JP2002027413A - Digital video reproducing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system which allows synchronous reproduction at restart of reproduction even after a suspension for synchronous reproduction with a plurality of digital video reproduction systems which reproduce a disc where MPEG data are recorded. SOLUTION: Reproducing systems A and B constituting a digital video reproduction system comprises counters 106 and 116 as well as communication parts 107 and 117. Here, the number of data outputted up to where it is convenient after receiving suspension instruction is counted with the counters 106 and 116, respectively, and the count values are transmitted mutually to other reproduction systems, each other, through the communication parts 107 and 117. At restart of the reproduction, a minimum value is selected out of its own count values as well as out of the count values transmitted from other reproduction system, respectively, at each reproduction system, and then the minimum value is subtracted from its own value. The output of data from a data buffer is delayed by the resulting value for synchronous reproduction even at restart of reproduction after suspension.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital video reproducing apparatus for reproducing digitally encoded video and audio signals, and more particularly to a digital video reproducing apparatus for simultaneously operating a plurality of reproducing apparatuses.

[0002]

2. Description of the Related Art In a conventional analog baseband disk system, when reproducing a video / audio signal recorded on a disk, a time for reading data corresponding to one frame is always constant. In such a case, it is very difficult to synchronize a plurality of video reproducing apparatuses that reproduce a two-dimensional image with each other by synchronizing and reading at a constant speed an optical disk or the like on which video and audio signals are recorded. That was not the case. For example, in the related art, a stereoscopic video has been obtained by synchronizing a video reproduction device that reproduces image data for the right eye and a video reproduction device that reproduces image data for the left eye using a synchronization signal.

On the other hand, MPEG (Moving Picture Coding Experts Group), which is an international standard for moving picture data compression, is used.
In p), the amount of image data is compressed by employing predictive coding and unequal length coding. The predictive coding includes a method using correlation between pixels in a frame and a method using correlation between frames. FIG. 3 shows a method utilizing correlation between frames among these methods. In the figure, I indicates an I picture, and the I picture is an image compressed without using the correlation between frames. P indicates a P picture,
This is obtained by compressing using a temporally previous I picture or P picture as a predicted image. Further, B is a B picture, which is obtained by compressing a temporally earlier I picture or P picture and a temporally later I picture or P picture as predicted images.

FIG. 4 shows the structure of a sequence in MPEG. One sequence has a sequence header at the beginning, and a plurality of GOPs (Group Of) following the sequence header.
Picture). This GOP is composed of a plurality of pictures starting with an I picture. In order to apply an encoded video or audio stream compressed by MPEG to an actual application, the stream is integrated into a single unit including synchronization, and the stream is stored in a unique physical device such as a storage medium or network. The data format must be compatible with the format and protocol. The role of the MPEG system is to synchronize and multiplex data such as video and audio data.

[0005] MPEG video and audio data are multiplexed by packets. Multiplexing by packets is a method of dividing video and audio data into streams of an appropriate length called packets, attaching additional information such as a header, switching video / audio packets, and performing time division transfer. is there. FIG. 5 shows a PES (Passive) of MPEG2 which is one of the MPEG standards.
cketized Elementary Stream) packet. The video or audio data stream is divided, added with a header as shown in the figure, and stored in the packet data section. The MPEG2 transport stream is multiplexed with 188-byte fixed-length transport packets. FIG. 6 shows the data structure of an MPEG2 transport packet. Here, the PES packet shown in FIG. 5 is divided into payloads.

[0006] In the MPEG system, information indicating when video and audio data should be decoded and reproduced by a decoder is added. That is, in FIG. 5, DTS (Decoding Time Stamp) indicates a decoding time, and PTS (Presentation Time Stamp) indicates a reproduction output time. In addition, in the adaptation field of the transport packet shown in FIG.
ogram Clock Reference). PCR
Is to set a reference time to a decoder (not shown). That is, when receiving the PCR, the decoder sets the time of the internal clock of the decoder to the value of the PCR, and the time is set to DT.
When it becomes S, decoding is performed, and when it becomes PTS, reproduction output is executed.

FIG. 2 is a block diagram showing a configuration of a conventional digital video reproducing apparatus which outputs data compressed by MPEG using an optical disk as a recording medium. As shown in the figure, the digital video playback device uses MPEG
201 on which the data compressed by
And a disk reading unit 203 that reads data from the disk, a data buffer 205 that holds temporary data to control the flow of data and outputs the data to the outside, and a command that receives a command to start or pause playback from the outside. It comprises a receiving unit 204 and a controller 202 which controls the disk reading unit 203 and the data buffer 205 in response to an external command.

In the above configuration, when the command receiving section 204 receives a reproduction command, the command is transmitted to the controller 202. When the controller 202 receives the reproduction instruction, the disk reading unit 203
To play. As a result, the disk reading unit 203 reads data from the disk 201, and the read data is stored in the data buffer 205. Then, when the controller 202 instructs the data buffer 205 to output data, image data is output.
The output image data is decoded by a decoder (not shown), and is finally reproduced as a video on a display device such as a TV monitor or a liquid crystal projector.

Next, when the command receiving unit 204 receives a pause command during data reproduction and the command is transmitted to the controller 202, the controller 202 instructs the disk reading unit 203 to temporarily stop reading the disk. This instructs the data buffer 205 to stop outputting data. However, if the output is stopped in the middle of the data, only the data of a part of the picture is output, so that it may be impossible to normally reconstruct the MPEG stream on the data receiving side. Therefore, the controller 202 instructs the disk reading unit 203 and the data buffer 205 to output data where the data is well-divided, for example, to the end of the picture data being output or to the end of the GOP being output. When the pause is resumed, the output is started from a new picture or GOP data.

[0010]

There is no problem in operating the conventional digital video reproducing apparatus configured as described above alone. However, in the case where a plurality of digital video playback devices are composed of a plurality of playback devices and these playback devices are played back in synchronization (one screen is composed of images from the plurality of playback devices, There are various cases such as a case where the image data and the left-eye image data are reproduced simultaneously to reproduce a three-dimensional video), and the following problem occurs.

FIG. 7 shows a case in which image data is output from two reproduction apparatuses, reproduction apparatus A and reproduction apparatus B. When the pause is instructed at the time T, the reproducing device A outputs data until the time T1, while the reproducing device B outputs data until the time T2, and the respective devices are in a pause state. Then, when an instruction to release the pause and resume the reproduction is given, the reproducing apparatus A restarts the output from the data to be output at the time T1, and the reproducing apparatus B outputs the data at the time T2. Output will be restarted from the data.

However, the decoder receiving the image data from the reproducing apparatus A sets the time at which the data is input to T1, and the decoder receiving the image data from the reproducing apparatus B sets the time at which the data is input to T2. Because it will be set,
As a result, a time lag occurs between the two decoders, and the reproduced images may not be synchronized.

[0013]

According to the present invention, there is provided a digital video reproducing apparatus comprising a plurality of reproducing apparatuses for reproducing a recording medium on which digital video / audio signal data is recorded. The apparatus comprises: an output data amount integrating means for integrating the amount of data output from a point in time when the pause of reproduction is instructed to the end of a predetermined unit; and an integrated value for mutually transmitting and receiving the integrated value in the output data amount integrating means Transmitting / receiving means, and control means for delaying output of data when the pause is released and reproduction is resumed based on the integrated value of the output data amount integrating means and the integrated value from the integrated value transmitting / receiving means. It is characterized by having.

Further, the present invention is a digital video reproducing apparatus comprising a plurality of reproducing apparatuses for reproducing a recording medium on which digital video / audio signal data is recorded, wherein each reproducing apparatus is instructed to pause reproduction. Output data amount integrating means for integrating the amount of data output from a point in time to the end of a predetermined unit; integrated value transmitting and receiving means for mutually transmitting and receiving the integrated value in the output data amount integrating means; and The smallest value among the integrated value and the integrated value from the integrated value transmitting / receiving means is selected, and the difference between the integrated value of the output data amount integrating means and the selected value is obtained. Control means for delaying the output of data by the difference when restarting.

Further, the present invention is a digital video reproducing apparatus comprising a plurality of reproducing apparatuses for reproducing a recording medium on which digital video / audio signal data is recorded, wherein each reproducing apparatus is instructed to pause reproduction. Output time integrating means for integrating the time required to output data from the time to the end of a predetermined unit; integrated value transmitting and receiving means for mutually transmitting and receiving the integrated value in the output time integrating means; and A control means for delaying the output of data when the pause is released and the reproduction is resumed based on the integrated value and the integrated value from the integrated value transmitting / receiving means.

The present invention also relates to a digital video reproducing apparatus comprising a plurality of reproducing apparatuses for reproducing a recording medium on which digital video / audio signal data is recorded, wherein each reproducing apparatus is instructed to pause reproduction. Output time integrating means for integrating the time required to output data from a point in time to the end of a predetermined unit; integrated value transmitting and receiving means for mutually transmitting and receiving the integrated value in the output time integrating means; and output data amount integrating means. Of the integrated value and the integrated value from the integrated value transmitting / receiving means, and the difference between the integrated value of the output data amount integrating means and the selected value is obtained. And control means for delaying the output of data by the difference when restarting.

The present invention also provides a digital video reproducing apparatus comprising a plurality of reproducing apparatuses for reproducing a recording medium on which digital video / audio signal data is recorded, and a control apparatus for controlling the plurality of reproducing apparatuses. The playback device is an output data amount integration unit that integrates the amount of data output from a point in time when a pause of playback is instructed to the end of a predetermined unit,
Integrated value transmitting means for transmitting the integrated value in the output data amount integrating means to the control device, wherein the control device cancels the pause and resumes playback of each playback device, Synchronous control means for synchronizing by varying the time until the reproduction of each reproduction apparatus is restarted based on the integrated value received from the apparatus.

The present invention also relates to a digital video playback apparatus comprising a plurality of playback devices for playing back a recording medium on which digital video / audio signal data is recorded, and a control device for controlling the plurality of playback devices. The playback device includes an output time integration unit that integrates a time required to output data from a point in time when a pause of playback is instructed to the end of a predetermined unit, and an integrated value in the output time integration unit to the control device. An integrated value transmitting means for transmitting, the control device, when the pause is released and the reproduction of each reproduction device is restarted, based on the integrated value received from each of the reproduction devices, Synchronization control means for synchronizing by varying the time until the reproduction is restarted is provided.

Further, according to the present invention, the digital video / audio signal is compressed by predictive coding and unequal length coding. Further, in the present invention, the digital video / audio signal data is compressed by an MPEG system. In the present invention, the predetermined unit is any one of an I picture, a P picture, a B picture, a GOP (Group Of Picture), and a sequence in digital video / audio signal data compressed by the MPEG system. .

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an example of a digital video reproducing apparatus according to the present invention.
And a playback device B, a digital video playback device is constituted. The reproducing apparatus A includes a disk 101 (the disk 111 in the reproducing apparatus B) on which data compressed by MPEG is recorded, a disk reading unit 103 for reading data from the disk (a disk reading unit 113 in the reproducing apparatus B), Buffer 105 (the data buffer 115 in the case of the playback device B) for holding temporary data and outputting the data to the outside, and a command receiving unit 104 (for the playback device) for receiving commands such as playback start and pause from the outside. In B, the command receiving unit 1
14) and a controller 102 (in the reproducing apparatus B, the controller 11) for controlling the disk reading unit 103 (and the disk reading unit 113) and the data buffer 105 (and the data buffer 115) by an external command.
2), a counter 106 for counting the number of data outputs (the counter 116 in the reproducing apparatus B), and a communication unit 107 for exchanging information with another reproducing apparatus (the communication unit 117 in the reproducing apparatus B). It is configured.

In the above, various commands such as a command for starting reproduction and a pause may be considered, such as a signal from a remote control device such as an infrared remote controller or a signal from a separately provided main control device. Also, the playback device A and the playback device B
Are decoded by a decoder (not shown). Next, the operation of the digital video playback device of the present invention configured as described above will be described.

<1. From Stopped State to Playback> First, when a command for instructing playback is given to the playback apparatus A and the playback apparatus B by an infrared remote controller or the like, the command reception unit 104 and the command reception unit 114 receive the command. 102 and the controller 112. The controller 102 and the controller 112 which have received the reproduction instruction instruct the disk reading unit 103 and the disk reading unit 113 to reproduce the disks 101 and 111.

The controller 102 and the controller 11
The disk reading unit 103 and the disk reading unit 113 receiving the reproduction instruction from the disk 101 and the disk 1
By driving various servos such as a focus servo, a tracking servo, and a spindle servo to an active state, and when it becomes possible to read data from the disk, it informs the controller 102 and the controller 112 to that effect. The controller 102 and the controller 112 that have received the command communicate with the communication unit 107 and the communication unit 11.
7, the other digital video playback devices are notified that data can be read from the disk.

In response to this notification, the controller 102 and the controller 112 make the disk reading unit 103 and the disk reading unit 113
Data is read from the data buffer 1 and the read data is stored in the data buffer 105 and the data buffer 115. Then, the controller 102 and the controller 11
2 instructs the data buffer 105 and the data buffer 115 to output data, so that each digital video playback device outputs image data. The output image data is decoded by a decoder (not shown), and is finally displayed as an image on a display device such as a TV monitor or a liquid crystal projector.

As described above, the two playback devices notify each other of the digital video playback devices that the data can be read from the disk, and upon receiving this notification, each playback device sends Since playback starts synchronously,
The image projected on the display device does not shift in time. <2. From Reproduction State to Pause> Next, the operation from the reproduction state to the pause reproduction state will be described.
In FIG. 7, for example, when a pause instruction is given to each of the playback devices at time T, the playback device A outputs data up to a point where data is well separated, that is, the playback device A until time T1, and the playback device B outputs Data is output until time T2. In this example, the output is performed until the end of the picture. However, the output may be performed until the end of the GOP or the end of the sequence.

When the pause instruction is given from the reproduction state as described above, the output of the data is performed in parallel with the output of the data.
The number of data output after receiving the temporary stop instruction is counted by the counter 106 and the counter 116. Then, after the output of data in each playback device is completed, the controller 102 reads the count value X of the counter 106, and the playback device A transmits the count value X to the playback device B from the communication unit 107, B is received via the communication unit 117.

On the other hand, the reproducing apparatus B is also
Reads the count value Y of the counter 116 and transmits the count value Y to the playback device A from the communication unit 117, and the playback device A receives this via the communication unit 107. In this way, the playback devices transmit and receive the count value of the number of data output after receiving the pause instruction. <3. From the paused state to the reproduction> When a command instructing the release of the pause or the resumption of the reproduction is given to both the reproduction apparatuses, the controller 102 of the reproduction apparatus A and the other reproduction apparatus (the reproduction apparatus B) The smallest value is selected from the count value Y sent from the server. In this example, since the count value X> the count value Y, the count value Y is selected. Then, the count value Y is subtracted from the count value X of the own device, the output of data from the data buffer 105 is delayed by the difference, and the output of data is restarted.

On the other hand, in the reproducing apparatus B, the controller 11
2 selects the minimum value from its own count value Y and the count value X sent from another reproducing apparatus (reproducing apparatus A). In this example, the count value Y is selected. Then, the count value Y is subtracted from the own count value Y, and the output of data from the data buffer 115 is delayed by the difference. However, since the own value is Y, Y−Y = 0, and therefore, no delay is caused. Data output from the data buffer 115 is restarted.

As described above, after the reproducing apparatus B restarts the data output, the reproducing apparatus A restarts the data output after delaying by the time corresponding to the difference between the count value X and the count value Y. The delay of the data amount corresponding to the difference between the count value X and the count value Y is temporally equivalent to the difference between the time T1 and the time T2. You can take it.

The values transmitted from the communication unit 107 and the communication unit 117 can be determined from the difference in the amount of data output from each playback device after receiving the pause instruction.
Instead of the data number, time information (time T1-time T,
Time T2-time T) is also possible. In this case as well, the minimum value (time information) is selected in the same manner as described above, the value is subtracted from the own value, and the data output is delayed by this time.

In the above example, the digital video playback device is composed of two playback devices. However, the present invention is not limited to this, and the digital video playback device may be composed of more playback devices. Further, as shown in FIG. 8, it is conceivable to configure a digital video playback device with a plurality of playback devices (A to D) and a main control device. In this case, each playback device transmits the above-described integrated value to the main control device, and the main control device that has received the integrated value calculates the above-described delay time for each playback device, cancels the pause, and plays back each playback device. Is resumed (each playback device is in a paused state until a command to release the pause is received from the main control device), the time until the playback of each playback device is resumed (until the restart command is transmitted). Time). This makes it possible to synchronize the data output of each playback device after the playback is resumed. In the above embodiment, each playback device transmits and receives the integrated value to and from each other, calculates the delay time in each playback device, and further controls the delay based on the calculation result by itself. As the number increases, the interconnection between the devices becomes more difficult. However, in the configuration of this embodiment, the calculation of the integrated value is performed by each playback device. However, since it is the main control device that receives each integrated value and calculates the delay time for each device, each playback device Is simply connected to the main control device, and there is an advantage that the main control device can also collectively control the playback devices.

[0032]

As described above, according to the present invention, M
When synchronized playback is performed by a plurality of digital video playback devices that play back a disk on which video and audio data compressed by PEG and other predictive encoding and unequal length encoding are recorded, playback after pause is performed. Playback can be performed synchronously even when resuming.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a digital video playback device according to the present invention.

FIG. 2 is a block diagram illustrating a configuration of a conventional digital video playback device.

FIG. 3 shows an I picture, a P picture, and a B picture in MEPG.
FIG. 3 is a diagram illustrating a relationship between pictures.

FIG. 4 is a diagram showing a sequence configuration in MPEG.

FIG. 5 is a diagram showing a configuration of a PES packet in MPEG2.

FIG. 6 is a diagram showing a configuration of a transport packet in MPEG2.

FIG. 7 is a diagram for explaining operations of the digital video playback device of the present invention and a conventional digital video playback device.

FIG. 8 is a block diagram illustrating a configuration of a digital video playback device according to another embodiment of the present invention.

[Explanation of symbols]

 101, 111 disk 102, 112 controller 103, 113 disk reading unit 104, 114 command receiving unit 105, 115 data buffer 106, 116 counter 107, 117 communication unit

Claims (9)

[Claims] 1. A digital video playback device comprising a plurality of playback devices for playing back a recording medium on which digital video / audio signal data is recorded, wherein each of the playback devices is provided with a predetermined time from a point in time when a pause of playback is instructed. Output data amount integrating means for integrating the amount of data output up to the end of the unit, integrated value transmitting and receiving means for mutually transmitting and receiving the integrated value in the output data amount integrating means, and an integrated value of the output data amount integrating means A digital video playback device comprising: a control unit that delays data output when the pause is released and the reproduction is resumed based on the integration value from the integration value transmission / reception unit. 2. A digital video reproducing apparatus comprising a plurality of reproducing apparatuses for reproducing a recording medium on which digital video / audio signal data is recorded, wherein each of the reproducing apparatuses has a predetermined time from a point in time when a pause of reproduction is instructed. Output data amount integrating means for integrating the amount of data output up to the end of the unit, integrated value transmitting and receiving means for mutually transmitting and receiving the integrated value in the output data amount integrating means, integrated value of the output data amount integrating means and When the smallest value is selected from the integrated values from the integrated value transmitting / receiving means and the difference between the integrated value of the output data amount integrating means and the selected value is obtained, the pause is released to resume reproduction. And a control means for delaying the output of data by the difference. 3. A digital video playback device comprising a plurality of playback devices for playing back a recording medium on which digital video / audio signal data is recorded, wherein each of the playback devices has a predetermined length of time from a point in time when a pause of playback is instructed. Output time integrating means for integrating the time required to output data to the end of the unit, integrated value transmitting and receiving means for mutually transmitting and receiving the integrated value in the output time integrating means, and an integrated value of the output time integrating means. A digital video playback device comprising: a control unit that delays data output when the pause is released and the reproduction is resumed based on the integration value from the integration value transmission / reception unit. 4. A digital video reproducing apparatus comprising a plurality of reproducing apparatuses for reproducing a recording medium on which digital video / audio signal data is recorded, wherein each of the reproducing apparatuses has a predetermined length of time from a point in time when a pause of reproduction is instructed. Output time integrating means for integrating the time required to output data up to the end of the unit, integrated value transmitting and receiving means for mutually transmitting and receiving the integrated value in the output time integrating means, and integrated value of the output data amount integrating means And selecting the minimum value among the integrated values from the integrated value transmitting / receiving means, obtaining the difference between the integrated value of the output data amount integrating means and the selected value, releasing the pause and restarting the reproduction. Control means for delaying the output of data by an amount corresponding to the difference. 5. A digital video playback apparatus comprising: a plurality of playback devices for playing back a recording medium on which digital video / audio signal data is recorded; and a control device for controlling the plurality of playback devices. Output data amount integrating means for integrating the amount of data output from the point in time when the pause of reproduction is instructed to the end of a predetermined unit, and an integrated value transmission for transmitting the integrated value in the output data amount integrating means to the control device Means, the control device, when releasing the pause and restarting the playback of each playback device, based on the integrated value received from each playback device,
A digital video playback device comprising: a synchronization control unit that synchronizes the playback devices with different times until the playback is restarted. 6. A digital video playback device comprising a plurality of playback devices for playing back a recording medium on which digital video / audio signal data is recorded and a control device for controlling the plurality of playback devices, wherein each of the playback devices comprises: Output time integrating means for integrating the time required to output data from the point in time when the pause of reproduction is instructed to the end of a predetermined unit, and an integrated value for transmitting the integrated value in the output time integrating means to the control device When the control device releases the pause and resumes playback of each playback device, based on the integrated value received from each playback device,
A digital video playback device comprising: a synchronization control unit that synchronizes the playback devices with different times until the playback is restarted. 7. The digital video reproducing apparatus according to claim 1, wherein said digital video / audio signal data is compressed by predictive encoding and unequal length encoding. 8. The digital video / audio signal data is MP
8. The digital video reproducing apparatus according to claim 1, wherein the digital video reproducing apparatus is compressed by an EG method. 9. The I / P picture in digital video / audio signal data compressed by the MPEG system,
P picture, B picture, GOP (Group OfPictur)
7. The digital video reproducing apparatus according to claim 1, wherein the digital video reproducing apparatus is any one of e) and a sequence.