring unit 21, subtractor 22, delay unit 23, phase comparison unit 24, switch 25, VCO (Voltage Controlled O)
sillator) 26 and a delay buffer 27.

Here, the PLL circuit 15 and the timing signal generating unit 16 transmit PES (Packetiz) which is encoded data.
(ed Elementary Stream) packet constitutes a first output timing generation means for generating a first reproduction output timing which is a first output timing from a PCR (Program Clock Reference) which is a time reference value attached to the packet.

The video decoder 12 and the video decode buffer 13 constitute a decoding means for outputting a video baseband signal which is decoded data obtained by decoding encoded data at the first reproduction output timing.

The frequency monitoring section 21 constitutes a continuity determining means for determining continuity and discontinuity of the encoded data on the time axis.

The reproduction output timing control unit 20
A second output timing generation means for continuously generating a second reproduction output timing, which is a second output timing, based on the determination result of the frequency monitoring unit 21 is configured. Specifically, the reproduction output timing control unit 20 generates the second reproduction output timing in synchronization with the first output reproduction timing based on the determination result that the transport stream is continuous, and The immediately preceding output timing, which is the second playback output timing generated immediately before the transport stream is made discontinuous according to the result of the determination that the stream is continuous, is separated from the first output timing in synchronization with the second playback output timing. Output as

Further, the video reproduction output buffer 14 controls the video decoding buffer 1 according to the second output timing.
3 constitutes a reproduction output means for reproducing and outputting the video baseband signal which is the decoded data outputted from 3.

The decoder decoding device includes a PES combining section 11
, A transport stream packet (hereinafter, referred to as a TS packet) is input. This TS packet is
The video MPEG stream and the MPEG audio stream are stored, but in the following description, MPEG video will be described as a representative.

The TS packet includes a PID (Packet Identifier).
), which is information indicating the attribute of the individual stream of the packet. In addition, the adaptation field of the TS packet includes a PCR (Pr
ogram Clock Reference).

The PES synthesizing unit 11 calculates the PI of the TS packet.
Separating the transport stream based on D,
PES (Packetized Elementary Strea ...
m) Combining packets to extract MPEG video. The extracted MPEG video is output to the video decoder 12.

More specifically, the PES synthesizing unit 11 aggregates the packets separated in units of transport streams as shown in FIG. 2B, as shown in FIG. The packets are combined to extract the MPEG video.

In the header area of the PES packet, PTS (Presentation Time Stam) which is reproduction output time management information is provided.
p) and DTS (Decoding Time)
Stamp).

The PLL circuit 15 has a reference clock for the system based on the 27 MHz crystal and the PCR.
Generate TC (System Time Clock). The STC is output to the timing signal generator 16.

The timing signal generator 16 compares the STC with the PTS and the DTS attached to the PES packet, and generates a decode output timing and a first reproduction output timing.

The video decoder 12 decodes the MPEG video output from the PES synthesizing unit 11 at the decoding timing which is the decoding output timing generated by the timing signal generating unit 16. The decoded data is output to the video decode buffer 13.

The video decoding buffer 13 temporarily stores a video baseband signal, which is decoded data obtained by the video decoder 12, and outputs the video baseband signal to the video reproduction output buffer 14 at a first reproduction output timing. Department. That is, the video decode buffer 13
Buffers the decoded data output from the video decoder 12 in accordance with the decode timing, and stores the data in the subsequent video playback output buffer 1 in accordance with the first playback output timing generated by the timing signal generator 16.
4 is output.

The video reproduction output buffer 14 is a second storage means for temporarily storing the decoded data output from the video decoder 12 and reproducing and outputting the decoded data at the second reproduction output timing. Specifically, the video reproduction output buffer 14 buffers a video baseband signal, which is data output from the video decode buffer 13 at the first reproduction output timing, and is generated by the reproduction output timing control unit 20. Output to the subsequent stage according to the second reproduction output timing. For example, an image display device or the like having a monitor is connected to the subsequent stage of the video reproduction output buffer 14 so that the image display device can connect to the monitor based on the video baseband signal output from the video decoder unit 10. Output images.

The reproduction output timing control section 20 always generates the second reproduction output timing continuously, and the decoding device reproduces and outputs the video baseband signal based on the second reproduction output timing. By providing the buffer 14, the video baseband signal can be reproduced and output at the subsequent stage without making it discontinuous. Thus, the video baseband signal is always output as a continuous signal even when the PTS has discontinuity.

Hereinafter, the second reproduction output timing for controlling the data output timing of the video reproduction output buffer 14 will be described.

As described above, when the channel is switched or when V
At the time of the mode transition of the TR reproduction system, the stream input to the video decoder unit 10 may be discontinuous. In this case, discontinuity occurs in the PTS, which is output from the timing signal generation unit 16. Discontinuity also occurs in the first reproduction output timing. To explain using a decoding device to which the present invention is applied, conventionally, data decoded by the video decode buffer 13 is reproduced and output in accordance with the reproduction output timing generated by the timing signal generation unit 16. This means that the video baseband signal is discontinuous and has been output to an image display device or the like provided at the subsequent stage of the video decoder unit 10. As a result, the video output image may be interrupted at the time of channel switching or VTR playback mode transition. For example, in the PTS discontinuous section, the reproduction output timing is discontinuous as shown in FIG.

The decoding device further comprises a video reproduction output buffer 14 which takes an output timing based on the second reproduction output timing at a subsequent stage of the video decode buffer 13, and the reproduction output timing control section 20 always keeps the second reproduction output timing continuous. This allows the video baseband signal to be output to the subsequent stage without discontinuity.

The reproduction output timing control section 20 generates the second reproduction output timing based on the first reproduction output timing generated by the timing signal generation section 16. Then, the reproduction output timing control unit 20
When the TS is continuous, when the PTS is discontinuous, and when the discontinuous PTS transitions continuously, the second reproduction output timing is generated accordingly. Each component of the output timing control unit 20 will be described in each case.

As shown in FIG. 1, in the reproduction output timing control section 20, the first reproduction output timing is input to each of the frequency monitoring section 21, the delay output section 23, and the subtractor 22.

First, when the PTS is continuous and in a steady state, the first reproduction output timing input to the delay output unit 23 is delayed by a predetermined
The signal is output to the phase comparison unit 24 forming a part of the LL (phase-locked loop). Here, the delay time of the first reproduction output timing in the delay output unit 23 is determined by the delay time held in the delay buffer 27.
The delay time held by the delay buffer 27 will be described later.

Here, the phase comparison unit 24 is connected to the VCO
26 constitutes a PLL as a synchronization means for synchronizing the second reproduction output timing with the first reproduction output timing.

That is, the phase comparison section 24 compares the phases of the first reproduction output timing, and the VCO 26 outputs a signal having a constant period according to the comparison result. This V
A signal with a constant cycle output from the CO 26 is the second reproduction output timing. The second reproduction output timing output from the VCO 26 is taken into the phase comparison unit 24 as a feedback signal. As described above, the phase comparison unit 24 and the VCO 26 constitute a PLL, whereby the second reproduction output timing is generated in synchronization with the first reproduction output timing.

A switch 25 is provided between the phase comparator 24 and the VCO 26 to enable connection and disconnection between the phase comparator 24 and the VCO 26.

The opening and closing of the switch 25 is controlled by a frequency monitor 21 for monitoring the first reproduction output timing. The frequency monitoring unit 21 is configured to monitor whether or not the input signal has a fixed period, as a function of the continuity determination unit. For the purpose, it is monitored whether or not the first reproduction output timing is continuous. Then, as long as the first reproduction output timing is continuous, that is, as long as the PTS is continuous, the frequency control unit 21 keeps the switch 25 closed as described above to change the discontinuous PTS. If it is detected, the switch 25 is opened and the phase comparison unit 24 and the VCO 2
6 is disconnected.

As described above, the frequency monitoring unit 21 functions as continuity determining means, and controls the operation of the PLL by controlling the opening and closing of the switch 25 based on the result of determining whether the PTS is continuous or discontinuous. Thus, it also functions as a synchronization control unit for generating the second output timing.

A switch 25 controlled by such a frequency monitor 21 is provided between the phase comparator 24 and the VCO 6.
As long as the PTS is continuous and input, the phase comparator 24 and the VCO 6 are connected and operate as a PLL.

The second reproduction output timing output from the VCO 26 is input to the subtracter 22. The first reproduction output timing is input to the subtractor 22, and the difference between the first reproduction output timing and the second reproduction output timing, that is, the first reproduction output timing and the second reproduction output timing are input to the subtractor 22. The phase difference from the timing is taken. Then, the phase difference obtained by the subtractor 22 is held in the delay buffer 27 as a delay time.

The reproduction output timing control section 20 delays the delay output section 23 to which the first reproduction output timing is first inputted in the reproduction output timing control section 20 by the delay time held in the delay buffer 27,
The delayed signal is converted to a phase comparison unit 24 constituting a PLL.
To generate the second reproduction output timing.

FIG. 3 is a timing chart of a series of processing as described above. A PTS continuous section (a PTS before entering a PTS discontinuous section) is a section in which PTSs are continuously input. Input continuous section)
The delay amount held in the delay buffer 27, the actual delay amount of the second reproduction output timing output from the VCO 26,
Specifically, the operating states of the switches are as follows.

When the first reproduction output timing is output as shown in FIG. 3A and the second reproduction output timing is output as shown in FIG. As shown in (C) of FIG. 3, a certain delay time A is held in the delay buffer 27 as the difference amount output from. As a result, the second reproduction output timing output from the VCO 26 is delayed from the first reproduction output timing by the delay time A as shown in FIG. At this time, the switch 25 is closed.
As shown in FIG. 3E, the phase comparator 24 and the VCO 2
6 is connected to form a PLL, so that the second
Is output in synchronization with the first playback output timing.

As described above, when the PTS is continuous, the reproduction output timing control section 20 generates the second reproduction output timing based on the input first reproduction output timing. I have. When the PTS is continuous, the reproduction output timing control unit 20 generates the second reproduction output timing by configuring the PLL, so that the second reproduction output timing is the first reproduction output timing. Synchronized with the reproduction output timing, the signal is a signal in which a constant phase difference is maintained from the first reproduction output timing. The reproduction output timing control unit 20 outputs the second reproduction output timing generated in this way to the video reproduction output buffer 14 of the video decoder unit 10.

The video playback output buffer 14 outputs the video baseband signal output from the video decoding buffer 13 at the preceding stage to the subsequent stage in accordance with the second playback output timing generated by the playback output timing controller 20.

Next, a case where the PTS is discontinuous from the state where the PTS is continuous as described above will be described.

When a discontinuity occurs in the PTS, the frequency monitoring unit 21 immediately opens the switch 25 and shuts off the phase comparison unit 24 and the VCO 26. As a result, the PLL loop is disconnected, that is, the operation of the PLL is stopped, and
The CO 26 outputs the second reproduction output timing immediately before disconnection of the PLL, and enters a self-running state based on the second reproduction output timing. That is, the second reproduction output timing is output as a signal separated from the synchronization of the first reproduction output timing.

PT, which is a section where discontinuity has occurred in PTS
In the S discontinuous section, the delay amount held in the delay buffer 27, the actual delay amount of the second reproduction output timing output from the VCO 26, and the operation state of the switch are specifically as follows.

In the PTS discontinuous section, the first reproduction output timing cannot be obtained as shown in FIG. 3A, while the second reproduction output timing is not obtained as shown in FIG. As described above, it is obtained as a self-propelled state. At this time, the delay time held in the delay buffer 27 is as shown in FIG.
As shown in the middle (C), the delay time B and the delay time C gradually increase.

On the other hand, as shown in FIG. 3 (E), the switch 25 is opened, the PLL is disconnected, and as shown in FIG. 3 (D), the delay time immediately before the PLL disconnection is output from the VCO 26. A second reproduction output timing is output.

As described above, when a discontinuity occurs in the PTS, the reproduction output timing control unit 20 continues to output the second reproduction output timing immediately before the discontinuity occurs in the PTS.

The video reproduction output buffer 14 outputs the video baseband signal output from the preceding video decode buffer 13 in accordance with such second reproduction output timing.

Therefore, in the video decoder section 10, the PT
Even when S is discontinuous and the first playback output timing is not output to the video decoder buffer 13, the video playback output buffer 14 is controlled by the second playback output timing generated by the playback output timing controller 20. Can be output from Thereby, PTS
, Data is always output from the video reproduction output buffer 14.

When the time until the PTS is continuous is long, for example, when the channel switching time is long, the video baseband signal output from the video reproduction output buffer 14 is the same as that of the same image. Become. As a result, the immediately preceding image is output as a still image until a new channel is switched. If the time until the PTS is continuous is long, a video baseband signal serving as a blue-back image can be output. Further, by increasing the buffer size of the video reproduction output buffer 14, even when the time until the PTS is made continuous is long, there is no need to output a still image or display a blue-back image as described above. The reproduced image can be reproduced.

Next, a case where the discontinuous PTS becomes continuous will be described.

When the PTS becomes continuous again, a new first PTS based on the new PTS is sent to the reproduction output timing control unit 20.
Of the reproduction output timing is started. Thus, the delay time between the new first reproduction output timing and the new reproduction reproduction timing is written in the delay buffer 27.

At the transition point where the PTS changes from discontinuous to continuous, the second reproduction output timing (immediate output timing) output in the self-running state as described above and the first PTS reference of the new PTS reference. The phase difference from the reproduction output timing is held in the delay buffer 27. Then, the switch 25 is closed again by the frequency monitoring unit 23 where the first reproduction output timing is detected.
4 and the VCO 26 again operate the PLL, and the delay output unit 23 outputs a signal whose first reproduction output timing has been delayed by the delay time of the delay buffer 27 to the phase comparison unit 24 configuring the PLL as such. As a result, the second reproduction output timing maintaining the phase relationship with the new first reproduction output timing is output from the VCO 26. That is, at the transition point of the PTS from discontinuity to continuation, the VCO 26 outputs the second output timing shifted from the first reproduction output timing by the phase difference between the immediately preceding output timing and the first reproduction output timing. By operating the PLL again, the second reproduction output timing is output in synchronization with the first reproduction output timing.

In the PTS continuous section in which the PTS becomes continuous again, the delay amount held in the delay buffer 27, VCO2
The actual delay amount of the second reproduction output timing and the operation state of the switch output from the switch 6 are as follows.

Since a new first reproduction output timing is output as shown in FIG. 3A and a second reproduction output timing is output as shown in FIG. 3B, the subtractor The difference amount output from the delay buffer 2
7, a delay time D is held as shown in FIG. As a result, the second reproduction output timing output from the VCO 26 is delayed from the first reproduction output timing by a new delay time D, as shown in FIG. Further, the switch 25 is closed again, and as shown in FIG.
O26 is connected to form a PLL.

As described above, when the PTS becomes continuous again, the reproduction output timing control unit 20 outputs a new PTS.
A second reproduction output timing is generated based on the new reference first reproduction output timing. Then, in the reproduction output timing control unit 20, the PLL operates again, so that the second reproduction output timing is again synchronized with the first reproduction output timing and a constant phase is maintained from the first reproduction output timing. Timing.

The video reproduction output buffer 14 outputs the video baseband signal output from the video decoding buffer 13 at the preceding stage according to such a second reproduction output timing.

Further, the first reproduction output timing and the second reproduction output timing
Is the reproduction output timing for each frame, and the buffer size of the video reproduction output buffer 14 is set to a size corresponding to one frame.
Accordingly, the second reproduction output, which is a reference for reading from the video reproduction output buffer 14, is not limited by a phase difference with respect to the first reproduction output timing, which is a reference for writing to the video reproduction output buffer 14. Timing can be generated.

It should be noted that the video reproduction output buffer 14
The capacity is not limited to the frame equivalent size, and the capacity can be determined according to the first reproduction output timing and the second reproduction output timing. That is, the first reproduction output timing and the second reproduction output timing are 1
If the playback output timing is set for each field, the buffer size of the video playback output buffer 14 is set to 1
Field equivalent size. Thus, even when the first and second reproduction output timings are set to the reproduction output timing for each field, the second reproduction output timing is not limited by the phase difference with respect to the first reproduction output timing. The reproduction output timing can be generated.

As described above, the reproduction output timing control unit 20 can always output the second reproduction output timing continuously even when a discontinuity occurs in the PTS. That is, the reproduction output timing control unit 20
Control is performed so that the second reproduction output timing is continuous even if the first reproduction output timing is discontinuous.

As a result, even when the PTS has a discontinuity and the first reproduction output timing has a discontinuity, the decoder device always responds to the generated second reproduction output timing. The video baseband signal can be output from the video reproduction output buffer 14 without discontinuity. Then, when the PTS changes from discontinuous to continuous again, the decoder can generate the second reproduction output timing in synchronization with the first reproduction output timing based on the new PTS reference.

Therefore, the decoder device can prevent the video output from the image display device from being interrupted at the time of channel switching or VTR playback system mode transition.

In the above embodiment, the decoder device determines whether the continuation or discontinuity of the encoded data on the time axis is PT
It is determined based on the continuity and discontinuity of S. However, the present invention is not limited to this, and the decoder device may determine whether the continuity and discontinuity of the encoded data on the time axis are due to the continuity and discontinuity of the DTS as the decoding time management information and the PCR as the program time reference value. Can also be determined.

FIGS. 4 and 5 show the data structure of a TS packet and the data structure of a PES packet employed in MPEG2.

The data structure of the TS packet is composed of a header and a payload as shown in FIG.

As shown in FIG. 4B, the header shown in FIG. 4A includes a synchronization byte, an error indication, an error indication, a payload unit start indication, a packet priority,
It has a PID, scramble control, adaptation field control, continuity counter, and adaptation field.

The adaptation field shown in FIG. 4B is provided with PID (Packet Identification) which is the above-mentioned stream identification information. That is, the adaptation field corresponds to FIG.
As shown in the middle (C), it has an adaptation field length, a discontinuity display, a random access display, an elementary stream display, a five flag, an optional field, and a stuffing byte.

In the optional field shown in FIG. 4C, a PCR (Program Clock Reference) which is the above-described clock synchronization reference is added. That is, as shown in FIG. 4 (D), the optional field includes PCR, 0PCR (Original P
CR), splice countdown, transport private data length, transport private data, adaptation private data length and data, 3 flags, and optional fields.

The optional field shown in (D) of FIG. 4 has LTW as shown in (E) of FIG.
(Long Time Window) valid flag, LTW offset,
It has a PW (piecewise) rate, a splice type, and a next access unit DTS.

The data structure of the PES packet is, as shown in FIG. 5A, a packet head start code, a stream ID, a PES packet length, an optional PE
It has an S header and a PES packet data byte.

As shown in FIG. 5B, the optional PES header shown in FIG.
0 ", PES scramble control, PES priority, data alignment display, copyright, original / copy, 7 flag, P
It has an ES header data length, an optional field, and data padding “Oxff”.

The optional fields shown in FIG. 5B are accompanied by PTS (Presentation Time Stamp) which is the above-mentioned reproduction output time management information and DTS (Decoding Time Stamp) which is the decoding time management information. Have been. That is, the optional field is as shown in FIG.
As shown in the middle (C), PTS, DTS, ESCR (El
ementary Stream Clock Reference), ES (Elementar
y Stream) rate, DSM (Digital Storage Media)
Trick mode control data, additional copy information, previous PES
CRC (Cyclic Redundancy Code) of the packet and P
Has ES extension.

As shown in FIG. 5D, the PES extension shown in FIG. 5C is composed of PES private data, a pack field, a pack header field having a pack header, a program packet sequence, Counter field and "01", P-
A P-STD buffer having an STD (Program System Target Decoder) buffer scale and a P-STD,
It has a PES extension field length and PES extension field data.

As shown in FIG. 5E, the program packet sequence and the counter field shown in FIG. 5D contain the program packet sequence counter, MPEG1 and MPEG2 identification, and data padding. Have a long.

The decoding device synthesizes the PES packet from the TS packet having the above data structure,
It decodes and reproduces and outputs the video stream and audio stream stored in the PES packet.

[0089]

The data decoding apparatus according to the present invention decodes encoded data at a first output timing generated by a first output timing generating means from a time reference value attached to the encoded data. The decoded data obtained as a result is output by the decoding means, and based on the determination result of the continuity and discontinuity on the time axis of the encoded data by the continuity determination means,
The second output timing generation means continuously generates a second output timing, and the second output timing causes the decoded data output from the decoding means to be reproduced and output by the reproduction output means. The timing generation means determines the first based on the result of the determination that the encoded data is continuous.
The second output timing is generated in synchronization with the output timing of (i), and immediately before the second output timing generated immediately before the encoded data is made discontinuous based on the determination result that the encoded data is discontinuous. The output timing is separated from the synchronization with the first output timing and output as the second output timing.

Thus, even when the encoded data is discontinuous on the time axis, the data decoding apparatus generates the second output timing as the output timing of the reproduction output means as a continuous one. can do.
Therefore, the decoded data output from the reproduction output means to the subsequent stage is always continuous.

Further, in the data decoding method according to the present invention, the first output timing is generated from the time reference value attached to the encoded data, and the first output timing is generated by the first output timing.
The decoded data obtained by decoding the encoded data is output, the continuity and discontinuity of the encoded data on the time axis are determined, and the first output timing is determined based on the determination result that the encoded data is continuous. Synchronize to generate a second output timing,
The immediately preceding output timing, which is the second output timing generated immediately before the encoded data is made discontinuous based on the determination result that the encoded data is discontinuous, is separated from the second output timing in synchronization with the first output timing. At the transition point from discontinuity to continuity on the time axis in the encoded data, the output timing is shifted from the first output timing by the phase difference between the immediately preceding output timing and the first output timing. 2 is generated, and the decoded data is reproduced and output at the second output timing, so that even if the encoded data is discontinuous on the time axis, the output timing of the reproduced output and the The second output timing can be generated as continuous. Therefore, the decoded data is always continuous.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a data decoding device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a PES packet and a TS packet.

FIG. 3 is a time chart showing changes in signals and the like in a reproduction output timing control unit of the data decoding device.

FIG. 4 is a diagram showing a data structure of a TS packet.

FIG. 5 is a diagram showing a data structure of a PES packet.

[Explanation of symbols]

Reference Signs List 10 video decoder device, 11 PES synthesis unit, 12
Video decoder, 13 Video decode buffer, 1
4 video playback output buffer, 15 PLL circuit, 16
Timing signal generator, 20 playback output timing controller, 21 frequency monitor

Claims (9)

[Claims] A first output timing generating means for generating a first output timing from a time reference value attached to the encoded data; and decoding the encoded data by the first output timing. Decoding means for outputting decoded data obtained in the above manner; continuity determining means for determining continuity and discontinuity on the time axis of the encoded data; and a second output based on a result of the continuity determining means. A second output timing generating means for continuously generating timing; and a reproduction output means for reproducing and outputting decoded data output from the decoding means by the second output timing. The generating means generates a second output timing in synchronization with the first output timing based on a determination result that the encoded data is continuous, and The immediately preceding output timing, which is the second output timing generated immediately before the encoded data is discontinued based on the result of the determination that the data is continuous, is separated from the synchronization with the first output timing and is set as the second output timing. A data decoding device for outputting. 2. The second output timing generation means,
A synchronizing means for synchronizing the second output timing with the first output timing, and controlling the operation of the synchronizing means based on a result of determining whether the encoded data is continuous or discontinuous on a time axis, Synchronization control means for generating the second output timing, wherein the synchronization control means operates the synchronization means based on the determination result that the encoded data is continuous, and outputs the first output timing. The second output timing synchronized with the above is generated, and in the determination result that the encoded data is discontinuous, the synchronization means is not operated,
The immediately preceding output timing is output as a second output timing, and at a transition point on the time axis from discontinuity to continuity in the encoded data, only a phase difference between the immediately preceding output timing and the first output timing is obtained. 2. The data decoding device according to claim 1, wherein a second output timing shifted from the first output timing is generated. 3. The synchronizing means includes a PLL (Phase-Locked).
Loop), the second output timing is set to the first output timing.
3. The data decoding apparatus according to claim 2, wherein the data decoding apparatus synchronizes with the output timing. 4. The first output timing generation means,
Generating a decoding output timing and a reproduction output timing,
Outputting the reproduction output timing as the first output timing; the decoding means decoding a coded data at the decoded output timing; and a decoding unit decoding the coded data by the decoding unit. A first storage unit for temporarily storing data and outputting the data to the reproduction output means at the first output timing, wherein the reproduction output means temporarily stores the decoded data output from the decoding means. 2. The data decoding device according to claim 1, wherein the data decoding device is a second storage unit that stores the data and reproduces and outputs the data at the second output timing. 5. The decoding means according to claim 1, wherein said decoding means comprises an MPEG2 (Moving P
The Expert Output Group 2) decodes the encoded data, which is a transport stream according to the standard, and the first output timing generation means converts the decoded output timing to the time reference attached to the transport stream. Generated based on a program time reference value (Program Clock Reference, PCR) and decoding time management information, which are reference values,
The above-mentioned program time reference reference value and the playback output time management information (Pres
entation Time Stamp (PTS), and the continuity determining means determines whether the coded data is continuous or discontinuous on the time axis by using the program time reference reference value, the decoding time management information, or the reproduction. 5. The data decoding apparatus according to claim 4, wherein the determination is made based on whether the output management information is continuous or discontinuous. 6. A first output timing is generated from a time reference value attached to encoded data, and decoded data obtained by decoding the encoded data is output at the first output timing. Determining whether the encoded data is continuous or discontinuous on the time axis, and generating a second output timing in synchronization with the first output timing based on the determination result that the encoded data is continuous. According to the result of the determination that the encoded data is discontinuous, the immediately preceding output timing, which is the second output timing generated immediately before the encoded data is discontinued, is separated from the synchronization with the first output timing. Second
At the transition point from discontinuity to continuity on the time axis in the encoded data,
Generating a second output timing shifted from the first output timing by a phase difference between the immediately preceding output timing and the first output timing, and reproducing and outputting the decoded data based on the second output timing. Characteristic data decoding method. 7. A PLL (Phase-Locked Loop)
7. The data decoding method according to claim 6, wherein the second output timing is synchronized with the first output timing. 8. The data decoding method according to claim 6, wherein a decoding output timing and a reproduction output timing are generated from the reference reference value, and the reproduction output timing is output as the first output timing. 9. The method according to claim 1, wherein the encoded data is MPEG2
A transport stream in the (Moving Picture Experts Group2) standard is decoded, and the decoded output timing is determined by a program clock reference value (Program Clock Reference, which is the time reference value attached to the transport stream). PCR) and decoding time management information, and generates the playback output timing based on the program time reference value and playback output time management information (Presentation Time Stamp, PTS) attached to the transport stream. Generating and determining the continuity and discontinuity of the encoded data on the time axis based on the continuity and discontinuity of the program time reference value, the decoding time management information, or the reproduction output management information. The data decoding method according to claim 6.