JP2001268517A - Digital video reproduction system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital video reproduction system capable of synchronously operating digital encoded data such as MPEG by plural reproducing devices. SOLUTION: A master reproducing device 10#1 outputs a data sending reference clock DSCLK and a data decoding reference clock DDCLK to respective slave reproducing devices 10#2 to 10#N. The clock DSCLK is a reference to be sent to a decoding part by respective reproducing devices. On the other hand, the clock DDCLK is a reference for decoding the MPEG data by decoding parts in respective reproducing devices. The master reproducing device 10#1 instructs respective slave reproducing devices 10#2 to 10#N to simultaneously start decoding processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital video playback system for playing back digitally encoded video and audio signals, and more particularly, to a digital video playback system for operating a plurality of playback devices simultaneously in synchronization. About.

[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.

When a plurality of video reproducing apparatuses for reproducing two-dimensional images by themselves are operated in synchronization, in such a case, an optical disk or the like on which a video / audio signal is recorded can be read out by synchronizing at a constant speed. It was not too difficult. 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.

[0004]

In recent years, digital compression techniques for image data have been developed, and recording and transmission of image data has been mainly performed digitally. The MPEG2 method is a typical example of a method for encoding a moving image. In a digital encoding method such as MPEG2,
The data amount differs for each frame. That is, since the amount of data per frame differs depending on the pattern and movement of the image, the time read from the data recorded on the optical disk or the like differs. In MPEG2, when a high-definition image is transferred or a plurality of programs such as broadcast stations are multiplexed and transferred, a transport stream (TS: Transp) is used.
ort Stream) method is used. The TS is for time-division multiplexing data in a relatively short transmission unit called a transport packet. The TS data before decoding includes time management information for decoding and reproducing processing called a time stamp. The time stamp includes time management information (PTS: Presentation Time Stamp) of the reproduction output.
And decoding time management information (DTS: Decoding Time Stam).
p), and the two types of time stamps are T
It is included in the S data.

[0005] The decoding section of the video reproduction apparatus reproduces the moving image by reproducing the time information when the video / audio signal is encoded, based on the time management information contained in the TS.

[0006] Therefore, it is not simple to perform a reproducing process by synchronizing a plurality of video reproducing devices for reproducing digitally encoded video and audio signals. There is a need for a synchronous playback mechanism adapted to a system for playing back such digitally compressed data.

An object of the present invention is to provide a digital video reproducing system capable of synchronously reproducing a plurality of video reproducing apparatuses for reproducing video and audio signals compressed and encoded by a digital system such as MPEG. That is.

[0008]

According to the present invention, there is provided a digital video reproducing system for synchronously reproducing digitally encoded video and audio signals on two or more channels,
A first playback unit that plays back the first video and audio signals;
The first reproducing means includes first storing means for holding digitally encoded first data corresponding to the first video and audio signal, and temporarily receiving the first data from the first storing means. First data sending means for sending the data together with the first transfer clock, first reference clock generating means for generating a data sending reference clock that is a reference for the first transfer clock, and first data First decoding means for receiving and decoding the first data and the first transfer clock from the sending means, and second reference clock generating means for generating a decoding reference clock serving as a reference for decoding of the first decoding means; And further comprising a second playback device for playing back the second video / audio signal, wherein the second playback device comprises a second playback device.
Storage means for holding digitally encoded second data corresponding to the video and audio signals of the first and second types, and receiving and temporarily storing the second data from the second storage means; Second data transmission means for generating a second transfer clock synchronized with the first transfer clock in response to the second transfer clock, and transmitting the second transfer clock along with the second data;
Second decoding means for receiving the second data and the second transfer clock from the second data transmission means and decoding the second data in accordance with the transfer clock and the decode reference clock.

Preferably, the first reproducing apparatus further includes timing control means for controlling timings at which the first and second data transmission means transmit the first and second data, respectively, wherein the timing control means comprises: At the start of the synchronized playback of the first and second video / audio signals, the first and second data sending means wait until both are ready for sending, and then the first and second data sending means are ready.
Are instructed to simultaneously output the first and second data, respectively.

Preferably, the digital video reproduction system further includes a synchronous coupling means for adjusting the timing so that the outputs of the first and second decoding means coincide with a phase corresponding to the external synchronization signal.

[0011] Preferably, the first data is subjected to a plurality of first screen data corresponding to a plurality of screens to be subjected to intra-screen compression and to a predictive encoding using the plurality of first screen data. And a plurality of second screen data respectively corresponding to a plurality of screens corresponding to the plurality of screens to be subjected to intra-screen compression. A plurality of fourth screen data respectively corresponding to a plurality of screens to be subjected to predictive encoding using the third screen data, wherein the first storage means stores the first screen data as the first data The third screen data reproduced corresponding to the time transmitted from the transmitting means and the first screen data is the second screen data.
Holding the index data indicating the correspondence with the time sent from the data sending means, and the first reproducing means refers to the index data when receiving the instruction to temporarily stop the first and second data. Control means for instructing the sending unit to stop sending data is further included.

[0012] More preferably, the index data is:
The correspondence between the third screen to be transmitted from the second data transmission means and the first screen when the first screen is transmitted from the first data transmission means is shown.

More preferably, the digital encoding method is the MPEG2 method, and the first and third data are
This is picture data.

Therefore, according to the present invention, a plurality of digital video reproducing apparatuses using compressed digitally encoded data can be operated synchronously, a two-dimensional image can be reproduced by itself, and a plurality of digital video reproducing apparatuses can be reproduced. A digital video playback system capable of playing back three-dimensional or multi-channel images can be realized.

[0015] Furthermore, synchronous operation can be performed without any problem even during pause or resumption of reproduction.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

FIG. 1 is a block diagram showing the overall configuration of a digital video playback system 1 according to the present invention.

Referring to FIG. 1, a digital video playback system 1 includes a playback device 1 that is a master of a plurality of playback devices.
0 # 1, the reproducing devices 10 # 2 to 10 # N which are simultaneously operated in synchronization with the reproducing device 10 # 1, and the reproducing devices 10 # 1 to 10 # 1 to
The video and audio signals OUT1 to OUTN are received from 10♯N and the horizontal synchronization signal Hsync and the vertical synchronization signal Vsync are received.
And a GEN-Lock unit 12 that finely adjusts the timing and outputs the video / audio output signals AVOUT1 to AVOUTN to the display device. GEN-Lock
Is also called synchronous coupling (generator locking).

The playback device 10 # 1 has the playback devices 10 # 2-
Data decode reference clock DDCL for 10♯N
Output K. The playback device 10 # 1 is the playback device 10 # 2.
By giving a control signal CONTROL to 10 @ N, control such as reproduction and fast-forward / rewind is performed.

The playback device 10 # 1 includes a main control unit 22 described later. In FIG. 1, the control signal CONTR
The bus for transmitting the OL is used to specify data to be reproduced between the master reproduction device and the slave reproduction device and to control the stop of data transmission between the master reproduction device and the slave reproduction device via communication means such as a LAN and RS232C. Is controlled by

Also, the reproducing apparatus 10 # 1 is
Data transmission reference clock DSC for {2-10} N
LK is given. When a certain amount of MPEG data is read from the built-in storage unit when a reproduction start instruction is issued, the slave reproducing devices 10 # 2 to 10 # N prepare the reproducing device 10 # 1 for data transmission to the decoding unit. Are completed, data ready signals DR2 to DRN are output. Accordingly, the playback device 10 # 1 becomes the playback device 10 # 2 to 10 # N.
, Output a send enable signal, that is, send enable signals SE2 to SEN. Then, the playback device 10 # 2
-10 N sends out the data to the built-in MPEG data decoding unit, and the MPEG data decoding unit starts the decoding in response to the video / audio signals OUT2 to OUT
N starts to be output.

FIG. 2 is a block diagram showing a configuration of the reproducing apparatus 10 # 1 shown in FIG. Referring to FIG. 2, playback device 10 # 1 has storage unit 2 in which video and audio signals are stored.
4, an MPEG data transmission unit 30 that receives the MPEG data BTS1 from the storage unit 24, and an MPEG data transmission unit 3
An MPEG data decoding unit 34 receives the data TS1 which is digitally encoded video / audio signal data from 0 and the data transfer clock DCLK1 and decodes the MPEG data. The data TS1 is data composed of the packets of the TS method described above.

The reproduction apparatus 10 # 1 further includes a data transmission reference clock generation section 26 for generating a data transmission reference clock DSCLK which is a reference for the MPEG data transmission section 30 to transmit data, and a state in which data can be transmitted. MPEG-1 data is sent when all the data ready signals are received from the other data reproducing signals DR2 to DRN received from the other reproducing apparatuses 10 # 2 to 10 # N which operate synchronously when receiving the data ready signal DR1 indicating that Send enable signal SE1 instructing section 30 to transmit data
And the other playback devices 10 # 2 to 10 # N
, A data transmission timing control unit 28 that outputs send enable signals SE2 to SEN, and a data decoding reference clock generation unit that generates a data decoding reference clock DDCLK that is a reference clock for the MPEG data decoding unit 34 to perform a decoding process. Unit 32.

The playback device 10 # 1 further transmits and receives index data IDX1 to and from the storage unit 24 for controlling playback start, stop, playback restart, and the like, so that the MPEG data transmission unit 30 and the MPEG data decoding unit And a main control unit 22 for controlling the data transmission timing control unit 28. The main control unit 22 sends a control signal CON to the other playback devices 10 # 2 to 10 # N.
TROL is output to control reproduction start, stop, and reproduction restart.

That is, the main control unit 22 controls the entire system and controls the control signal CONTROL in FIG.
LAN or RS2 represented as a bus carrying L
Through communication means such as 32C, the data to be reproduced is specified between the master reproduction device and the slave reproduction device, and the data transmission stop is controlled.

The storage unit 24 includes a magnetic disk, an optical disk,
It is a recording device such as a semiconductor memory.

The MPEG data transmission unit 30 is provided with a storage unit 24
The MPEG data read from the memory is temporarily stored and transmitted in a predetermined format such as a DVB standard parallel signal. The MPEG data transmission unit 30 has at least two buffers therein and activates a data ready signal DR1 to the data transmission timing control unit 28 when the MPEG data is stored to a predetermined amount. Thereafter, in response to activation of the send enable signal SE1 from the data transmission timing control unit, the MPEG data transmission unit 30 transmits the data TS1 on the data transfer clock.

The MPEG data decoding section 34
The decoder conforms to the standard. The MPEG data decoding unit 34 receives the data TS1 and outputs a video / audio signal OUT1 as a decoding result.

The data transmission reference clock generator 26 is a supply source of a reference clock for data transmission used in the MPEG data transmission units of the master reproduction device and each slave reproduction device. The data transmission reference clock DSCLK is generated according to the bit rate of the transport stream to be transmitted, but this frequency is variable.

The data transmission timing control section 28 receives data ready signals DR1 to DRN indicating that data transmission is ready from the MPEG data transmission sections of the master reproduction apparatus and the slave reproduction apparatuses, and outputs data ready signals of all reproduction systems. When the ready signal is activated, the data transmission enable signal, that is, the send enable signals SE1 to SE1
The SEN is sent to the MPEG data transmission units of all the reproduction systems.

When the data ready signals DR1 to DRN of a plurality of playback devices are activated, the data transmission timing control unit 28 simultaneously activates the send enable signals SE1 to SEN.

At this time, the timing for simultaneously activating the send enable signals is not particularly defined. However, at the time of mounting, the send enable signals are changed with the effective falling or rising of the data transfer clock DCLK1 to take into account propagation delays and the like. Data transmission is performed from each device at the next valid edge of the data transmission clock.

As points to be considered in mounting, various control lines for transmitting the signals DRN and SEN shown in FIG. 1 and clocks DDCLK and DSCLK in order to keep the phase of data transmission in each device within a range. It is important to equalize the wiring lengths of common clock lines and the like for transmitting the signal and eliminate the difference in delay.

Data decode reference clock generator 32
Are the master playback device 10 # 1 and the slave playback device 1
0 # N is a reference clock supply source used in the MPEG data decoding units 34 and 34a. For example, MPE
When using the G2 standard, the reference clock 27M
Hz.

FIG. 3 is a block diagram showing a configuration of the reproducing apparatus 10 # N as a representative of the slave reproducing apparatus shown in FIG.

Referring to FIG. 3, reproducing apparatus 10 # N includes storage unit 24a in which video and audio signals are stored, and storage unit 2a.
4a, which receives MPEG data BTSN from the MPEG data transmitting unit 30a, and data T which is digitally encoded video / audio signal data from the MPEG data transmitting unit 30a.
MPEG receiving SN and data transfer clock DCLKN
An MPEG data decoding unit 34a for decoding data. The data TSN is the TS described above.
This is data composed of packets of the system.

The playback device 10 # N further transmits and receives index data IDXN to and from the storage unit 24a to control playback start / stop, playback restart, and the like, so that the MPEG data transmission unit 30a and the MPEG data decoding unit A main control unit 22a for controlling the unit 34a is included. The main control unit 22 outputs a control signal CONTROL to the master playback device 10 # 1 to control playback start, stop, and playback restart.

The main control unit 22a includes a storage unit 24a, an MPEG data transmission unit 30a, and an MP signal in accordance with a control signal CONTROL output from the main control unit 22 of the playback device 10 # 1.
The EG data decoder 34a is controlled. The MPEG data transmitting section 30a outputs the data TSN and the data transfer clock DCLK1 according to the data transmission reference clock DSCLK generated by the data transmission reference clock generating section 26 included in the playback device 10 # 1. The MPEG data decoder 34a performs a decoding process according to the data decode reference clock DDCLK output from the data decode reference clock generator 32 shown in FIG. 2 and outputs a video / audio signal OUTN.

FIG. 4 is a diagram showing the flow of data when the master playback device 10 # 1 and the slave playback device 10 # N operate in synchronization and data is played back in the playback device.

Referring to FIG. 4, at time t1, FIG.
Is transmitted from the storage unit 24 of the reproducing apparatus 10 # 1 shown in FIG.
The data is accumulated in a buffer in the data transmission unit 30. When the preparation for data transmission is completed, the MPEG data transmission unit 30 activates the data ready signal DR1.

At time t2, the MPE of a fixed data amount is read from the storage unit 24a of the reproducing apparatus 10 # N shown in FIG.
The G data BSTN is transmitted, and the MPEG data transmission unit 3
It is stored in the buffer in 0a. When the preparation for data transmission is completed, the MPEG data transmission unit 30a activates the data ready signal DRN.

Subsequently, at time t3, when all of data ready signals DR1 to DRN are activated, data transmission timing control unit 28 simultaneously activates send enable signals SE1 to SEN. In response, the MPEG data transmitting units 30 and 30a shown in FIGS. 2 and 3 respectively direct the MPEG data decoding units 34 and 34a to
Transmission of the GOP1 trans-stream data TS1 and TSN corresponding to the first 15 frames of images is started.
Here, a GOP (Group Of Picture) refers to a screen group structure including at least one intra-frame coded screen.
GOPN indicates the N-th GOP (N is a natural number).

From time t4 to time t5, the decoded image signal for 15 frames corresponding to GOP1
The data is output from the G data decoding units 34 and 34a. GO
The time at which the transfer of P1 ends depends on the pattern of the image to be reproduced. In FIG. 4, the transfer completion time of GOP1 is different between the playback devices 10 # 1 and 10 # N. However, the decoding start time and the reproduction start time are set in consideration of the time required for the MPEG data decoding unit 34 to decode and the like, and these times are included as data in the data TS1 and TSN. Therefore, finally M
1 output from the PEG data decoding units 34 and 34a
Five frames are synchronized for each frame.

Subsequently, at time t5 to t6, GOP
15 frames corresponding to 2 are output from the MPEG data decoding units 34 and 34a.

The same processing is performed after time t6. That is, the data TS1, displayed as the output of the sending unit,
The transfer time of the TSN differs depending on the GOP number because the data amount is different, and the playback device 10 # 1 and the playback device 1
0 # N, but the MPEG data decoding unit 3
The 15 frames output from the 4, 34a are output in synchronization.

Next, control of a clock signal necessary for synchronizing frames will be described.

FIG. 5 shows the reproducing apparatus 10 # 1 and the reproducing apparatus 10
FIG. 11 is a diagram showing a state of a clock signal when data is reproduced independently of $ N.

Referring to FIG. 5, when the synchronous operation is not performed, DDCLK shown in FIGS. 2 and 3 is generated independently as DDCLK1 and DDCLKN, respectively. The phase is different from the decode reference clock DDCLKN (time t1). The data transfer clock DCLK1 and the data transfer clock DCLKN have different phases (time t2). Also, the MPEG data decoding unit 34,
The phase of the data decode reference clocks DDCLK1 and DDCLKN is adjusted in accordance with the time stamps of the data TS1 and TSN by the PLL circuit included in the data decode reference clock IDDCLK.
1, IDDCLKN is output. However, the data decode reference clock IDDCLK1 and the data decode reference clock IDDCLKN have different phases (time t3).

Therefore, the MPEG data decoding unit 3
4 and the video / audio signal OUTN output from the MPEG data decoding unit 34a,
Normally, frame synchronization is not achieved.

As described above, each reproducing apparatus can independently reproduce a digitally encoded video / audio signal recorded on a magneto-optical disk or the like. Required. That is, as shown in FIG. 1, one of the plurality of playback devices is a master playback device, the other playback device is a slave playback device, and a data transmission reference clock DSCLK and a data decode reference clock DDCLK are provided therebetween. When shared, synchronized playback becomes possible.

FIG. 6 is a waveform diagram showing the state of each clock signal when synchronous operation is performed in the digital video reproduction system shown in FIG.

Referring to FIGS. 2 and 6, reproducing apparatus 10 # 1
, The data transmission reference clock generator 26 generates the data transmission reference clock DSCLK, and
The G data sending unit 30 generates a data transfer clock DCLK1.

The data decode reference clock generator 32 generates a data decode reference clock DDCLK. The data TS1 transferred to the MPEG data decoding unit in synchronization with the data transfer clock DCLK1 includes a time stamp. Based on the time stamp, a data decoding reference clock DDC is generated by a PLL circuit included in the MPEG data decoding unit 34.
The phase of LK is corrected and adjusted data decode reference clock IDDCLK1 is generated, and decode processing is performed according to data decode reference clock IDDCLK1.

Referring to FIGS. 3 and 6, MPEG data transmitting section 30a generates data transfer clock DCLKN in accordance with data transmission reference clock DSCLK and send enable signal SEN. MPEG data transmission unit 30
Since a is supplied with the data transmission reference clock DSCLK common to the MPEG data transmission unit 30 shown in FIG. 2, the phase of the data transfer clock DCLKN can be aligned with the phase of the data transfer clock DCLK1 (see time t2). ).

The MPEG data decoder 34a is supplied with a data decode reference clock DDCLK common to the MPEG data decoder 34 in FIG. 2 (see time t1). For this reason, the PLL circuit included in the MPEG data decoding unit 34a sets the phase of the internally generated data decoding reference clock IDDCLKN to the data decoding reference clock IDDCLK generated by the MPEG data decoding unit 34 in the reproducing apparatus 10 # 1.
CLK1 can be aligned with the phase (see time t3).

That is, the data decode reference clock ID
A reference clock DSCLK resulting from the generation of DCLK1,
Since DDCLK is commonly used in the reproduction devices 10 # 1 and 10 # N, the data decode reference clock IDDCL is used.
The phase of KN is set to the data decode reference clock IDDCLK.
Can be equal to 1.

The MP stored in the storage unit 24a
The EG data is data to be reproduced in synchronization with the MPEG data stored in the storage unit 24 shown in FIG. In other words, even if the decoding start time differs for each image, the display start time is finally the same. If the phases of the data transfer clock DCLK1 and the data transfer clock DCLKN are the same, and if the phase of the data decode reference clock IDDCLK1 and the phase of the data decode reference clock IDDCLKN are the same, the outputs from the MPEG data decoders 34 and 34a are respectively provided. If the video and audio signals to be performed are initially frame-synchronized, frame synchronization will be achieved.

In principle, the video and audio output signals between the playback devices can be synchronized by aligning the phases of the clock signals. However, the GEN-Lock1 shown in FIG.
By providing 2, a fine adjustment of the synchronization is finally performed, so that a more accurate synchronized multi-channel video signal can be obtained, and the image can be switched smoothly.

As described above, if the reproduction of the video / audio signal is started in a synchronized state by first sharing a plurality of types of clock signals used in each reproducing apparatus, the synchronization is thereafter performed. Reproduction can be continued while maintaining the taken state. [Processing at Start of Reproduction] Next, a description will be given of starting reproduction of a video / audio signal in a state where all reproduction apparatuses are synchronized at the same time.

FIG. 7 is a flowchart showing a control flow of master reproducing apparatus 10 # 1.

Referring to FIG. 7, first, in step S1, an instruction is given to select a work to be reproduced from the works stored in storage unit 24 shown in FIG. And
The playback device 10 # 1 shown in FIG.
Depending on the OL, the playback device 10 # 2 to 10 # N of each slave
To tell the work to play.

Subsequently, data is read from the storage unit 24 shown in FIG. 2 and sent to the MPEG data transmission unit 30. Further, in step S4, the MPEG data transmission unit 30
It is determined whether or not one of a plurality of built-in data buffers has completed data storage and is ready for data transmission. If data accumulation has not been completed yet, that is, if the data is not “buffer full”, the process returns to step S3.

When the data is completely stored in the data buffer incorporated in the MPEG data transmission unit 30 and the data is ready for transfer, the process proceeds to step S5, where the MPEG data transmission unit 30 controls the data ready signal DR1 to control the data transmission timing. Output to the unit 28.

Subsequently, in step S6, the MPEG
When the data TS1 is transmitted from the data transmission unit 30 for the first time, the process proceeds to step S7.

In step S7, it is determined whether or not data ready signals DR1 to DRN have been input to data transmission timing control section 28 from all slave playback devices. If all the data ready signals have not been received yet, the process stays at step S7 and waits until all the data ready signals are prepared. After confirming that all the data ready signals DR1 to DRN have been activated, the data transmission timing control section 28 proceeds to step S8, where the data transmission timing control section 28 transmits the send enable signals SE1 to SEN to the master reproducing apparatus 10 #. 1 MPE
MPEG of the G data transmission unit 30 and the playback device of each slave
The data is output to the data transmission unit 30a. Then, the process proceeds to step S9.

In step S6, if the MPEG data is not transmitted from the MPEG data transmitting section 30 for the first time, the process proceeds directly to step S9 without performing steps S7 and S8.

In step S9, the data TS1 is transmitted from the MPEG data transmitting section 30. This data T
S1 is transferred in synchronization with the data transfer clock DCLK1, but these are clocks having a common phase generated based on the data transmission reference clock DSCLK in each slave device. In step S10, the received data TS1 and the data decode reference clock DD
CLK included in the MPEG decoding unit 34 in accordance with
The time of the system is adjusted by the LL circuit. Then, based on the adjusted clock, the MPEG data decoding unit 34 decodes the MPEG data. The MPEG data decoding unit 34 has a built-in buffer, and the decoding process is performed in parallel with other processes such as a data transfer process. When the process in step S9 ends, the process proceeds to step S11. Step S11
If all the data of the work to be reproduced have not been transmitted, the process returns to step S3. On the other hand, when the transmission of all the data of the specified work is completed, the reproduction processing ends.

FIG. 8 is a flowchart showing the processing of the slave playback device. Referring to FIGS. 3 and 8, in step S21, main controller 22a detects whether or not an instruction to start reproduction or the like has been given from the master reproduction device. If the instruction has been received, the process proceeds to step S22, and the storage unit 24
The data is read from a and transferred to the MPEG data transmission unit.

Subsequently, in step S23, the MPEG
It is determined whether data has been accumulated in the data transfer buffer built in the data transmission unit 30a. If data accumulation has not been completed, the process returns to step S22. On the other hand, if the data storage is completed, step S2
Proceed to 4.

In step S24, the MPEG data transmitting section 30a activates the data ready signal DRN.

The data TSN is transmitted from the MPEG data transmitting section 30a to the MPEG data decoding section 34a.
Is output for the first time, it waits for the input of the send enable signal SEN from the master reproducing apparatus 10 # 1. If the send enable signal SEN has been received from the master reproducing device 10 # 1, the process proceeds to step S27.

On the other hand, in step S25, the MPEG
If the transmission of the data TSN from the data transmission unit 30a is not the first time, the process directly proceeds to the step S27 without performing the step S26.

In step S27, the transmission of the data TSN is started from the MPEG data transmitting section 30a. This data TSN is transmitted in synchronization with the data transfer clock DCLKN, but as described above, the data transfer clock DCLKN
CLKN is a clock having the same phase as the data transfer clock DCLK1 used in the master reproducing apparatus.

Then, in step S28, the received data TSN and the data decode reference clock DDCLK cause the MPEG data decoding unit 34a to generate
The system time is adjusted by the LL circuit, and
The MPEG data decoding unit 34a performs data decoding.

Subsequently, in step S29, it is determined whether or not all the pieces of work data have been transmitted. If all the pieces of data have not been transmitted yet, the flow returns to step S22. On the other hand, when the transmission of all the data is completed, the reproduction of the work ends.

As described above, by synchronizing the clocks and simultaneously starting to output the data TS1 and TSN, a plurality of video reproducing apparatuses using digitally encoded data such as MPEG are synchronously operated. It is possible to realize a digital video reproduction system that can reproduce a two-dimensional image (plane image) by itself and a synchronous reproduction of a three-dimensional image (stereo image) or a multi-channel image by a plurality of units. it can. [Pause processing] In addition, there is a problem in that the reproduction position is resumed after the pause or the reproduction position is moved by jumping in synchronization with a plurality of units. By creating and recording the basic index data and the common index data of the work data with the system described above, it is possible to cope with the problem.

The MPEG data includes an I picture, a P picture and a B picture. Among these, a picture that can be decoded alone is an I picture.

In particular, in MPEG data having a GOP structure, the GOP includes one or more I pictures. For example, if an I picture is arranged at the head of a GOP and a data structure is used in which 15 frames constitute one GOP, the I picture is surely inserted at one place in about 0.5 seconds.
In this way, by using the I picture at the head of the GOP, special reproduction such as jumping and fast-forwarding can be easily performed.

Assuming that the GOP numbers from the beginning of the TS file are 1 to M, the reproduction time of the work at this time is about 0.5 (second) × M. In each reproducing apparatus, the basic unit of data transfer is the unit of the first I picture of the GOP in the case of GOP or fast-forward reproduction.

The basic index data is a table showing the correspondence between the relative numbers of the I-pictures and the recording positions in the TS file.

FIG. 9 is a diagram showing the structure of the basic index data of the master reproducing apparatus. FIG. 10 is a diagram showing the structure of the basic index data of the slave playback device.

Referring to FIG. 9 and FIG. 10, when considering a synchronous operation by a plurality of units, basically the MPEG data of any reproduction system has M GOPs. This is because works that are played back synchronously are works of the same length and start and end at the same time.

On the other hand, the position of the head data of the GOP in the TS data, that is, the time Pmx and Psnx (x is an integer from 1 to M) transmitted from the MPEG data transmitting unit 30 do not always match. Further, the data amount Xmx and Xsnx (x is an integer from 1 to M) up to the next picture do not always match. Therefore, when the reproduction of the images is simultaneously started in the master and slave reproduction devices and then the reproduction is attempted to be temporarily stopped, the frame displayed at the time of the pause may be different.

That is, the master reproducing apparatus instructs the slave reproducing apparatus to stop data transmission from the MPEG data transmitting section, and the M of the master reproducing system itself.
Even if the data transmission from the PEG data transmission unit is stopped, there is a possibility that the frame displayed when the data is temporarily stopped is different.

This is because, since MPEG data is stored in the data buffer of the MPEG data decoding unit, when all the information is decoded, the frame displayed for each playback device may be different. .

When such a situation arises, it is inconvenient for the synchronous operation system. Therefore, common index data is newly provided, and the master reproduction system refers to the common index data and the master reproduction system individually instructs the slave reproduction system. Is instructed to stop the data transfer of the MPEG data transmitting section, and the screen of the same frame number is displayed when the reproduction of all the reproduction systems is stopped.

The common index data is created as follows. First, the relative playback times are equal, and
Pick up a frame that is an I picture.
Then, data TS1 to TSN including the corresponding picture
Of packets arrives at the decoder based on the earliest arrival time. The other of the data TS1 to TSN is
For example, time information such as the number of clocks delayed from the reference data may be calculated and recorded in association with each other, or may be managed by a GOP number as described later.

Regarding the holding of the index data, each system may have N sets of common index data, and the common index data is held only by the master system, and is controlled by the slave via the LAN or the like each time. You may. When only the master system has the common index data, each slave may only have the index information of the data to be reproduced by itself.

FIG. 11 is a diagram showing the structure of common index data provided for synchronous operation.

FIG. 12 is a diagram showing the flow of data during reproduction for explanation of common index data.

Referring to FIG. 11, GO of the master reproducing apparatus
The largest GOP number in the slave playback device at the same time is recorded in association with the P number. That is, the GOP numbers “1”, “2”,
The maximum GOP numbers in the slave playback device corresponding to "3" are "1", "2", and "2", respectively.

Then, the GOP number “2” of the master reproducing device
The largest GOP number among the slave playback devices at the same time corresponding to “00” is “202”.
The situation shown at time t12 corresponds to this case.

15 to be reproduced at times t11 to t13
During output of the decoded signal for the frame, at time t12
, The master playback device receives a pause instruction. When the master playback device receives the stop instruction, the number of the GOP sending data to the decoding unit is “200”.
It is. At this time, data corresponding to the GOP number “202” is being sent to the decoding unit in the slave playback device.

When the master playback device refers to the common index data, the slave playback device has GOP number “20”.
It can be seen that the data corresponding to 2 "is being transmitted to the decoding unit.
TS1 to the decoding unit until the data of the second GOP
And instructs all of the other slave reproducing apparatuses to transmit TS2 to TSN to the decoding unit up to the data of the 202nd GOP and to stop. By doing so, all playback devices are GOP
The operation stops when the image of the frame corresponding to “202” is reproduced.

That is, at the time of suspension and resumption,
The master playback device knows which GOP data is being sent to the decoder when the master playback device is paused.
On the basis of the common index data, it is checked which GOP data the other slave device is currently sending to the decoder.

At this time, based on the system that is transmitting the GOP data with the highest number, the master reproduction apparatus stops the slave reproduction so that all the reproduction apparatuses stop transferring the GOP data corresponding to this number. An instruction is issued by issuing a control signal to the device. In consideration of the delay of the instruction, the number of the GOP to be transferred may be increased by 1 or a little.

When the reproduction is resumed, the G
The OP is transmitted again from the MPEG data transmission unit, or transmission is started from the GOP next to the GOP whose transfer has been completed. At this time, the same processing as in the flowcharts shown in FIGS. 7 and 8 is performed.

As described above, by preparing and holding the index data in advance, it is possible to synchronize the frames in a plurality of playback devices without any problem even during a pause.

The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0100]

As described above, according to the present invention,
A plurality of video reproducing apparatuses using compressed digitally encoded data such as MPEG can be operated synchronously, and a single unit can reproduce a two-dimensional image, and a plurality of units can reproduce a three-dimensional or multi-channel image. A digital video playback system capable of performing the above can be realized.

Furthermore, synchronous operation can be performed without any problem even during pause or resumption of reproduction.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a digital video playback system 1 of the present invention.

FIG. 2 is a block diagram showing a configuration of a reproducing apparatus 10 # 1 shown in FIG.

FIG. 3 is a block diagram showing a configuration of a reproducing apparatus 10 # N shown in FIG.

FIG. 4 is a diagram showing a data flow when a master playback device 10 # 1 and a slave playback device 10 # N operate in synchronization and data is played back in the playback device.

FIG. 5 is a diagram showing a state of a clock signal when the reproducing apparatus 10 # 1 and the reproducing apparatus 10 # N reproduce data independently.

FIG. 6 is a diagram illustrating states of respective clock signals when synchronous operation is performed in the digital video reproduction system illustrated in FIG. 1;

FIG. 7 is a flowchart showing a control flow of the master playback device 10 # 1.

FIG. 8 is a flowchart showing processing of the slave playback device.

FIG. 9 is a diagram showing the structure of basic index data of a master playback device.

FIG. 10 is a diagram showing the structure of basic index data of a slave playback device.

FIG. 11 is a diagram showing a structure of common index data provided for synchronous operation.

FIG. 12 is a diagram illustrating a flow of data during reproduction for explanation of common index data.

[Explanation of symbols]

1 Digital video playback system, 10 # 1-10 # N
Reproduction device, 12 GEN-Lock unit, 22, 22a
Main control unit, 24, 24a storage unit, 26 data transmission reference clock generation unit, 28 data transmission timing control unit, 30, 30a data transmission unit, 32 data decode reference clock generation unit, 34, 34a data decoding unit, AVOUT1 Output signal, BTS1, BT
SN data, CONTROL control signal, DCLK
1, DCLKN data transfer clock, DDCLK1,
DDCLKN Data decode reference clock, DR1
DRN data ready signal, DSCLK data transmission reference clock, Hsync horizontal synchronization signal, IDDCLK
1, IDDCLKN Data decode reference clock, I
DX1, IDXN index data, OUT1 to O
UTN video / audio signal, SE1-SEN send enable signal, TS1-TSN data, Vsync vertical synchronization signal.

Continued on the front page F-term (reference) 5C053 FA23 GB10 GB11 GB37 JA27 JA28 5C061 AA29 AB21 5D066 BA03 BA07 SA07 SC03 SE01 SF10

Claims (6)

[Claims] 1. A digitally encoded video / audio signal is
A digital video playback system that plays back in synchronization with channels or more, comprising: a first playback unit that plays back a first video and audio signal, wherein the first playback unit corresponds to the first video and audio signal First storage means for holding digitally encoded first data to be received, and after temporarily receiving and storing the first data from the first storage means, sends out the first data together with a first transfer clock. First data transmission means; first reference clock generation means for generating a data transmission reference clock serving as a reference of the first transfer clock; and first data and first data from the first data transmission means. First decoding means for receiving and decoding the transfer clock, and second reference clock generating means for generating a decode reference clock serving as a reference for decoding by the first decoding means. And further comprising a second playback device that plays back a second video / audio signal, wherein the second playback device converts digitally encoded second data corresponding to the second video / audio signal. A second storage unit for holding, and a second storage unit for receiving the second data from the second storage unit and temporarily storing the second data, and then synchronizing with the first transfer clock according to the data transmission reference clock. A second data transmitting means for generating a transfer clock of the second data and transmitting the second transfer clock together with the second data; and transmitting the second data and the second transfer clock from the second data transmitting means. Receiving the second data in accordance with the transfer clock and the decode reference clock. 2. The first reproducing apparatus, wherein the first and second data transmitting means are respectively the first and second data transmitting means.
And timing control means for controlling a timing of transmitting the second data, wherein the timing control means includes means for transmitting the first and second data when the synchronous reproduction of the first and second video / audio signals is started. 2. The digital device according to claim 1, further comprising, after waiting until both are ready to send, instructs the first and second data sending means to simultaneously output the first and second data, respectively. Video playback system. 3. The digital video reproduction system according to claim 1, further comprising: a synchronization coupling unit that adjusts a timing so that the outputs of the first and second decoding units match a phase according to an external synchronization signal. 4. The first data includes a plurality of first data corresponding to a plurality of screens on which intra-screen compression is performed.
Screen data, and a plurality of second screen data respectively corresponding to a plurality of screens to be subjected to predictive encoding using the plurality of first screen data, wherein the second data is in a screen A plurality of third screen data respectively corresponding to a plurality of screens to be compressed; and a plurality of fourth screen data respectively corresponding to a plurality of screens to be subjected to predictive encoding using the plurality of third screen data. Wherein the first storage means reproduces the first screen data corresponding to the time at which the first screen data is transmitted from the first data transmission means and the first screen data. 3 holds index data indicating the correspondence between the screen data and the time sent from the second data sending means, and the first reproducing means reads the index data when a pause instruction is received. See above 2. The digital video reproduction system according to claim 1, further comprising control means for instructing the first and second data transmission units to stop data transmission. 5. The third index data to be sent from the second data sending means when the first screen is sent from the first data sending means.
5. A correspondence relationship between the first screen and the first screen is shown.
A digital video playback system according to claim 1. 6. The digital encoding method is MPEG.
The digital video playback system according to claim 4, wherein the first and third screen data are I-picture data.