JPH09128894A - Synchronization device of video and voice processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly synchronize the output timing of an audio signal with a video signal as much as possible with a simple circuit constitution in the case of respectively decoding and outputting a video code string and an audio code string. SOLUTION: A time stamp part processing part 28 fetches the first PTS (a presentation time stamp) to be included in the voice code string to compare the content of PTS with the count value of a time stamp counter. Then, when they coincide, the part outputs a timing control signal to a buffer part 31 so as to permit the output of an audio circuit and thereafter maintains permissions of audio outputs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a decoding output of a video code string and an audio code when a reproduction code string in which a data-compressed video code string and an audio code string are sent in time division The present invention relates to a synchronizing device of a video / audio processing device adapted to be synchronized with a decoded output of a column.

[0002]

2. Description of the Related Art As an information recording system for optical discs,
There is a method of recording a data-compressed video code string and audio code string in a time division manner. When reproducing an optical disc of this type, it is necessary to synchronize both when decoding and outputting a video code string and an audio code string in a video decoder and an audio decoder.

As a conventional method, for example, a counter is synchronized with a synchronizing signal of a video code string to perform counting, and the frame number attached to each frame of the audio code is compared with the count value of the counter. Performed, and depending on the comparison result,
The output timing of the decoded audio signal was planned.

[0004]

When the video code string and the audio code string are input as described above and the two are synchronized, it is necessary to consider the following preconditions. The circuit configuration is complicated because the synchronization relationship is frequently detected and the operation for maintaining the synchronization is performed. Further, the demodulated data taken in from the optical disc or the transmission path is first subjected to processing such as error correction in the signal processing section. When this error correction is impossible, an error flag is output from the signal processing unit, and the data corresponding to this error flag is usually processed so as not to be used in the decoding process.

However, the conventional circuit that receives the video code string and the audio code string as input and maintains the synchronization relationship between them does not take measures when many errors occur in the input data, and the audio signal is output at the wrong timing. Was sometimes output. In addition, the synchronization relationship between video and audio remains largely erroneous and may continue for a long time until the next synchronization is obtained.

Therefore, in the present invention, when the video code string and the audio code string are respectively decoded and output, the output timing of the audio signal can be synchronized with the video signal as accurately as possible with a simple circuit configuration. An object is to provide a synchronizing device for a video / audio processing device.

[0007]

According to the present invention, since the synchronization processing is performed every time the synchronization information arrives, a circuit becomes complicated and other problems occur. Therefore, the synchronization processing is performed only at the beginning or in a specific period. I am trying.

Specifically, a specific packet of the data compressed video code string and each packet of the data compressed audio code string are each provided with a presentation time stamp as time information for synchronizing video and audio. (Hereinafter referred to as PTS) is described, which is a device to which a reproduction code sequence is sent in which the video code sequence and the audio code sequence are transmitted in a time division manner. A video decoder for decoding, an audio decoder for taking in and decoding the audio code string, a time stamp counter means for counting a reference clock in synchronization with a predetermined reproduction timing of the reproduction code string, and the audio decoder included in the audio code string. A procedure for taking in the PTS and determining the relationship between the contents of the PTS and the count value of the time stamp counter means. If the PTS and the count value first have a predetermined relationship, the PTS control unit outputs the output timing control signal of the audio decoder and thereafter maintains the audio output permission. . With this configuration, the load on the circuit for maintaining the synchronization relationship is reduced and the configuration can be simplified.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an optical disc reproducing apparatus according to the present invention. Optical disc 1
1 is rotationally controlled by a motor 12 controlled by a servo system (not shown). Optical pickup device 2
The optical signal picked up by 1 is converted into an electric signal and introduced into the signal processing unit 22. The signal processing unit 22 includes a demodulation unit 23 and an error correction processing unit (ECC processing unit) 2
4 is included. The signals output from the signal processing unit 22 include demodulated data and error flags.

The demodulated data output from the signal processing unit 22 includes, for example, video code, audio code, and other codes. Therefore, the demultiplexer 25 distributes the video code to the video decoder 26 and distributes the audio code to the audio decoder 27 and supplies the audio code.

A presentation time stamp (PTS), which will be described later, is supplied to the time stamp processing unit 28. The video signal decoded by the video decoder 26 is input to the buffer unit 29, the output time point is controlled by the output timing signal from the time stamp processing unit 28, and is output to the output terminal 30. The audio signal decoded by the audio decoder 27 is also input to the buffer unit 31, the output timing is controlled by the output timing signal from the time stamp processing unit 28, and is output to the output terminal 32.

Reference numeral 33 denotes a system controller, which controls the operation of the entire apparatus, to which an operation input interface 34 is also connected. When a playback start signal is sent from the remote controller, the operation input interface 3
A reproduction command signal is input to the system controller 33 through 4. In response to this, the control of the motor 12 and the operation of the signal processing unit 22 are started. When the reproduction is started, the system controller 33 controls the time stamp unit 28 based on the control information read from the disc to perform the clock count, and thus the absolute time can be set.

By the way, the video signal and the audio signal recorded on the optical disk 11 are coded into a video code and an audio code, packed, modulated and recorded. Therefore, each video code and audio code, which are signals reproduced from the optical disc 11 and demodulated, are packed, and one pack is, for example, one packet. A pack header is arranged at the head of one pack. Furthermore, a packet header is placed at the beginning of the packet (see FIG. 2).

A presentation time stamp (PTS) is described in a specific packet of the video code. A presentation time stamp (PTS) is described in each voice code packet. This PTS is for synchronizing the output of the video signal and the audio signal.

For example, a time stamp counter section that is reset by control information of a specific pack from the time when reproduction of an optical disc is started and counts a reference clock is provided for each of the audio system and the video system. Then, in the audio system, the output of the audio buffer unit 31 is permitted when the value of the counter of the time stamp counter unit and the PTS included in the packet of the audio code match.

Also in the video system, there is provided a time stamp counter section which is set to a predetermined value by the control information of a specific pack and counts the reference clock. Then, when the value of this counter and the PTS included in the specific packet of the video code match, the output of the video buffer unit 29 is permitted.

The absolute time information in the time stamp counter section of the video system and the audio system is initialized by the system controller 33. However, when special playback such as fast forward or slow playback is performed, the correction function is activated and the absolute time information is corrected.

FIG. 3 shows a time stamp counter unit 41 of the audio system, a PTS acquisition circuit 42, and a comparator 43. The time stamp counter unit 41 is set to a predetermined value at a specific timing of the video code, for example, a timing corresponding to vertical synchronization, and counts the reference clock. The time stamp counter unit 41 may count the reference clock from the video decoder 26, or has its own PLL circuit that is phase-synchronized with the reference clock and counts the clock generated here. Good.

Here, the PTS fetch circuit 42 is set so as to fetch only the PTS that arrives first when the reproduction of the optical disc 11 is started. This setting can be realized by, for example, a logic circuit that gives a capture permission for a certain period from the start of reproduction.

At this time, the PTS and time counter unit 41
When the output and the output of 1 match, the matching pulse is obtained from the comparator 43. This coincidence pulse is given to the buffer unit 31 of FIG. 1 as an output timing control signal to give permission for decoding output. After that, the buffer unit 31 continuously enters the output permission state.

In the case of such a system, a video code string and an audio code string are input, and in order to obtain a synchronization relationship between them,
The synchronization detection and the output timing setting process are performed only in the first period, and thereafter, the audio signal is continuously output. Therefore, even if many errors occur in the data when the code string is demodulated, the output of the video signal and the audio signal is continued as it is. The synchronization detection process for each packet is not performed. As a result, even if a data error occurs, only the output of the audio signal is disturbed at that time, and if there is no error, the video signal and the audio signal are in synchronization. if,
When the synchronization detection process is performed for each packet, when the data error occurs, the first disturbance of the audio signal may occur and the synchronization relationship may shift, and when the synchronization is made again, the second synchronization may occur. Disturbance of the audio signal will occur. However, in the system of the present invention, when the data error occurs, the first disturbance of the audio signal occurs. Usually, such a disturbance is subjected to a muting process by the error flag information.

FIG. 4 shows another embodiment of the time stamp processing unit 28. The above embodiment of FIG. 3 was designed assuming that the first PTS did not generate any error. However, there may be a data error in the first PTS. Therefore, in the second embodiment of the present invention, the following measures are taken.

That is, a switch 44 is provided on the input side of the PTS fetch circuit 42 so that the PTS fetch can be restricted. The other part is
Since the configuration is the same as that of FIG. 3, the same reference numerals are given.
The switch 44 is used as follows. First, when playback of the optical disc 11 starts, PTS
Only the PTS that arrives first is made to be taken in by the take-in circuit 42. However, when the error flag is output from the signal processing unit 22, the switch 44 is turned off and the PTS in error is taken. It is designed not to be crowded. The switch 44 is in the ON state when the reproduction is started, but is in the OFF state when the error flag is given. Then the error flag is erased and P
When PTS is captured by the TS capture circuit 42,
It is logically configured to be turned off by a response signal from the PTS acquisition circuit 42.

In the above embodiment, the first PTS
Even if a data error occurs, the PTS is not used and a clean PTS having no error is used, so that the reliability of the system can be improved.

FIG. 5 further shows a time stamp processing unit 28.
It is another embodiment of. This embodiment is configured to capture the PTS when the system is packet synchronized and there are no error flags. To this end, a further switch 45 is provided in series with the switch 44, and both switches 44, 4
The PTS is input to the PTS acquisition circuit 42 when the signal 5 is on.

In the above embodiment, the switch 44 controlled by the error flag may be omitted. According to this embodiment, the following processing can be performed. That is, in the state where the output permission of the audio decoder 27 is maintained, when the asynchronous determination signal is output from the signal processing unit that detects the frame synchronization of the reproduction code string, the PTS is fetched again and the output timing is changed. Can be accurate.

FIG. 6 shows the configuration of the synchronous / asynchronous determination signal output circuit. This synchronous / asynchronous determination signal output circuit is included in the signal processing 22, for example. The packet data is input to the sync signal detection circuit 46. Sync signal detection circuit 4
6 detects a synchronization signal in the packet data and gives the detection signal to the window circuit 47. Then, the window circuit 47 outputs a window pulse having a pulse width of a fixed period in synchronization with the detection signal, and the window pulse is input to the synchronization detection circuit 48. Sync detection circuit 4
Reference numeral 8 outputs a synchronization determination signal when a synchronization signal is present in the window pulse and this relationship continues repeatedly a plurality of times, and outputs an asynchronous determination signal when such a relationship disappears. To do.

FIG. 7 shows another embodiment of the time stamp processing unit 28. This embodiment is shown in FIG.
The difference from the configuration of FIG. 2 is that a switch 51 is provided on the output line of the comparator 43, and the switch 51 is a PTS.
The output timing control signal which is controlled by the on / off control signal and is supplied to the buffer unit 31 is defined.

As the PTS on / off control signal, the above-described error flag or asynchronous detection signal is used. FIG. 8 is another embodiment of the time stamp processing unit 28.

In the above-described embodiment, the coincidence signal is output when the count content of the time stamp counter 41 and the content of the presentation time stamp included in the voice code packet match, but within a certain allowable range. If so, the output timing control signal may be output to the buffer unit 31. This is because the image and the sound do not exactly match with each other, and even if there is a slight deviation, the viewer does not feel that strange.

In FIG. 8, the output of the PTS acquisition circuit 42 is input to one of the subtraction circuits 51. The count value from the time stamp counter 41 is supplied to the other input of the subtraction circuit 51. Difference data (AB) between the PTS and the count value is obtained from the subtraction circuit 51, and this difference data is input to the difference data processing unit 52. The difference data processing unit 52 outputs the output timing control signal to the buffer unit 31 if the difference is within a predetermined allowable range. If the difference is outside the allowable range, the information can be given to, for example, the clock control unit, the servo control unit, or the warning display unit.

If it is out of the allowable range, the next PTS
The PTS acquisition circuit 42 is controlled so as to acquire, and if the difference is within a predetermined range, the PT to the PTS acquisition circuit 42 is acquired.
S uptake is restricted.

FIG. 9 shows another embodiment of the time stamp processing unit 28. In this embodiment, P
The comparator 52 that compares the value A of the TS with the output count value B of the counter unit 41 is configured to obtain the determination outputs of A = B and A <B. All of these judgment outputs are input to the OR circuit 53, and the output of the OR circuit 53 is given to the buffer unit 31 as an output timing control signal. Therefore, when the PTS value A is small, that is, when the audio decoding is delayed with respect to the video, the audio signal is output. Further, the determination output of A <B is supplied to, for example, a servo microcomputer or a system control unit to notify the current state of A <B. The information of A <B can be used, for example, to control the read clock frequency of the decoded audio data.

In the above description, the input information is described as being reproduced from the optical disc, but the signal source of the input information is not limited to this, and it is sent via a communication line or a transmission line. You can use the information you received.

FIG. 10 shows another embodiment of the present invention. In the above-described embodiment, the switching 44 and 45 are directly controlled by the error flag and the asynchronous detection signal. However, one switching 44 on the input side of the PTS acquisition circuit 42 may be controlled based on the switch control signal from the system controller 33.

The system controller 33 turns off the switch 44 when an error flag or an asynchronous determination signal is input. Then, when there is no error flag and there is no asynchronous determination signal (the synchronization determination signal is input), the switch 44 is turned on for a certain period (a period in which PTS can be captured), and thereafter, the match signal (A = B) or a difference signal within a predetermined range is obtained, the switch 44 is turned off.

FIG. 12 shows the system controller 3 described above.
3 is an example of a flowchart stored in FIG. When the reproduction is started, data is taken in and it is judged that there is no error flag and that there is no asynchronous judgment signal (steps A1 to A3). If there is no error flag or asynchronous determination signal, it is determined whether A = B has already been obtained (step A4). This corresponds to the determination as to whether it is the first PTS. If A = B is not obtained, the switch 44 is turned on in step A5, and A
= B is obtained (steps A5 and A6).
When A = B is obtained, switch 44 is turned off, and step A
Return to 2. As a result, the data is reproduced with the synchronous processing using the PTS turned off, but when the asynchronous determination signal is generated, the synchronous processing is performed again from the time when the asynchronous determination signal disappears.

FIG. 11 shows the system controller 3 described above.
6 is still another example of the flowchart stored in FIG. The difference from the flowchart of FIG. 10 is that step A8 for determining whether or not a set time has elapsed is provided on the route returning from step A4 to step A2. By providing this step A8, it is possible to redo the synchronization process using the PTS every time a certain time has elapsed. That is, if the set time has elapsed in step A8, the set time is reset (step A
9) After step A5, the PTS is retaken again. As the set time, the viewer can select and input an arbitrary time through the remote controller and the microcomputer. In this way, synchronization is re-acquired every set time.

Of course, in the above system, the optical disc on which the moving image and the music are recorded may be reproduced. Therefore, it is possible to always turn on the switch 44 so that the synchronous processing is always performed. Is.

[0040]

As described above, according to the present invention, when a video code string and an audio code string are respectively decoded and output, the output timing of the audio signal is synchronized with the video signal as accurately as possible with a simple circuit configuration. Can be made.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an optical disc reproducing apparatus to which the present invention is applied.

FIG. 2 is an explanatory diagram of a reproduction code string reproduced from an optical disc.

FIG. 3 is a diagram showing a configuration example of a time stamp processing unit in FIG.

FIG. 4 is a diagram showing another configuration example of the time stamp processing unit in FIG.

FIG. 5 is a diagram showing another configuration example of the time stamp processing unit of FIG. 1.

FIG. 6 is a diagram showing a configuration example of a synchronous / asynchronous determination signal output circuit.

FIG. 7 is a diagram showing another configuration example of the time stamp processing unit of FIG. 1.

FIG. 8 is a diagram showing still another configuration example of the time stamp processing unit of FIG. 1.

FIG. 9 is a diagram showing another configuration example of the time stamp processing unit of FIG. 1.

10 is a diagram showing another configuration example of the time stamp processing unit in FIG.

11 is a flowchart showing an operation example of the system controller shown in FIG.

12 is a flowchart showing another operation example of the system controller shown in FIG.

[Explanation of symbols]

11 ... Optical disc, 12 ... Motor, 21 ... Optical pickup device, 22 ... Signal processing unit, 25 ... Demultiplexer, 26 ... Video decoder, 27 ... Audio decoder, 28 ... Time stamp processing unit, 29, 31 ... Buffer Part, 41 ... Time stamp counter part, 42 ... PT
S capture circuit, 43 ... Comparator, 44, 45 ... Switch,
51 ... Switch, 52 ... Comparator, 53 ... OR circuit.

Claims (9)

[Claims] 1. A presentation time stamp (hereinafter referred to as PTS) as time information for synchronizing a video and audio in a specific packet of a data compressed video code string and each packet of a data compressed audio code string. Is described, and is a device to which a reproduction code sequence is sent in which the video code sequence and the audio code sequence are transmitted in a time division manner, and a video which captures and decodes the video code sequence. A decoder section, an audio decoder section for taking in and decoding the voice code sequence, a time stamp counter means for counting a reference clock in synchronization with a predetermined reproduction timing of the reproduction code sequence, and the PTS included in the voice code sequence. Take in this P
A means for determining the relationship between the contents of TS and the count value of the time stamp counter means, and when the PTS and the count value have a predetermined relationship first, an output timing control signal of the audio decoder section is output. Output,
A synchronizing device for a video / audio processing device, comprising: PTS control means for maintaining audio output permission thereafter. 2. The PTS control means prohibits the PTS acquisition when an error flag is present from a signal processing unit which performs error correction of the reproduction code sequence, and prohibits the PTS acquisition when there is no error flag. The synchronizing device of the video / audio processing device according to claim 1, wherein 3. The PTS control means, when an asynchronous determination signal is output from a signal processing unit which detects frame synchronization of the reproduction code sequence, the PT control means.
2. The synchronizing apparatus for a video / audio processing apparatus according to claim 1, wherein the STS is prohibited from being taken in, and the PTS is taken in when a synchronization determination signal is present. 4. The PTS control means fetches the PTS when any one of an error flag and an asynchronous determination signal from a signal processing unit for detecting error correction and frame synchronization of the reproduction code string is present. 2. The synchronizing apparatus of the video / audio processing apparatus according to claim 1, wherein the PTS is fetched when both the error flag and the asynchronous determination signal are absent. 5. The PTS control means outputs an asynchronous determination signal from a signal processing unit that detects frame synchronization of the reproduction code string in a state where output permission of the audio decoder unit is maintained. 2. The synchronizing device for a video / audio processing apparatus according to claim 1, further comprising means for re-taking in the PTS again. 6. The PTS control means determines whether or not the contents of the PTS and the count value match in order to determine the predetermined relationship between the PTS and the count value, and when they match, the output timing control. The synchronizing device of the video / audio processing device according to claim 1, wherein the synchronizing device outputs a signal. 7. The PTS control means determines whether the difference between the PTS and the count value is within a predetermined range to determine the predetermined relationship between the PTS and the count value. 2. The synchronizing device for a video / audio processing apparatus according to claim 1, wherein the output timing control signal is output to. 8. The video according to claim 7, wherein the PTS control means outputs information indicating which of the PTS and the count value is larger and outputs the information to the system control section. Synchronizer for audio processing equipment. 9. The PTS control means compares a PTS loading circuit for loading the PTS included in the voice code string with a PTS loaded in the PTS loading circuit and a count value of the time stamp counter means. And a comparator that obtains a judgment output of whether or not they match, when an error flag and / or an asynchronous judgment signal is given from the signal processing unit that is provided in the output unit of the comparator and that processes the reproduction code string. 2. The synchronizing device for a video / audio processing apparatus according to claim 1, further comprising a switch that is turned off to prohibit the determination output from being supplied to the output control unit of the audio decoder.