JP3593773B2 - Reproduction device and signal processing method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reproducing apparatus and a signal processing method, and more particularly to a reproducing apparatus and a signal processing method for reproducing a digital data stream recorded on a recording medium and transmitting the digital data stream to another device via a digital interface. .
[0002]
[Prior art]
In recent years, in the United States and European countries, MPEG (Moving Picture)
A system that encodes a video signal and an audio signal by applying a high-efficiency encoding technique such as Image Coding Experts Group), transmits the encoded signal via a communication satellite or the like, and demodulates the signal on a receiving side is becoming popular. is there.
[0003]
In these systems, a dedicated receiving / demodulating device is required on the receiving side. In this receiver / demodulator, a portion for selecting a transport stream of a desired channel from a transport stream in which data of a plurality of channels is multiplexed, and video data and audio of a desired program from the transport stream of a desired channel. It has a part for separating data and a part for decoding the separated video data and audio data.
[0004]
Further, in this system, the multiplexed transport stream is received by the receiving / demodulating device so that the transport stream of the desired channel can be received and the video data and audio data of the desired program can be separated. PSI (Program Specific Information: Program Specification Information), EPG (Electric Program Guide: Electronic Program Guide), or SI (Service Information: Service Information) is added to it.
[0005]
[Problems to be solved by the invention]
Video tape recorders (hereinafter referred to as DVCRs) that encode and record / reproduce video and audio signals have been proposed. It has been considered that the above-mentioned digital broadcast video data and audio data are recorded / reproduced without decoding on such a DVCR (Yukio Kubota, “Digital Video Reader”, pp. 140-152, (Ohm Co., Ltd., August 25, 1995).
[0006]
The present invention reproduces a digital data stream recorded on a recording medium and transmits the digital data stream to another device via a digital interface, as in the case where a DVTR continuously reproduces a plurality of digital broadcast programs as described above. A reproducing device and a signal processing device for quickly decoding video data and audio data on the other device side even when the program is changed or discontinuous, and for preventing the decoded output from being interrupted. The purpose is to provide a method.
[0007]
[Means for Solving the Problems]
In order to solve the above problem, a playback device according to the present invention is a playback device capable of playing back a digital data stream recorded on a recording medium and transmitting the stream to another device via a digital interface. Detecting means for detecting a transition from the reproduction stop state to the reproduction start state, and generating means for generating discontinuity information in response to detection of the transition to the reproduction start state, wherein the reproduced digital data The stream and the generated discontinuous information are transmitted to the other device via the digital interface.
[0008]
Also, the signal processing method according to the present invention is a signal processing method in which a digital data stream recorded on a recording medium is reproduced and transmitted to another device via a digital interface. Detecting the transition to the reproduction start state, generating discontinuous information in response to the detection of the transition to the reproduction start state, and transmitting the reproduced digital data stream and the generated discontinuous information to the digital interface. Characterized in that the data is transmitted to the other device via a.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a digital signal processing device to which the present invention is applied. This digital signal processing device is called an IRD (Integrated Receiver Decoder).
[0011]
The digital signal processing apparatus receives an RF signal sent from a down converter (not shown) and selects a transport stream of a desired channel from a front end 1 and a transport stream selected by the front end 1 from the transport stream. A demultiplexer 2 for separating MPEG video data, MPEG audio data, and additional information of a desired program from each other and a buffer memory 3 for temporarily storing data input / output through the demultiplexer 2 are provided.
[0012]
The digital signal processing apparatus includes an MPEG video decoder 4 for decoding video data separated by the demultiplexer 2, an MPEG audio decoder 5 for decoding audio data separated by the demultiplexer 2, and an MPEG video decoder 4. An NTSC encoder 6 for converting the decoded video signal into an NTSC video signal, a D / A converter 7 for converting the output of the NTSC encoder 6 into an analog signal, and a D / A converter 8 for converting the output of the MPEG audio decoder 5 into an analog signal. And The MPEG video decoder 4 is provided with a buffer memory 4a for temporarily storing video data, and the MPEG audio decoder 5 is provided with a buffer memory 5a for temporarily storing audio data.
[0013]
Further, this digital signal processing device includes a microcomputer (hereinafter, referred to as a microcomputer) 9 for controlling the operation of the entire device, a front panel 10, and MPEG video data and MPEG audio data separated by the demultiplexer 2 and external information. And a digital interface 11 for transmitting MPEG video data, MPEG audio data, and additional information received from outside to the demultiplexer 2.
[0014]
The front end 1 includes a tuner, a QPSK demodulator, and an error correction circuit. The front end 1 converts a multiplexed transport stream of a plurality of channels into a transport stream of a desired channel specified by the user on the front panel 10. Select and perform QPSK demodulation, and further detect and correct errors.
[0015]
FIG. 2 shows an example of a transport stream for one channel. As shown in this figure, a plurality of programs (here, program numbers 1 to 3 are multiplexed) are multiplexed in a transport stream of one channel. Here, the program is a virtual broadcasting channel, which is, for example, a broadcasting service of the NHK satellite No. 1 and the NHK satellite No. 2 in the current broadcasting in Japan.
[0016]
The data of each program is packetized with a predetermined length (188 bytes), and has a header at the beginning. The header is provided with a PID (Packet Identification) for identifying data.
[0017]
The transport stream of the desired channel selected by the front end 1 is temporarily written to the buffer memory 3 through the demultiplexer 2. Then, the MPEG video data and the MPEG audio data of the desired program are read and separated therefrom, and the video data is sent to the MPEG video decoder 4 and the audio data is sent to the MPEG audio decoder 5. In FIG. 2, video data and audio data of the program 2 are separated.
[0018]
At the time of this separation, the PID (packet ID) assigned to the packet is viewed. If it is a PID for identifying video data and audio data of a desired program, the PID is sent to the MPEG video decoder 4 and the MPEG audio decoder 5, respectively. In FIG. 2, the PID assigned to the video data of the program 2 is “xx”, and the PID assigned to the audio data is “yy”. A method of knowing the correspondence between the program number and the PID in the digital signal processing device will be described later.
[0019]
The video data sent to the MPEG video decoder 4 is stored in the buffer memory 4a, and is read and decoded as appropriate. The decoded video data is converted into an NTSC video signal by an NTSC encoder 6, converted to an analog video signal by a D / A converter 7, and supplied to an external monitor device (not shown). The audio data sent to the MPEG audio decoder 5 is stored in the buffer memory 5a, and is read and decoded as appropriate. The decoded audio data is converted into an analog audio signal by the D / A converter 8, and then supplied to a speaker (not shown) such as a monitor device.
[0020]
As described above, the digital broadcast video signal and audio signal can be received, decoded, and displayed on the monitor device.
[0021]
Next, the additional information will be described. As described above, PSI (program use information), EPG (electronic program guide) or SI (service information) is added to the multiplexed bit stream. Here, a description will be given of PSI specified by MPEG and SI specified by DVB (Digital Video Broadcasting) system, which is digital broadcasting in Europe.
[0022]
{Circle around (1)}: PAT (Programme Association Table)
This table is defined by MPEG, and the PID (packet ID) is 0. The main contents are the description of the PID of the NIT and the PID of the PMT described later.
[0023]
{Circle around (2)}: PMT (Programmable Map Table)
This table is also defined by MPEG, and the PID is determined by the above-described PAT. The main contents are a description of a correspondence between a program number and a PID and a description of a PID of an ECM (scramble data accompanying a program).
[0024]
{Circle around (3)}: CAT (Conditional Access Table)
This table is also defined by MPEG, and the PID is 1. The main content is a description of EMM (scramble information for customers).
[0025]
{Circle over (4)}: NIT (Network Information Table)
The PID is 0010. The main contents are a description of a network name (satellite name, terrestrial transmission station, etc.) and a description of a modulation method and a frequency for each transport stream (physical channel).
[0026]
The following table is specified in DVB.
{Circle around (5)}: BAT (Bouquet Association Table)
The PID is 0011. The main contents are the name of a bouquet (program provider) and a description of a destination country, the contents of a service related to a transport stream (physical channel), and a description of a CAS (Conditional Access Service System) system.
[0027]
{Circle around (6)}: SDT (Service Description Table)
The PID is 0011. The main content is a description of a transport stream (physical channel) such as a service ID included therein and a name of a bouquet thereof. Here, the service ID is a broadcast channel such as NHK Satellite 1 and NHK Satellite 2. That is, it is the same as the program number defined in MPEG.
[0028]
{Circle around (7)}: EIT (Event Information Table)
The PID is 0012. The main contents are the description of the event ID and its start time, broadcast time, program contents, and the like. Then, a transport stream ID and a service ID are described for each event ID. Here, the event is, for example, a program such as "7:00 News (broadcast on December 1)".
[0029]
(8): TDT (Time and Data Table)
The PID is 0010. The main content is the description of information in Coordinated Universal Time. Using the TDT, the time of a clock (not shown) in the apparatus can be adjusted.
[0030]
(9): RST (Running Status Table)
The PID is 0013. The main content is a description of the event execution status. That is, a description such as before the start, execution, and end of a certain event is made.
[0031]
Next, how the microcomputer 9 in the digital signal processing device processes the above-described PSI and SI will be described.
[0032]
First, in the digital signal processing device, constants and the like are set in accordance with the system of each network. Since this information is described in the NIT, a modulation method, a frequency, a bit rate, an error correction method, and the like can be obtained for each transport stream. After the setting, these pieces of information are stored in an EEPROM (not shown) of the microcomputer 9.
[0033]
Next, an event search is performed using the EIT. Each broadcast event is given a unique event ID, the name and contents of the broadcast program are described in the EIT together with the start time, and the transport stream ID and service ID are described for each event. Therefore, the transport stream ID is determined from the EIT, the digital signal processing device is set using the transport stream constant obtained in the NIT, and the transport stream of the desired channel is selected.
[0034]
The processing for selecting the transport stream of the desired channel in the front end 1 has been described above. Next, the processing of the microcomputer 9 when sending the output of the demultiplexer 2 to the MPEG video decoder 4 and the MPEG audio decoder 5 will be described.
[0035]
FIG. 3 shows an example of the transport stream input to the demultiplexer 2 and the contents of the PAT and PMT therein. FIG. 4 shows an example of the internal configuration of the buffer memory 3. FIG. 5 is a diagram showing the flow of this processing. Here, description will be made assuming that the broadcast of program number 1 is selected.
[0036]
First, as shown in step S1 of FIG. 5, the output of the front end 1 is written into the buffer memory 3 through the demultiplexer 2. In the buffer memory 3, as shown in FIG. 4, storage areas 3A to 3C are defined for each data, so that data is written in each area.
[0037]
Next, as shown in step S2, a PAT is searched for from the additional information written in the additional information area 3C of the buffer memory 3. In this process, a packet having a PID of 0 may be searched for. As shown in FIG. 3 (2), the PAT describes the PID of the PMT for each program (here, the PID of the PMT1 is “cc” and the PID of the PMT2 is “dd”).
[0038]
Therefore, next, a packet whose PID is “cc” is searched. Thereby, PMT1 corresponding to program number 1 can be detected. As shown in FIG. 3 (3), PMT1 describes MPEG video data of program number 1, MPEG audio data, and PID of ECM.
[0039]
Therefore, when watching the broadcast of program number 1, the packet whose PID is "aa" is read from the MPEG video data area 3A of the buffer memory 3, sent to the MPEG video decoder 4 through the demultiplexer 2, and read from the MPEG audio data area 3B. The packet whose PID is “ab” is read and sent to the MPEG audio decoder 5 through the demultiplexer 2. As shown in FIG. 2, at this time, only data excluding the header is sent. Also, the scramble is decoded using the ECM information described in the packet whose PID is “xx”.
[0040]
If a broadcast of program number 2 is to be watched, a packet having a PID of “dd” is similarly searched for. As shown in FIG. 3 (4), the PID of the video data, the audio data, and the ECM of the program number 2 are described in this packet. Therefore, a packet whose PID is "ba" is read from the MPEG video data area 3A and sent to the MPEG video decoder 4, and a packet whose PID is "bb" is read from the MPEG audio data area 3B and sent to the MPEG audio decoder 5. Also, the scramble is decoded using the ECM information described in the packet with the PID “zz”.
[0041]
The normal processing for decoding the transport stream input from the front end 1 has been described above. The digital signal processing device in FIG. 1 can further output the MPEG video data, MPEG audio data, and additional information separated by the demultiplexer 2 to an external recording / reproducing device, for example, a DVCR via the digital interface 11. In addition, MPEG video data, MPEG audio data, and additional information output from an external recording / reproducing device can be received via the digital interface 11 and sent to the demultiplexer 2. Next, these processes will be described.
[0042]
First, the processing of the microcomputer 9 when transmitting the output of the demultiplexer 2 from the digital interface 11 to the outside will be described. Since most of this processing is the same as the above-described normal processing, only different points will be described.
[0043]
The MPEG video data and the MPEG audio data are sent to the digital interface 11 with the packet header attached. That is, when the microcomputer 9 reads out the data from the buffer memory 3, it reads out the entire header and sends it to the digital interface 11 through the demultiplexer 2.
[0044]
The PSI and SI are also sent to the digital interface 11 with the header attached. However, the PAT leaves only the PID designating the PMT of the selected program number, and removes the others. For example, when program number 1 is selected, only the PID of PMT1 (“cc” in the case of FIG. 3) is left, and the others are removed.
[0045]
The data sent to the digital interface 11 in this manner is sent out from here. The digital interface 11 is based on, for example, IEEE-1394. In this case, the data is output in an IEEE-1394 isochronous packet. The isochronous packet output from the digital interface 11 is sent to an external DVCR. Then, data is taken out from the isochronous packet, an error correction code in a recording system is added thereto, and after being subjected to a channel coding process, it is recorded.
[0046]
Next, a case where data recorded on the DVCR as described above is reproduced and input to the digital signal processing device will be described. The external DVCR puts the reproduced data in an isochronous packet and outputs it. The isochronous packet is input to the digital interface 11, where the original MPEG video data, MPEG video data, and additional information are extracted and written into the buffer memory 3 through the demultiplexer 2.
[0047]
The processing of the MPEG video data and the MPEG audio data written in the buffer memory 3 is the same as the processing of these data in the transport stream input from the front end 1 described above. On the other hand, the microcomputer 9 processes the PSI and SI written in the buffer memory 3 as follows.
[0048]
PAT and PMT are used as they are. As described above, when data is output from the digital signal processing device to an external DVCR, only the PID designating the PMT of the program number selected from the PAT is left, and the others are removed. Only the PID designating the PMT of the program number being input is described in the PAT in the data input from. Therefore, the PMT is searched by looking at the PAT, and the MPEG video data and the MPEG audio data of the program being input can be read by looking at the PMT. The read MPEG video data and MPEG audio data are sent to the MPEG video decoder 4 and the MPEG audio decoder 5 through the demultiplexer 2, and thereafter processed in the same manner as these data from the front end 1.
[0049]
As for the EIT, only the actual and present information of the program described in the PAT is decoded, and the other information is ignored. Here, “actual” means a transport stream of the selected channel, and “present” means that the selected program is currently being broadcast.
[0050]
As for the RST, only those relating to the program described in the PAT are decoded, and the others are ignored. As for the SDT, only the actual one of the program described in the PAT is decoded, and the others are ignored.
[0051]
The NIT is necessary for setting in the front end 1 but is not required in the demultiplexer 2 and is ignored. BAT is similarly ignored.
[0052]
Regarding the TDT, when a reproduction signal of an external DVCR is input, the TDT in the reproduction signal indicates the time at the time of recording and does not indicate the current time, and thus the TDT is ignored. As a result, it is possible to avoid a situation where the internal clock is set to an incorrect time when setting the time.
[0053]
Further, a case where a plurality of programs are continuously input from an external DVCR will be described. As described above, the microcomputer 9 searches the PAT for the PMT, and reads the MPEG video data and the MPEG audio data of the program being input from the external DVCR by looking at the PMT. However, when the external DVCR is continuously outputting a plurality of programs and the program is switched, the microcomputer 9 newly searches the PAT for the PMT, searches for the PMT, and stores the MPEG video data and the MPEG video data of the switched program. MPEG audio data cannot be read. Further, in the MPEG video decoder 4 and the MPEG audio decoder 5, since the past data is used for the decoding process, when the program is switched, the data of the program before switching remaining in the buffer memories 4a and 5a is replaced. If it is not cleared, correct decoding cannot be performed.
[0054]
Similarly, if the SI is switched to a program with a different transport stream, it is necessary to rewrite the SI in the buffer memory 3.
[0055]
Thus, in the present embodiment, when the program being reproduced by the DVCR changes, a flag is provided in the header of the isochronous packet to identify the change. FIG. 6 is a diagram showing the format of an isochronous packet. Two bits of the tag (tag) field are 01 ₂ At this time, a 2-quadlet common isochronous packet header (hereinafter referred to as a CIP header) is inserted at the head of the data field. For the purpose of handling real-time data of digital audio / video signals such as digital video equipment and digital audio equipment, the value of tag is set to 01. ₂ And
[0056]
FIG. 7 shows the tag = 01. ₂ 4 shows a CIP header in the case of taking the value of. FIG. 8 shows an example of allocation of FMT (format type) in the CIP header. As shown in FIG. 6, FMT = 000000 ₂ DVCR at 100001 ₂ Specifies the format of the MPEG signal transmission. In the present embodiment, a discontinuity flag is provided for bit b0 of the FDF (format dependent field).
[0057]
The discontinuity flag is set to the “H (high)” level for a predetermined time (for example, one second) when the transport stream becomes discontinuous in the DVCR playback signal. Specifically, the DVCR records video auxiliary data (VAUX data) indicating a recording start position (REC START) and an end position (REC END) together with the video data when recording the video data. When the auxiliary data is detected, the discontinuity flag is set to “H (high)” level.
[0058]
Also, in the present embodiment, the discontinuity flag is set to the “H (high)” level even when the mode of the DVCR changes from stop (STOP) to reproduction (PB). Thus, even when the program is reproduced from the middle of the program, the data in the buffer memories 4a and 5a can be cleared and the SI in the buffer memory 3 can be rewritten.
[0059]
Further, in the present embodiment, a variable speed reproduction flag is provided in the bit b1 of the FDF. This is a flag that is set to “H (high)” level when the operation mode of the DVCR is slow and cue / review. At the time of such variable speed reproduction, only the MPEG I picture becomes valid data, so that the buffer memory 4a underflows, and as a result, the output of the MPEG video decoder 4 is interrupted until the next I picture is decoded. Would. Therefore, the digital signal processing device is configured such that, when this flag is detected, the last decoded I picture is output from the MPEG video decoder 4 until the next I picture is input.
[0060]
FIG. 9 is a flowchart showing processing of the microcomputer 9 at the time of external input.
First, the microcomputer 9 determines whether the input is an external input (step S11). Whether the input is an external input is determined based on the output of the front panel 10.
[0061]
Next, it is determined whether a discontinuity flag has been detected (step S12). This determination is made based on whether the digital interface 11 has detected the discontinuity flag shown in FIG. If the discontinuity flag is detected, a command to rewrite the PAT, PMT, and SI in the buffer memory 3 and clear the data in the buffer memories 4a and 5a are sent to the MPEG video decoder 4 and the MPEG audio decoder 5. (Step S13).
[0062]
Next, it is determined whether or not the variable speed reproduction flag has been detected (step S14). This determination is made based on whether or not the digital interface 11 has detected the variable speed reproduction flag shown in FIG. 7, as in step S12. If the variable speed reproduction flag has been detected, the MPEG video decoder 4 is instructed to keep outputting the last decoded I picture.
[0063]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to quickly decode video data and audio data when a program input from the outside changes.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a digital signal processing device to which the present invention has been applied.
FIG. 2 is a diagram illustrating an example of a transport stream for one channel.
FIG. 3 is a diagram showing an example of a transport stream input to a demultiplexer and the contents of PAT and PMT therein.
FIG. 4 is a diagram showing an example of an internal configuration of a buffer memory 3 in FIG. 1;
FIG. 5 is a diagram showing a processing flow of a microcomputer when sending an output of a demultiplexer to an MPEG video decoder and an MPEG audio decoder.
FIG. 6 is a diagram showing a format of an isochronous packet.
FIG. 7: tag = 01 ₂ FIG. 4 is a diagram illustrating a CIP header when the value of the CIP is taken.
FIG. 8 is a diagram illustrating an example of assignment of FMT (format type) in a CIP header.
FIG. 9 is a flowchart showing processing of the microcomputer at the time of external input.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Front end, 2 ... Demultiplexer, 4 ... MPEG video decoder, 5 ... MPEG audio decoder, 9 ... Microcomputer, 11 ... Digital interface

Claims (2)

In a reproducing apparatus capable of reproducing a digital data stream recorded on a recording medium and transmitting the digital data stream to another device via a digital interface,
Detecting means for detecting that the recording medium has transitioned from the reproduction stop state to the reproduction start state,
Generating means for generating discontinuous information in response to detection of the transition to the reproduction start state,
A reproducing apparatus, wherein the reproduced digital data stream and the generated discontinuous information are transmitted to the other device via the digital interface . A signal processing method for reproducing a digital data stream recorded on a recording medium and transmitting the digital data stream to another device via a digital interface,
Detecting that the recording medium has transitioned from the reproduction stop state to the reproduction start state,
In response to the detection of the transition to the playback start state, discontinuous information is generated,
A signal processing method, wherein the reproduced digital data stream and the generated discontinuous information are transmitted to the other device via the digital interface .

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