JP2001136138A - Digital video image/digital audio transmission method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize digital transmission between a DVD video player and a digital TV while simultaneously satisfying high quality and a low cost, which are reciprocal conditions to each other. SOLUTION: Digital video data and digital audio data are multiplexed as an MPEG transport stream, which is transmitted via an IEEE 1394. In this case, the multiplexed (ST106) MEPG transport stream is transmitted (ST108) according to any of a plurality of transmission levels (LD-1, LD-2, SD-1, SD-2, HD-1) separately stipulated in cross-reference with a 1st parameter restriction with respect to a parameter (coding pixel size and coding rate or the like) of the digital video image data, a 2nd parameter restriction with respect to a parameter (sampling frequency and quantized bit number or the like) of the digital audio data and a 3rd parameter restriction with respect to a multiplex parameter (multiplex rate such as 26 Mbps) (ST 104 in Figure 3).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a digital image,
The present invention relates to an improvement in a method for serially transmitting digital audio and the like via, for example, an IEEE1394 interface.

[0002] In particular, digital video and digital audio of a DVD video reproduced by a DVD video player or the like are multiplexed into an MPEG transport stream (MPEG-TS) under various parameter restrictions, and a receiving side device performs the multiplexing. The present invention relates to a digital video / digital audio transmission method devised so that MPEG-TS can be decoded without failure.

[0003]

2. Description of the Related Art As a digital interface for constructing a home multimedia network, IEEE is used.
E1394 is drawing attention. IEEE 1394,
It is a high-speed serial bus interface and has modes called an asynchronous (asynchronous) transfer mode and an isochronous transfer mode.

In the isochronous transfer mode, data is transmitted and received at regular intervals (125 μs), and a constant transfer rate is guaranteed. Therefore, the isochronous transfer mode is suitable for multimedia data transfer requiring real-time performance. In addition, any MPEG-TS (transport stream) can be transferred to IEEE
The rules for packetizing and transmitting on E1394 are I
EC61883-4.

[0005] DVD (Digital Versatile Disc) players / DVD video players have become widespread as typical digital video media in the home. Also,
A writable (recordable / readable) DVD recorder is about to appear. Further, devices such as a digital TV (DTV) for receiving a digital broadcast and a digital audio amplifier for decoding and reproducing compressed digital audio are expected to be more and more popular in the future.

There is naturally a demand for digital connection between digital media devices such as a DVD video player (recorder), a DTV, and a digital audio amplifier, and the IEEE1394 interface is considered as the most promising candidate to meet the demand.

[0007]

In order to connect the digital output of a DVD video player (recorder) to a DTV,
The format must be acceptable to the DTV. Also, there is a demand for realizing transmission over the IEEE 1394 interface at the lowest possible cost. On the other hand, there is also a demand for transmitting the digital output of a DVD player (recorder) with the highest possible quality. A transmission mechanism that satisfies such conflicting requirements has not been put to practical use.

[0008] That is, if low cost is emphasized, transmission is performed at a low rate or low quality, but in this case, the high image quality of the DVD is sacrificed. On the other hand, if transmission is performed with high image quality, both the DVD and DTV need to support a high-rate interface. However, an interface corresponding to high-quality transmission (high-rate transmission) is expensive.

The present invention has been made in view of the above circumstances, and has as its object to provide a sender of digital information (source device,
Provided is a digital video / digital audio transmission method effective for realizing digital transmission between a DVD video player and its receiver (sink device, for example, a DTV) while satisfying high quality / low cost reciprocal conditions. It is to be.

[0010]

In order to achieve the above object, the present invention relates to a case where digital video data and / or digital audio data are multiplexed as an MPEG transport stream and transmitted via a serial interface. In the digital video / digital audio transmission method, a first parameter constraint on parameters of the digital video (encoding pixel size, encoding rate, etc.) and a second parameter restriction on parameters of the digital audio (sampling frequency, quantization bit number, etc.) Parameter constraint, the multiplexing parameter (multiplexing rate, for example, 1
A plurality of transmission levels (LD-1, LD-2, SD-) separately specified in association with at least one or more of the third parameter constraints relating to 9 Mbps or 26 Mbps.
1, SD-2, HD-1) (FIG. 3
ST104), the multiplexed (ST106 in FIG. 3) MPEG transport stream is transmitted (ST108 in FIG. 3).

Here, mutual confirmation between the devices that transmit and receive the MPEG transport stream (ST10 in FIG. 3).
0), the transmission level (LD-1, LD-1) is set such that the receiver of the MPEG transport stream can decode the transport stream without breakdown (that is, according to the device specifications of the receiver or the capability of the interface). −2, SD-1, SD-2, HD
-1) can be selected.

As the serial interface, I
An IEEE 1394 interface (or USB of a personal computer) can be used.

The digital video data is MPEG
Compressed video data can be used, and multiplexing of an MPEG transport stream can be used as the multiplexing method.

As the first parameter constraint, a constraint relating to a coding pixel size or a video coding rate can be used.

The first parameter constraint is MP ＠ ML
MPEG video profile level parameters that have the same pixel size as and allow a maximum coding rate higher than MP @ ML.

The MP having the same pixel size as the MP @ ML and allowing a maximum coding rate higher than the MP @ ML
At the transmission level including the restriction on the profile level of the EG video, transmission can be performed without using B pictures for digital video data.

[0017] The first parameter constraint can include a constraint that the video coding rate is up to about 24 Mbps.

Further, linear PCM data can be used as the digital audio data.

As the second parameter constraint, a sampling frequency of digital audio data, the number of quantization bits, and the like can be used.

As the third parameter constraint, a constraint on a multiplexing rate can be used.

As the multiplexing method, multiplexing of an MPEG transport stream can be used, and the third parameter constraint includes a constraint on a multiplexing rate of a maximum of about 19 Mbps or a maximum of about 26 Mbps. it can.

The serial interface (IEEE1)
394 and the like (source device and sink device) include information (FIGS. 4, 5, 7, 11, and 2) on the transmission level that can be reproduced by one device (source device).
3rd class LD-1, LD-2, SD-1, SD-2, HD
-1) can be set in a form that can be read from another device (sink device) or a system controller via the serial interface.

It is also possible to have a configuration in which delay information (see FIG. 7) representing video delay and audio delay is provided, and this delay report is read via the serial interface (IEEE1394 or the like). This delay information can include both the default value and the current value. (The distinction between the default value and the current value is "Low delay (LowDel
ay) "according to the content of the parameter.

By describing delay information of devices and exchanging them between devices (source device and sink device), delay adjustment can be performed. At this time, only the delay adjustment on the sink device side can be performed without adjusting the delay on the source device side, and a common value for video and audio can be used as delay information.

By adjusting the delay using the delay information, it is possible to prevent a timing shift (out of synchronization) between video and audio. That is, synchronization can be secured between different devices.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A digital video / digital audio transmission method according to an embodiment of the present invention and a digital video / digital audio transmission system using the method will be described below with reference to the drawings.

FIG. 1 is a block diagram for explaining the configuration of a system (a source device and a sink device connected via an MPEG transport stream) according to an embodiment of the present invention.

In this embodiment, digital video (video) data and digital audio (audio) data are multiplexed, and the multiplexed data is converted as an MPEG transport stream (MPEG-TS) to a DVD video player (source device). ) 200 to a digital TV (sink device) 300.

Here, the IEEE-TS serial transmission between the source device 200 and the sink device 300 includes the IEEE
An E1394 interface is used.

The transfer of AV data (audio / video data) by MPEG-TS can be performed by isochronous transfer (data is transmitted and received every 125 μs). In the format of the isochronous packet, a transfer destination ID is not given, but a channel number is given. That is, multiplexed MPEG-TS (AV data) via the isochronous channel
Is transferred.

When the source device 200 is a DVD video player, information recorded on the DVD video disk 100 is reproduced via a pickup system 202 as shown in FIG.

The reproduced data stream includes audio data (for example, a sampling frequency of 48 kHz,
Linear PCM audio with 16 quantization bits and 2 channels, video data (for example, NTSC interlaced video with an aspect ratio of 16: 9 encoded based on MPEG2), sub-picture data (subtitles or menu information, etc.) and navigation Data (information for menu highlight processing using sub-pictures, etc.)
It is included.

The various data in the reproduced data stream are divided by the demultiplexer 204 for each data type (audio data, video data, sub-picture data, navigation data) and transferred to the corresponding buffer.

That is, the audio data in the reproduced data stream is buffered by a first-in first-out (FIFO) type audio buffer 210, and an audio decoder 220
Is input to

The video data in the reproduced data stream is also buffered by a FIFO type video buffer 212 and input to a video decoder 222.

The sub-picture data in the reproduced data stream is buffered by the FIFO type sub-picture buffer 214 and input to the sub-picture decoder 224.
The navigation data in the reproduced data stream is buffered by the FIFO type navigation buffer 216 and input to the sub-picture decoder 224.

Information such as a menu selection operation by the user is input to the sub-picture decoder 224, and a menu highlighting process using highlight information in the navigation data is performed in response to the menu selection operation.

For example, when the user presses a menu button of a remote controller (not shown) attached to the DVD video player 200, a menu screen using sub-pictures is reproduced from the DVD video disc 100. From the menu screen display, select the audio language (English or Japanese, etc.)
The user selects the subtitle language (English or Japanese, etc.) and the presence / absence of subtitles through the key operation of the remote controller and the highlighting process.

Alternatively, from the display of the menu screen,
Type of audio data (2 of sampling frequency 48kHz)
Channel linear PCM audio, compressed multi-channel audio, or the like) is selected by the user through key operation of the remote controller and the highlighting process.

The image information such as subtitles and menus using such sub-pictures is supplied to a combining unit 232 by a graphical user interface (GU) corresponding to a user operation.
I) It is appropriately combined with the information from the processing unit 230.

The sub-picture information such as subtitles / menus and GUI information synthesized by the synthesizing unit 232 are input to the on-screen display (OSD) processing unit 234 as system information. In the OSD processing unit 234, the subtitle / menu / GUI information is superimposed on the video image as appropriate, and is input to the MPEG_TS multiplex encoder 250.

The multiplex encoder 250 further includes
The video information without the system information is supplied to the video decoder 222.
The audio information input from the menu and selected by the menu (or designated by default) is output from the audio decoder 220.
Is entered from

The MPEG_TS multiplex encoder 250 multiplexes input video information parameters (resolution, aspect ratio, etc.), audio information parameters (sampling frequency, number of quantization bits, number of channels, etc.) and input information. A transmission level is selected based on parameters to be performed (video information, audio information, multiplexing rate of system information, and the like) (the selection criterion is mainly based on the resolution of the video information).
This transmission level is selected by the MPU (system controller) 260.

Before selecting the transmission level, the MPU 260 selects the source device (DVD video player) 2
The type (specification) of the sink device (digital TV) 300 connected to 00 is previously confirmed via the IEEE 1394 interface. If the specifications of the sink device 300 are not known in advance, the sink device 30
This is because there is a possibility that a signal in a format in which 0 is accepted cannot be transmitted.

For example, if the sink device 300 is a model that does not support progressive (non-interlace) scanning,
The source device 200 cannot select the transmission level for transmitting the progressive scan video signal. Or,
If the sink device 300 sends a low-resolution video signal without knowing that it is a high-resolution compatible model, the high image quality of the sink device cannot be used.

Therefore, the MPU 260 checks the specifications of the sink device 300 in advance, and based on the input video information parameters, audio information parameters, and multiplexing parameters, the MPU 260 Is selected.

According to the transmission level thus selected,
The MPEG-TS multiplex encoder 250 multiplexes the input video information, audio information, and the like at a rate equal to or lower than the upper limit of the multiplex rate.

The multiplexed information (MPEG transport stream) is transmitted to the digital AV signal line DL via the IEEE 1394 interface 252. MPEG sent to digital AV signal line DL
-TS is transferred to the IEEE 1394 interface of the sink device 300.

The MPU 260 of the source device 200 reads the device ID from the internal memory of the sink device 300 via the digital line DL and the IEEE1394 interface.
Information and the like can be taken out. This device ID information is "I (sink device) is model A of company T
It is a digital TV called BC, and it is a model that supports the function of ..... "
00, the MPU 260 transmits multiplexed digital information (MPEG-T
S) can be sent.

If the sink device 300 does not have such device ID information, the MPU 260 operates at a (safest) level that can handle any sink device.
It can be configured to send PEG-TS. Sink device 30
If 0 is a high-performance model without such device ID information, the user directly notifies the MPU 260 of the grade of the sink device so that the MPEG-TS can be transmitted at an appropriate transmission level. Is possible.

FIG. 1 also shows an analog TV (sink device) 400 connected to a DVD video player (source device) 200 via a normal analog line AL. We do not use transmission levels properly.

FIG. 2 is a block diagram illustrating the configuration of a standard model 1000 of an MPEG transport stream decoder used in the system according to one embodiment of the present invention.

The encoder (250 in FIG. 1) that creates the MPEG-TS performs encoding so that the decoder created according to this standard model can decode the MPEG-TS without failure. The sink device 300 of FIG. 1 has a built-in decoder such as this standard model.

In FIG. 2, an MPEG-TS (eg, a stream in which linear PCM audio is multiplexed with MPEG2 video) sent from a source device (such as a DVD video player) is received by the IEEE 1394 I / F 1002.

The IEEE 1394 I / F 1002 converts the received MPEG-TS packet into a packet distributor 10
Send to 04. The packet distributor 1004 sends the audio information to the audio transport buffer TBa1010 and sends the video information to the video transport buffer TBv1012 based on the ID (PID; see FIG. 12) of the sent packet. Transfers information to the system transport buffer TBsys10
Send to 14.

In this embodiment, the buffer sizes of these transport buffers 1010 to 1014 are as follows:
Each has 512 bytes.

Audio transport buffer TB
From a1010, a PES (packetized elementary stream) of audio information is sent to the audio buffer Ba1020 at a rate Rxa. The size BSa of the audio buffer Ba1020 is selected to be 4KB (3584 bytes) in combination with the size of the buffer TBa (512 bytes).

From the audio buffer Ba1020,
ES (elementary stream) of audio information
It is sent to the audio decoder Da1040 at the rate Ra.

On the other hand, the video transport buffer T
From Bv1012, the PES of the video information has the rate Rx
v is sent to the video multiplexing buffer MBv1022.
Subsequently, the elementary stream ES of the video information is sent from the video multiplexing buffer MBv1022 to the video elementary stream buffer EBv1032 at the rate Rbxv. Then, from the video elementary stream buffer EBv1032 to the video decoder Dv1
The buffered video information ES is sent to 042.

Similarly, the PES of the system information is output from the system transport buffer TBsys1014 at the rate Rxsys and the system buffer Bsys1024.
Sent to Then, the system buffer Bsys102
4 to the system decoder Dsys 1044 at a rate Rs
The system information ES is sent in ys.

With the above configuration, each decoder 1040
The various information (audio information, video information, system information) multiplexed and transmitted to the MPEG-TS is transmitted to the internal circuit of the sink device from -1044.

By the way, the transport stream system target decoder T-STD (decoder standard model) for 2-channel linear PCM, except for the T-STD model parameter, has a TS-TS for MPEG audio.
Follow TD.

In FIG. 2, the packetized elementary stream PE from buffer 1010 to buffer 1020 is shown.
The rate of S is Rxa, and the rate of the elementary stream es from the buffer 1020 to the decoder 1040 is Ra. The size of the buffer 1020 is set to B
Sa. Here, it is assumed that the size of the multiplexing buffer (for audio) is BSmux, the buffer size of the audio decoder is BSdec, and the buffer size necessary for PES overhead is BSoh.

In this case, the T-STD model parameters for the linear PCM in the preferred embodiment of the present invention are as follows: * Rxa = 1.2 × 48 kHz × 2ch × 32 bits = 3,686,400 [bps] * Ra = 48 kHz × 2 ch × 32 bits = 3,072,000 [bps] * BSa = BSmux + BSdec + BSoh = 3,584 [bytes] To show specific numerical values for the buffer size, for example: BSmux = 0.004 sec × Ra = 1,536 bytes BSdec = 768 bytes BSoh = 16 bytes (PES header size) x 2 = 3
2 bytes 所 要 Required size of BSa = 1,536 + 768 + 32 =
2,336 [bytes] <3,584 [bytes]. According to the above numerical example, since the buffer size BSa of the audio buffer 1020 in FIG. 2 only needs to be 2,336 [bytes], BSa = 3,584 [bytes] in the linear PCM T-STD model parameter.
Will fully satisfy the requirements.

By the way, if the buffer size of the transport buffer 1010 in FIG.
Sa = 3,584 + 512 = 4094 [bytes] (= 4
k bytes), which is a good buffer size. In other words, the audio transport buffer 1010 and the audio buffer 1020 shown in FIG. 2 can be composed of one 4 kbyte buffer memory, which is economical.

As described above, the buffer size is set to IEC /
By specifying the same value as for MPEG audio specified in ISO 13818-1, at least MP
Receiving device (sink device) compatible with EG audio
In this case, there is no need to add a buffer capacity to reproduce 2-channel linear PCM audio.

The transport stream system target decoder T-STD (decoder standard model) for MPEG1 video / MPEG2 video is based on ISO / IE
It complies with the MPEG transport stream defined in C13818-1 (MPEG2 system), and also complies with the restrictions shown in the embodiments of the present invention.

Also, MPEG1 audio / MPEG2
T- for audio (ISO / IEC13818-3)
STD conforms to ISO / IEC13818-1 (MPEG2
System) and the restrictions described in the embodiments of the present invention.

Further, the T-STD model for PSI data complies with the MPEG transport stream defined by ISO / IEC13818-1 (MPEG2 system).

FIG. 3 is a flowchart for explaining the operation of the system according to the embodiment of the present invention.

Hereinafter, a description will be given on the assumption that the processing of this flowchart is executed by the MPU 260 of FIG.

First, the MPU 260 accesses the device ID information and the like of the sink device 300 via the IEEE 1394 interface, and checks what kind of device is to be connected (step ST100).

The device ID information can include, for example, the following information: ID = 0 → digital TV ID = 1 → set top box STB ID = 2 → DVD player ID = 3 → DVD recorder ID = 4 → Digital VCR ID = 5 → Switcher ID = 6 → Personal computer ID = 7 → Other video equipment with IEEE1394 interface Other information regarding the connected equipment can include, for example, the following information: Character code of manufacturer name Product serial number and / or version number For digital TV, compatible resolution / scanning frequency for video, compatible sampling frequency / quantization bit number / channel for audio Recording available for DVD recorder or digital VCR After checking the other party, such as the bit rate of the timer, the presence or absence of the timer recording function, the remaining capacity of the set recording medium, and the like, the MPU 260 obtains the reproduction output of the DVD video player (the content of the DVD disc 100 being reproduced at that time). Parameters of video information (resolution, compression method, etc.), parameters of audio information (sampling frequency, number of quantization bits, number of channels, etc.), and parameters of system information (sub-picture information, contents of navigation information) are detected (step ST10).
2).

Then, a transmission level is selected from the detection result (step ST104). For example, as a video parameter, a resolution of 720 × 480 (NTSC) /
MPEG2 · MP @ ML is detected, and a sampling frequency of 48 kHz / quantization bit number of 16 bits / 2-channel linear PCM is detected as an audio parameter.
When the partner device (sink device) corresponds to a maximum bit rate of 24 Mbps, “SD-2” is selected as the transmission level from the relationship illustrated in FIG.

The transmission level (SD-
2) and the upper limit of the multiplexing rate (for example, 26 Mbp)
s) At the following rate, video information and audio information (and system information such as sub-picture information as appropriate) reproduced from the DVD video disc 100 are multiplexed into an MPEG transport stream (step ST10).
6).

The multiplexed MPEG-TS is
The data is serially transmitted to a sink device (digital TV) by IEEE1394 via a predetermined isochronous channel (step ST108).

In the preferred embodiment of the present invention, the following levels are determined as some transmission levels: level LD-1: low-resolution video (SIF format); level LD-2: low-resolution video (commonly known) Half SD1); Level SD-1: Standard resolution TV; Level SD-2: Standard resolution TV with high bit rate; Level HD-1: High resolution TV (future extension).

A sink device such as a digital TV capable of receiving a bit stream corresponding to at least one of the plurality of levels has a capability of decoding or displaying any bit stream according to the level. And

On the other hand, it is assumed that a source device such as a DVD player capable of transmitting a bit stream corresponding to at least one of the plurality of levels has a capability of transmitting a bit stream according to the present invention.

As described above, a plurality of discrete levels (LD-
1, LD-2, SD-1, SD-2, HD-1), it is possible to provide a transmission system that satisfies various requirements regarding cost, image quality, and the like. Further, it is possible to easily determine whether connection between devices is possible with a small amount of information. Further, since the number of levels is limited to a finite number, the design of the corresponding device is also facilitated.

In particular, by exchanging information on the level corresponding to each device using the asynchronous (asynchronous) transfer mode of the IEEE 1394 interface, it is possible to determine the connection possibility between the devices and determine at what level the transmission is performed. Determination can be easily realized.

FIG. 4 shows transmission levels (LD-1, LD-2, and LD-2) used in the system according to the embodiment of the present invention.
SD-1, SD-2, HD-1) and a video format (NTSC system).

FIG. 5 shows transmission levels (LD-1, LD) used in the system according to the embodiment of the present invention.
2, SD-1, SD-2, HD-1) and other video formats (PAL).

As can be seen from these figures, a plurality of transmission levels (LD-1, LD-2, SD-1, SD-2,
HD-1) is divided mainly on the basis of resolution (horizontal size / vertical size) in both NTSC video and PAL video.

FIG. 6 is a diagram for explaining the relationship between the transmission level used in the system according to the embodiment of the present invention and the audio format (there is a difference depending on the sampling frequency, the number of quantization bits, the number of audio channels, etc.). It is.

The plurality of transmission levels (LD-1, LD-
2, SD-1, SD-2, HD-1) have the ability to decode or reproduce any audio data required in FIG. have.

On the other hand, a source device having the ability to transfer data at one of the above-mentioned levels has the ability to transfer audio data which is required in FIG.

In the audio format shown in FIG.
By making the transmission of linear PCM essential, compatibility between devices can be easily maintained even if any audio compression method appears in addition to various existing audio compression methods. In other words, no matter what type of compressed audio is devised in the future, once it is decoded (expanded or decompressed), it will return to data similar to linear PCM, so that compatibility can be easily maintained at the linear PCM level. Become.

Further, since only the two-channel linear PCM is essential, the necessary cost can be minimized.

The sampling rate is 48 kHz.
By requiring z and 44.1 kHz, it is possible to directly handle not only DVD video but also audio data of video CDs and music CDs.

Further, it has a high affinity with various sampling rates defined by DVD audio (a sampling rate of an integer ratio is used with various sampling rates defined by DVD audio), and a sampling rate on a transmission side is used. Conversion is also easy.

FIG. 7 shows transmission levels (LD-1, LD-2, LD-2) used in the system according to the embodiment of the present invention.
FIG. 3 is a diagram illustrating a relationship between SD-1, SD-2, and HD-1) and video elementary stream parameters.

In FIG. 7, MPEG2 · MP @ ML +
+ Is not defined by ISO / IEC. However, in a preferred embodiment of the present invention, the following is performed.

That is, the maximum video bit rate for MP @ ML ++ has an upper limit of 24 Mbps, and other parameters comply with MP @ ML. In this case, "prof" of the sequence header for MP @ ML ++
The “ile_and_level_identifier” field indicates that MP @ H-
It is set to 14.

At the SD-2 level in FIG.
A profile level called MP @ ML ++ is prepared which has the same pixel size as ML and allows a maximum coding rate higher than MP @ ML.

Thus, if the MPEG encoding (encoding) is performed using the I, P, and B pictures, it is possible to perform transmission with higher image quality than normal (SD-1 level).

Further, sufficient image quality can be obtained even when encoding and transmission are performed with only I pictures or only I / P pictures.

At this time, when encoding is performed using only IP pictures, reordering (permutation) of pictures is not required, and motion search in the reverse direction is not required.

Further, when encoding is performed using only I pictures, no motion search / motion compensation is required at all.
The processing is greatly simplified, and the cost of encoding for transmission can be significantly reduced.

Also, when encoding with only I pictures,
By reducing the variation in the number of coding bits for each picture,
It is possible to reduce the amount of transmission / reception delay based on the VBV (Video Buffering Verifier) model, and it is possible to prevent an increase in the amount of delay due to frame rearrangement by not using B pictures.

In particular, in MP @ ML ++, by setting the maximum encoding rate to 24 Mbps, it is possible to transmit with sufficient image quality even when encoding (encoding) using only I-pictures, and at the decoding (decoding) side. Can be minimized.

FIG. 8 is a diagram for explaining the relationship between the transmission level and the audio elementary stream parameters used in the system according to one embodiment of the present invention.

This figure shows that at all transmission levels for audio, the sampling frequency 48 kHz /
This shows that the linear PCM has 44.1 kHz, 16 quantization bits, and 2 channels.

The other compression methods (AC-3, etc.), other sampling frequencies (96 kHz, etc.), other quantization bit numbers (20 bits, etc.), and other channel numbers (up to 8) depend on the source device and the sink device. It is treated as an optional item that can be determined by negotiation (exchange with the other party confirmation) between them.

FIG. 9 is a diagram for explaining a raw audio data format used in the system according to the embodiment of the present invention.

FIG. 10 is a view for explaining the contents of VBL (effective bit length code) in FIG.

This raw audio data format is composed of an 8-bit label including VBL in FIG. 10 and a sample word of up to 24 bits for each audio channel.

The sample word can be selected from 16 bits, 20 bits or 24 bits, and which bit number is adopted is determined by the effective bit length code V shown in FIG.
It is specified by the content of BL (2 bits).

By providing this VBL for each channel, for example, in a 5-channel multi-audio system having three front channels and two rear channels, the front three channels can be made 24-bit words and the rear two channels can be made 16-bit words. (If some of the multi-channel audio is set to relatively low bits, the proportion of the multiplex bit rate consumed by the audio can be reduced, and the bit rate of the video can be increased (that is, the image quality can be increased). be able to.

FIG. 11 shows transmission levels (LD-1, LD-) used in the system according to one embodiment of the present invention.
2, SD-1, SD-2, HD-1) and the parameter restrictions of the transport stream.

Here, it is assumed that at least one video stream or audio stream is multiplexed.

At each level of LD-1, LD-2, and SD-1, the maximum transport rate is set to 19 Mbps, which is lower than the transport rate of ATV (Advanced TV) in the United States. In the SD-2, the maximum transport rate is set to 26 Mbps, which is the same as the maximum transport rate in Japanese digital TV. By doing so, it becomes possible to increase the affinity with the existing digital broadcast receiver.

In addition, for each transmission level, the transmission bit rate can be freely determined within a limited range at the start of transmission. This makes it possible to efficiently utilize the bandwidth of the transmission path.

Even when the transmission path is in a state where there is no margin (congestion state) due to the influence of data transfer between other devices, A / V data can be transmitted by selecting a low rate. In addition, when there is a margin in the transmission band, high image quality transmission becomes possible by selecting a high bit rate.

[0115] Also, by making it possible to multiplex a plurality of audio streams, it is possible to simultaneously reproduce audio on a plurality of devices by multicast transmission. For example, a TV reproduces 2-channel linear PCM audio, and another digital audio amplifier connected to the same IEEE 1394 bus can reproduce multi-channel compressed audio data.

Here, when the linear PCM data and the multi-channel compressed audio data are transmitted independently and simultaneously,
DTCP (Digital Transmission Content Protectio)
It is necessary to have two systems for device authentication and encryption based on n) and the like, and for isochronous transmission processing of IEEE1394, which requires a significant increase in cost on the transmission side.

On the other hand, if all data necessary for the same transport stream are multiplexed and transmitted as in the embodiment of the present invention, the above processing can be realized by one system, and the cost on the transmitting side is increased. Can be prevented.

The minimum transmission rate is 1.5M.
By using bps, it is possible to clarify design constraints such as the buffer size and delay amount of the receiver and the burst size of data transfer, and it is possible to easily guarantee interconnectivity. In addition, the transmission rate is set to 1.5 Mbp.
Even if the transmission speed is reduced to s, transmission with image quality comparable to that of a video CD can be guaranteed.

FIG. 12 is a diagram for explaining assignment of a packet ID (PID) used in the system according to one embodiment of the present invention.

This PID is the PAT_PID assigned to the program association unit (see FIG. 15).
PMT_PID assigned to the transport stream program map unit (see FIG. 16) and PCR_P assigned to the program clock reference
ID (see the inside of the table in FIG. 16), VIDEO_PID assigned to video (see FIG. 17), and AUDIO assigned to audio streams for 8 channels.
_1_PID to AUDIO_8_PID and a null packet as stuffing (padding) for fixing the bit length.

In the PID of FIG. 12, 0x10 to 0
By prohibiting use up to x3F, it is possible to avoid contention with PID defined privately in digital broadcasting and the like.

FIG. 13 shows the contents of the audio stream type used in the system according to the embodiment of the present invention.

In FIG. 13, AC-3, DTS, S
Stream types for DDS and linear PCM are defined using a user-defined area (here, 81h to 84h). This stream type makes it possible to identify existing (or future) various audio data formats.

FIG. 14 shows allocation of stream IDs used in the system according to one embodiment of the present invention.

In FIG. 14, AC-3, DTS, S
By assigning stream IDs for DDS and linear PCM to private streams, MPEG1 / MP
EG2 video and MPEG1 / MPEG2 audio stream ID.

As described below, the structure for identifying a stream to be transmitted using the PAT and the PMT enhances the commonality of processing with a digital TV. In addition, since the private header and the sub-stream ID are not used, all information can be understood in the MPEG-TS layer. Essentially, the necessary stream is separated in the MPEG-TS layer using the PID. It is possible to do.

FIG. 15 shows a format of a program association unit (PAT) used in the system according to one embodiment of the present invention.

This PAT is the PID of the program map.
(Corresponding to PMT_PID in FIG. 12).

FIG. 16 shows a format of a transport stream program map (PMT) used in the system according to one embodiment of the present invention.

The PMT includes the DVD descriptor shown in FIG. 23, the video elementary stream information shown in FIG. 17, and the audio elementary stream information shown in FIG.

FIG. 17 shows a format of video elementary stream information used in the system according to one embodiment of the present invention.

This video elementary stream information includes the stream type (02h) in FIG. 13 and the video PID (0010h-1FFEh) in FIG.

FIG. 18 shows a format of audio elementary stream information for linear PCM used in the system according to one embodiment of the present invention.

The linear PCM audio elementary stream information includes stream type (82h) (FIG. 13), audio_x_PID (x is audio stream number 1 to 8) (FIG. 12), and linear PCM audio stream descriptor (FIG. 24). Contains.

FIG. 19 shows a format of AC-3 audio elementary stream information used in the system according to the embodiment of the present invention.

The audio elementary stream information for AC-3 has a stream type (81h) (FIG. 1).
3), audio_x_PID (x is audio stream number 1 to 8) (FIG. 12), variable bit length AC-3
An audio stream descriptor (based on the ATSC standard) is included.

FIG. 20 shows a format of elementary stream information for MPEG audio used in the system according to one embodiment of the present invention.

The MPEG audio elementary stream information includes stream type (03h, 04h or 0Fh) (FIG. 13), audio_x_PID (x
Include audio stream numbers 1 to 8) (FIG. 12).

FIG. 21 shows a format of DTS audio elementary stream information used in the system according to one embodiment of the present invention.

The DTS audio elementary stream information has a stream type (83h) (FIG. 1).
3), audio_x_PID (x is audio stream number 1 to 8) (FIG. 12), and includes a variable bit length DTS audio stream descriptor.

FIG. 22 shows a format of audio elementary stream information for SDDS used in the system according to one embodiment of the present invention.

This audio elementary stream information for SDDS has a stream type (84h) (FIG. 1).
3), audio_x_PID (x is audio stream number 1 to 8) (FIG. 12), SDDS of variable bit length
An audio stream descriptor (based on the ATSC standard) is included.

FIG. 23 is a view for explaining the contents of a DVD descriptor used in the system according to one embodiment of the present invention.

A DVD descriptor has an 8-bit descriptor tag, an 8-bit descriptor length, and an 8-bit descriptor tag.
It consists of a bit transmission level and an 8-bit future extension area.

[0145] DVD Descriptor is PMT (Fig. 16)
In the MPEG-TS layer, it is understood that this MPEG-TS is a stream from a DVD, and the level (LD-1, LD-
2, SD-1, SD-2, HD-1).

FIG. 24 shows the contents of the linear PCM audio stream descriptor used in the system according to one embodiment of the present invention.

The linear PCM audio stream descriptor having the contents as shown in FIG.
In the MPEG-TS layer, information such as the sampling frequency and the number of quantization bits of the audio stream can be known. That is, it is possible to obtain all information necessary for audio reproduction without analyzing the elementary stream ES or the packetized elementary stream PES, and it is possible to reduce the cost on the reproduction side.

The format of the AC-3 audio stream descriptor conforms to the US ATSC standard. In this case, the descriptor tag for the AC-3 audio stream descriptor is 81h.

FIG. 25 is a view for explaining the contents of restricted multiplexing parameters for the two-channel linear PCM used in the system according to the embodiment of the present invention.

In MPEG2 video and MPEG1 video, the format of packetization and multiplexing is as follows.
ISO / IEC13818-1 (MPEG2 system)
In addition to the MPEG transport stream defined in the above, and also according to the restrictions described in the embodiments of the present invention.

The PES format for the two-channel linear PCM must follow the restrictions shown in FIG.
However, in the embodiment of the present invention, the MPEG transport stream standard (ISO / IEC13813) is used.
Except for the restrictions specified in -1), no restrictions are placed on the multiplexing format for transport stream packets.

P of 2-channel linear PCM audio
The processing is facilitated by making the ES packet a fixed length, and by having two access units fixedly contained in one PES packet.

By fixing the PES length and the PES header length, the PES generation on the transmitting side and the PES on the receiving side are performed.
S decryption becomes easy, and it becomes possible to reduce costs on the transmission side and the reception side, respectively. In addition, since the audio access unit and the PES are aligned, the affinity with the reproduction process of the data after the PES decoding on the reproduction side is high, and the design cost on the reproduction side can be reduced.

By defining the audio access unit by the number of samples, the data size can be fixed regardless of the difference in sampling rate. Also, the interval between the access units is about 2 milliseconds, and interrupt processing by software is possible.

By setting the PES size within 2 kbytes, processing in PES units can be performed with a small buffer amount, and the overhead of PES is reduced by 1%.
It is possible to hold down to the extent.

By setting the audio access unit size to 768 bytes, which is the same as the MPEG2 AAC access unit, compatibility with MPEG2 audio can be improved and the design cost on the receiving side can be reduced.

Further, by not limiting the length of the TS packet header, additional information can be multiplexed in the TS header such as PCR data. The PES size is 1552
When 1 PES is mapped to 9 TS packets due to the byte, 104 per 9 TS packets
It is possible to secure a byte additional information area. In this case, the multiplexing overhead including the PES and the TS can be suppressed to about 10%.

FIG. 26 shows that the sampling frequency is 48 kHz.
FIG. 3 is a diagram illustrating a typical transport format for two-channel linear PCM in the case of z.

In this format, linear PCM data for two channels has a fixed length (192 samples / 1536).
Byte), and a PES header (14 bytes) and a stuffing byte (2 bytes) are added thereto to form a PES payload for 2-channel linear PCM data. This PES payload is mapped to a plurality (here, nine) of transport streams TS. 9 TS
The portion less than the packet is filled by providing a stuffing byte (104 bytes in this case) in the first packet among the nine TS packets.

Each of the nine TS packets has a 4-byte T
It is composed of a TS payload (184 bytes) having an S header. The one obtained by removing the TS header from each TS payload corresponds to the PES packet of the PES payload for 2-channel linear PCM data.

In the example of FIG. 26, the PES header and the TS
The multiplexing overhead including both headers is estimated to be about 10%.

Although not shown, the audio TS packet of FIG. 26 may be interleaved with other TS packets.

FIG. 27 shows the contents of the PES header of the transport format for 2-channel linear PCM used in the system according to one embodiment of the present invention.

In MPEG1 audio and MPEG2 audio, the format of packetization and multiplexing conforms to the MPEG transport stream specified by ISO / IEC13818-1 (MPEG2 system), and also conforms to the restrictions described in the embodiments of the present invention. Obey.

In the above description, the case where IEEE 1394 is used for transmitting the multiplexed MPEG transport stream has been described. For this transmission, a serial transmission system (USB or the like) used in a personal computer is used. Can also.

In the above description, the specifications of the parameters of the audio / video data output from the DVD video player / recorder via IEEE1394 are described. Also, the transport syntax for data transfer,
Standard model parameters and detailed parameter constraints are also described.

By using the IEEE 1394 interface, it is possible to connect the output of a DVD player to a DTV, for example, with a single cable without separately connecting a video cable and an audio cable, thereby realizing high-speed and real-time digital video. And digital voice transmission.

In a preferred embodiment of the present invention, the IEEE
Based on E1394, isochronous transmission (IEC6
1883-1) and a transport stream (IEC61883-4) on IEEE1394.
An MPEG transport stream (ISO / IEC13818-1) is further added to the protocol stack.
The MPEG-TS is multiplexed with MPEG2 video, linear PCM audio (optionally compressed audio is also possible) and the like adopted in DVD video. The protocol stack above the IEEE 1394 base is provided with a copyright protection function for digital information.

[0169] Options for compressed audio and the like should be appropriately selected in accordance with mutual confirmation between the source device (DVD video player or the like) and the sink device (digital TV or the like) (what kind of device is the other party's specification). Can be.

The MPEG transport stream (MP
By using transmission based on (EG-TS), the commonality with digital broadcasting that also uses MPEG-TS is enhanced, and the format is easy to accept for digital TV.

A general MPEG-TS is defined by IEEE.
The method for transmission over 1394 is already known as IEC61
883-4. Furthermore, by using the widely used MPEG as a base, expandability and
Greater flexibility.

Further, by adopting the MPEG video, it is possible to perform high-quality transmission at a low bit rate. In addition, by supporting compressed audio as an option, high compression can be achieved similarly, and the transmission band can be effectively used.

Further, by defining the restrictions up to the MPEG-TS, it is possible to transfer AV data based on the method of the present invention even in another transmission system (such as USB used in personal computers and the like). Become.

[0174]

As described above, according to the digital video / digital audio transmission method of the present invention, the sender of digital information (source device, for example, a DVD video player) and its receiver (sink device, for example, a DTV) During the digital transmission while satisfying the reciprocal condition of high quality / low cost.

[Brief description of the drawings]

FIG. 1 shows a system (MP) according to an embodiment of the present invention.
Block diagram illustrating the configuration of a source device and a sink device connected via an EG transport stream);

FIG. 2 is a block diagram illustrating the configuration of a standard model of an MPEG transport stream decoder used in the system according to the embodiment of the present invention;

FIG. 3 is a flowchart illustrating the operation of the system according to the embodiment of the present invention;

FIG. 4 shows transmission levels (LD-1, LD-2, SD-1, S-1) used in the system according to the embodiment of the present invention.
D-2, HD-1) and video format (NTSC
Diagram illustrating the relationship with

FIG. 5 shows transmission levels (LD-1, LD-2, SD-1, S-1) used in the system according to the embodiment of the present invention.
D-2, HD-1) and other video formats (PAL
Diagram illustrating the relationship with

FIG. 6 is a view for explaining the relationship between the transmission level and the audio format (there is a difference depending on the sampling frequency, the number of quantization bits, the number of audio channels, etc.) used in the system according to the embodiment of the present invention;

FIG. 7 shows transmission levels (LD-1, LD-2, SD-1, S-1) used in the system according to the embodiment of the present invention.
D-2, HD-1) and a diagram for explaining the relationship between the video elementary stream parameters;

FIG. 8 is a view for explaining a relationship between a transmission level and an audio elementary stream parameter used in the system according to the embodiment of the present invention;

FIG. 9 illustrates a raw audio data format used in the system according to the embodiment of the present invention;

10 is a view for explaining the contents of VBL (effective bit length code) in FIG. 9;

FIG. 11 shows transmission levels (LD-1, LD-2, SD-1, and SD-1) used in the system according to the embodiment of the present invention.
Diagram explaining the relationship between SD-2, HD-1) and transport stream parameter restrictions;

FIG. 12 is a view for explaining assignment of a packet ID (PID) used in the system according to the embodiment of the present invention;

FIG. 13 is a view for explaining the contents of a stream type used in the system according to the embodiment of the present invention;

FIG. 14 is a view for explaining assignment of stream IDs used in the system according to the embodiment of the present invention;

FIG. 15 is a view for explaining a format of a program association unit used in the system according to the embodiment of the present invention;

FIG. 16 is a view for explaining a format of a transport stream program map unit used in the system according to the embodiment of the present invention;

FIG. 17 is a view for explaining a format of video elementary stream information used in the system according to the embodiment of the present invention;

FIG. 18 is a view for explaining a format of linear PCM audio elementary stream information used in the system according to the embodiment of the present invention;

FIG. 19 is a diagram illustrating a format of AC-3 audio elementary stream information used in the system according to the embodiment of the present invention;

FIG. 20 is a view for explaining the format of MPEG audio elementary stream information used in the system according to the embodiment of the present invention;

FIG. 21 is a view for explaining a format of DTS audio elementary stream information used in the system according to the embodiment of the present invention;

FIG. 22 is a view for explaining a format of audio elementary stream information for SDDS used in the system according to the embodiment of the present invention;

FIG. 23 is a view for explaining the contents of a DVD descriptor used in the system according to the embodiment of the present invention;

FIG. 24 is a view for explaining the contents of a linear PCM audio stream descriptor used in the system according to the embodiment of the present invention;

FIG. 25 is a view for explaining contents of constrained multiplexing parameters for the two-channel linear PCM used in the system according to the embodiment of the present invention;

FIG. 26 shows a case where the sampling frequency is 48 kHz;
A diagram for explaining a typical transport format for the channel linear PCM;

FIG. 27 is an exemplary view for explaining the contents of a PES header of a transport format for 2-channel linear PCM used in the system according to the embodiment of the present invention;

[Explanation of symbols]

100 DVD video disc; 200 DVD video player (source device); 202 DVD pickup system; 204 demultiplexer; 210-216 FIFO buffer; 220 audio decoder; 222 video decoder; 230: Graphical user interface processing unit; 232: Synthesizing unit; 234: On-screen display processing unit; 240: Audio DAC; 242: Video DAC; 244: Analog AV signal input / output interface; 250: MPEG transport stream multiplex encoder; 252: Digital AV signal input / output interface (I
260: System controller (MPU for device confirmation, parameter setting, etc.); 300: Digital TV (sink device using MPEG-TS); 400: Analog TV (sink device not using MPEG-TS); AL: Analog AV signal line; DL: Digital AV signal line (IEEE 1396); 1000: Standard model of MPEG transport stream decoder; 1002: I / O of MPEG transport stream
F; 1004: packet distributor (filter using packet ID); 1010: audio transport buffer TB
a; 1012 ... video transport buffer TBv; 1014 ... system transport buffer TBsy
s; 1020: audio buffer Ba (size BSa); 1022: video multiplex buffer MBv (size MBS)
v); 1024... system buffer Ba (size BSsy)
s); 1032... video elementary stream buffer E
Bv; 1040 audio decoder Da; 1042 video decoder Dv; 1044 system decoder Dsys.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference)

Claims (1)

[Claims] 1. A method in which at least one of digital video data and digital audio data is multiplexed as an MPEG transport stream and transmitted via a serial interface, wherein: a first parameter constraint relating to a parameter of the digital video; A second parameter constraint on digital audio parameters, a third parameter on the multiplexing parameters;
Based on any of a plurality of separately defined transmission levels associated with at least one or more of the parameter constraints
A video / audio data transmission method, comprising transmitting the multiplexed MPEG transport stream.