JP2003018210A - Data transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain synchronization with other media data while sending a specific kind of media data synchronously with a transmission line clock even in the case that the transmission band of multimedia data to be transmitted is made narrower than desired. SOLUTION: A separation part 3 separates contents 6 stored in a storage part 2 into media data 7a to 7c and outputs only media data 7a, which needs to be outputted synchronously with the transmission line clock, to a dummy data insertion part 4. In the case that the next media data 7a is already sent to the dummy data insertion part 4 from the separation part 3, the dummy data insertion part 4 transfers the media data 7a to a multiplexing part 5, but in the case that it is not sent there, that is, the multiplexing part 5 is multiplexing and transmitting other media data 7b and 7c still, the dummy data insertion part 4 generates dummy data to transfer it to the multiplexing part 5 instead of media data 7a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device for transmitting plural kinds of multimedia data such as digitized video data, audio data and general-purpose data.

[0002]

2. Description of the Related Art For example, a video server that delivers multimedia data such as video and audio via a fixed band transmission line should be transmitted in advance so that the output data rate does not exceed the band of the transmission line. Create media data.

Particularly, in an audiovisual terminal complying with ITU-T Recommendation H.324, etc., since the audio data is decoded in synchronization with the transmission path clock of the transmission path, that is, the network clock of the network, the video server transmits the data. It is necessary to transmit audio data in synchronization with the road clock.

[0004]

[Problems to be Solved by the Invention] However, ITU-T Recommendation H.3
In communication between terminals conforming to 24, since the multiplexing format is determined by negotiation between terminals and control information is sent during communication, even if a fixed bandwidth transmission line is used, the multiplexing format Due to the difference and the control information, the transmission band given to the net multimedia data may not be constant.

Therefore, if the transmission band required by the multimedia data to be transmitted cannot be secured, the multimedia data may not be transmitted from the video server at a desired timing.

In such a case, if the multimedia data is still sent, the multimedia data arrives at the receiving terminal with a little delay from the desired timing, and at the receiving terminal side, the voice data is sent at a clock slower than the transmission line clock. However, there is a problem in that there is no audio data to be reproduced when the decoding / reproducing operation is performed with the transmission path clock.

There is also a problem that if only audio data is transmitted in synchronization with the transmission path clock, reproduction synchronization with other media data is lost.

The present invention has been made to solve the above-mentioned problems, and even if the transmission band of multimedia data to be transmitted becomes smaller than the desired band, it is synchronized with the transmission line clock of the transmission line. It is an object of the present invention to provide a data transmission device capable of transmitting specific media data such as audio data and maintaining synchronization with other media data.

[0009]

In order to solve the above-mentioned problems, according to the present invention, in a data transmitting apparatus for packetizing and transmitting a plurality of types of media data, dummy data is inserted only in a specific type of media data for transmission. It is characterized by doing.

In particular, it is characterized in that the dummy data is inserted so that the synchronization between the specific type of media data and the other media data is maintained.

Further, the dummy data is inserted when the specific type of media data cannot be transmitted at a predetermined transmission timing.

Further, the specific media data in which the dummy data is inserted is audio data.

Further, the dummy data is data obtained by encoding silent data.

The dummy data is data obtained by coding background noise data.

Further, the dummy data is the same as the immediately preceding audio frame data.

Further, the dummy data is control data indicating silence.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. 1 is a configuration diagram showing a data transmission device according to a first embodiment of the present invention.
In the figure, 1 is a data transmission device of the present invention, 2 is a storage unit that stores content for distribution, 3 is a separation unit that separates the stored content for each media, and 4 is dummy data in the media data. A dummy data insertion unit to be inserted, 5 is a multiplexing unit that multiplexes each media data into one stream, 6 is content for distribution, and 7a to 7a.
Reference numeral c is media data in which the content 6 is separated for each medium such as audio, video, and data, and 8 is a multiplexed stream in which the media data 7 is multiplexed into one stream. Although only one dummy data insertion unit 4 is shown in the first embodiment, a plurality of dummy data insertion units 4 may of course be provided. Also, the types of media data 7a to 7c to be multiplexed are not limited to three types, and may be two types or more than three types.

Next, the operation will be described. The data transmission device 1 communicates with a communication terminal (not shown) via a network. At that time, the data transmission device 1 reads the content 6 stored in the storage unit 2, and then the separation unit 3
Is separated into media data 7a to 7c for each media.
At this time, the separated media data 7b and 7c are directly output to the multiplexing unit 5, while the media data 7a that needs to be output in synchronization with the transmission path clock, that is, the network clock is the dummy data insertion unit 4 Is output to the multiplexing unit 5 via. The media data 7a that outputs data in synchronization with the transmission path clock is data that must be decoded and reproduced in synchronization with the network clock on the receiving side, and examples thereof include audio data.

The multiplexing unit 5 reads the media data 7a from the dummy data inserting unit 4 at a constant cycle in synchronization with the clock of the transmission path, and the multiplexing unit 5 directly reads the other media data 7b and 7c from the demultiplexing unit 4. And multiplex and send. At this time, the dummy data insertion unit 4 causes the next media data 7
If a has already been sent from the demultiplexing unit 3, the media data 7a is passed to the multiplexing unit 5, but if it has not been sent, that is, the multiplexing unit 5 is still in synchronization with the previous media data 7a. When other media data 7b and 7c that need to be transmitted are multiplexed and transmitted, dummy data is generated instead of the next media data 7a and passed to the multiplexing unit 5.

That is, in the multiplexing unit 5 of the first embodiment, the transmission of the media data 7b and 7c is performed at the time when the media data 7a or the dummy data is not transmitted. That is, the multiplexing unit 5 uses the media data 7
The media data 7b and 7c are multiplexed in a band in which a or dummy data is not multiplexed.

Here, a concrete example of the dummy data will be explained. When the media data 7a which has to be decoded and reproduced in synchronization with the network clock is voice data, for example, in a call, generally, the silent time is shorter than the voiced time. Is long,
As the dummy data, silence data or encoded background noise data can be used. If you do this,
It is less likely that you will notice that the dummy data has been inserted, and you can talk smoothly.

The voice coded data immediately before the dummy data is inserted may be used as the dummy data. In this way, in the communication device on the receiving side,
Since the same voice as the previous voice will be repeated,
Even when background noise is heard, it is possible to reproduce a sound that is smooth enough not to notice that dummy data has been inserted.

Further, control data indicating that there is no valid voice data, that is, no sound may be transmitted as dummy data. If you do this,
This means that the amount of transmission data can be reduced as compared with the case of transmitting normal voice coded data.

In this way, the media data 7a such as audio data that must be decoded and reproduced in synchronization with the network clock can be output while including dummy data in synchronization with the transmission path clock. Also, the media data 7b and 7c will be transmitted according to the availability of the transmission path.

In the reading from the storage unit 2 by the separation unit 3, since the respective media data 7a to 7c are stored in the order in which they should be transmitted, only specific media data should not be read and should be transmitted. It is read in order.
Therefore, the transmission order of the media data separated by the separation unit 3 and read separately from the multiplexing unit 5 is substantially the same as the order of transmission.

FIG. 2 is a diagram showing the transmission timing of each piece of media data 7 in the multiplexed stream 8. Desired transmission timings T1, T2, T of the content 4 to be transmitted
3, ... are shown in (a), and transmission timings T1, T2, T3, ... And media data 7a to 7 when the transmission band, that is, the information rate, decreases in the same transmission order as in (a)
The shift of the transmission timing of c is shown in (b). further,
The transmission timing of the media data 7a to 7c realized in the first embodiment when the transmission band becomes small is shown in (c).

That is, in FIG. 2A, the media data 7a to 7c are in a state of being regularly transmitted. FIG. 2B shows that this content is transmitted in the same order when the transmission band, that is, the information rate is reduced.
Is.

FIG. 2B shows media data 7a to 7c.
Is sent periodically, the media data 7a is
Originally, the desired transmission timings T1 and T shown in FIG.
Unless transmitted at intervals of 2, T3, ..., the communication terminal that receives the multiplexed stream 8 runs out of media data 7a to be reproduced and decoded.

Therefore, desired timings T1, T2, T3, ... For transmitting the media data 7a shown in FIG.
I want to send media data 7a at the same timing as, but due to changes in the receiving specifications on the receiving terminal side and the communication environment, the information rate, that is, the transmission rate, is sufficiently secured as shown in FIG. 2 (b). If it becomes impossible and the transmission rate becomes smaller than that shown in FIG. 2A, for example, even when the desired timing T2 for transmitting the media data 7a2 has come, the reading of the media data 7c continues, and the next In some cases, the media data 7a2 cannot be read from the separation unit 3.

When such a situation occurs, the dummy data insertion unit 4 of the first embodiment generates dummy data and transmits it as shown in FIG. 2 (c).

That is, as shown in FIG.
When the desired timing T2 for transmitting the media data 7a shown in (a) comes, the reading of the media data 7c1 from the separation unit 3 continues, and the media data 7c is still being read.
If a2 cannot be read from the demultiplexing unit 3, the next media data 7a2 has not arrived, so the dummy data generation unit 4 generates dummy data instead of the media data 7a2 and outputs it to the multiplexing unit 5. .

Then, when the desired timing T2 for transmitting the media data 7a shown in FIG. 2 (a) comes, the multiplexer 5 causes the dummy data generator 4 to send the media data 7a.
Since the dummy data of a2 is input, the dummy data is preferentially multiplexed. Therefore, at the desired timing T2 for transmitting the media data 7a shown in FIG. 2A, the dummy data generator 4 causes the media data 7a to be transmitted.
Will be multiplexed.

Therefore, as shown in FIG. 2C, the media data 7a shown in FIG.
Media data 7a at the desired timing T2 for transmitting
Since the dummy data of 1 is preferentially inserted, the media data 7c1 is divided and transmitted.

As a result, the media data 7a or its dummy data is always multiplexed at the desired timing T2 for transmitting the media data 7a, and the synchronization with the other media data 7b and 7c is ensured. Although the media data 7a to 7c arrive at the receiving terminal side with a little delay from the desired timing, even if the media data 7a is decoded and reproduced by the transmission path clock, there is no possibility that the media data 7a to be reproduced does not exist. , The media data 7a is other media data 7b, 7
It is also possible to prevent the reproduction synchronization with c from being lost. That is, the desired timing T for transmitting the media data 7a
1, T2, T3, ..., Media data 7a or its dummy data is always multiplexed, and media data 7a, 7b, 7c to be synchronized, that is, media data 7a1, 7b1, 7c1, media data 7a.
2, 7b2, 7c2, media data 7a3, 7b3
7c3 ..., although the order of multiplexing may be slightly changed or the media data may be divided during the multiplexing, the media data 7a, 7b, 7c to be synchronized are grouped together, that is, multiplexed. Since the media data 7a, 7b, 7c is transmitted after being converted, the reproduction of the media data 7a and the reproduction synchronization with the other media data 7b, 7c are not lost although the transmission of the media data 7a, 7b, 7c is delayed.

Particularly, in an audiovisual communication terminal compliant with ITU-T Recommendation H.324, etc., since the audio data is decoded in synchronization with the transmission path clock, that is, the network clock, the audio data corresponds to the media data 7a. On the receiving terminal side, media data such as audio data and other video data arrives with a slight delay from the desired timing, but there is no audio data to reproduce even if the audio data is decoded and reproduced with the transmission path clock. Moreover, it is possible to prevent the audio data from being out of sync with the other video data.

Then, as shown in FIG. 2C, after the dummy data of the media data 7a is preferentially inserted at timing T2, the media data 7c1 is divided and transmitted, and the transmission of the media data 7c1 is completed. However, when the transmission of the media data 7a1 to 7c1 to be synchronized is completed, if there is time until the desired timing T3 for transmitting the next media data 7a, the media data 7a
Instead of transmitting 2, the media data 7b2 is transmitted.

Further, as shown in FIG. 2 (c),
Desired timing T for transmitting the next media data 7a
3 arrives, even if the transmission of the media data 7b2 that has been transmitted until then is not completed,
The transmission of b2 is stopped, and the media data 7a2 is preferentially multiplexed and transmitted. After the transmission of the media data 7a2, the remaining media data 7b2 is transmitted if any, and the transmission of the remaining media data 7b2 is terminated. Later, the media data 7c3 synchronized with these media data is transmitted. Of course, when the desired timing T4 for transmitting the next media data 7a comes during the transmission of the media data 7c3, as described above, the transmission of the media data 7c3 has not been completed, so the dummy data generation unit 4 , Dummy data is generated instead of the media data 7a3 and output to the multiplexing unit 5.

Therefore, the media data 7a or the dummy data thereof is preferentially multiplexed and transmitted at the desired timing synchronized with the transmission path clock, and the media data 7a or the dummy data thereof is transmitted at a time (band) during which the media data 7a is not transmitted. Media data 7b and 7c which should be synchronized with 7a are transmitted at an arbitrary timing in synchronization with the corresponding media data 7a.

Therefore, according to the first embodiment, only the media data 7a or its dummy data is transmitted with priority over the other media data 7b and 7c at a desired timing synchronized with the transmission path clock. The receiving terminal that receives the multiplex stream 8 has an effect that it can always receive the data of the media data 7a without excess or deficiency.

Further, in the first embodiment, when the transmission band is lower than the information rate of the content to be transmitted, the content is transferred slowly as a whole, for example, 10 minutes of content is changed to 12 minutes. However, since data is not discarded, all media data can be sent in synchronization, and dummy data should be used for audio media data that requires regular data. Therefore, it can be said that the content can be distributed without adversely affecting it.

Embodiment 2. In the first embodiment described above, each piece of media data was multiplexed in time series to be transmitted and accumulated as one content. However, an embodiment in which each piece of media data is accumulated next Will be described.

FIG. 3 is a block diagram showing the configuration of the data transmitting apparatus according to the second embodiment. In the figure, 2a,
Reference numerals 2b and 2c are storage units that store contents for the media data 7a to 7c, respectively. That is, in the first embodiment, unlike the data transmission device of the first embodiment shown in FIG. 1, a program composed of a plurality of media data 7a to 7c is stored in one storage unit 2 and the separation unit is used. 3, the respective media data 7a to 7c are stored in advance in the corresponding storage units 2a, 2
It is characterized by being stored in b and 2c. The rest of the configuration is similar to that of FIG.

Next, the operation will be described. The data transmission device 1 reads the contents stored in each of the three storage units 2a to 2c. However, timing information to be transmitted in order to synchronize media is added to the packet unit of media data of each content, and the media data is stored from the storage units 2a to 2c in the order of the timing to be transmitted. read out.

As a result, similar to the case of the first embodiment, only the specific media data is not read out, and the contents from the respective three storage units 2a to 2c are maintained while maintaining the synchronization for transmission between the media. The media data 7a to 7c can be read.

Then, only the media data 7a for which it is necessary to output the data in synchronization with the transmission path clock is input to the dummy data insertion section 4 as in the case of the first embodiment.

After that, as in the case of the first embodiment, the multiplexing unit 5 reads out the media data 7a from the dummy data insertion unit 4 at a constant cycle in accordance with the clock of the transmission path, multiplexes it, and transmits it. At this time, in the dummy data insertion unit 4, if the media data 7a to be transmitted has already been read from the storage unit 2, the media data 7a is passed to the multiplexing unit 5, and if it has not been transmitted, the dummy data insertion unit 4 substitutes the dummy data instead. Data is generated and passed to the multiplexing unit 5, and the multiplexing unit 5
For the media data 7b and 7c, the data read out when the media data 7a is not transmitted is transmitted. As a result, the media data 7a can be output in synchronization with the transmission path clock even though it includes dummy data, and the media data 7b and 7c are transmitted according to the availability of the transmission path. .

Further, since the media data 7a to 7c read out from the storage units 2a to 2c are data to be transmitted at substantially the same time, the media data 7a to 7c can be kept in synchronization.

Therefore, according to the second embodiment, the control is performed so that the data having similar transmission timing information values are always read from the respective storage sections 2a to 2c corresponding to the respective media data 7a to 7c, and the media data 7a or Since the dummy data is transmitted with priority over the other media data 7b and 7c at a desired timing synchronized with the transmission path clock, the media data 7a is always in excess and shortage as in the first embodiment. There is an effect that the media data 7a to 7c can be received and reproduced and the synchronization between the media data 7a to 7c can be maintained.

Incidentally, in the explanation of the first and second embodiments,
Audio data has been described as an example of the media data 7a to be transmitted at a predetermined transmission timing, but the present invention is not limited to this, and media data other than audio data may be used as long as it is media data to be transmitted at a desired timing. Good.

[0050]

As described above, according to the present invention, when a plurality of types of media data are packetized and transmitted, the dummy data is inserted only into a specific type of media data, so that, for example, If dummy data is inserted so that synchronization between the specific type of media data and other media data is maintained, multiple types of media data can be synchronized and multiple types of media can be received on the receiving side. Data can be played back synchronously.

Further, in particular, in the case where the media data of a specific type is media data such as audio data which is determined to be transmitted at a predetermined transmission timing, the media data of the specific type is determined in advance. By inserting the dummy data when transmission cannot be performed at the transmission timing, it is possible to prevent reproduction omission of a specific type of media data.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a data transmission device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a transmission timing of each media data 7 in the multiplexed stream 8 according to the first embodiment.

FIG. 3 is a block diagram showing a configuration example of a data transmission device according to a second embodiment.

[Description of Codes] 1 data transmission device, 2 storage unit, 3 separation unit, 4 dummy data insertion unit, 5 multiplexing unit, 6 distribution content, 7a to 7c media data, 8 multiplexed stream.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 7/24 (72) Inventor Yukinari Matsuda 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Sanryo Denki Co., Ltd. Inner F term (reference) 5C059 RB02 RC07 RC32 RE02 SS06 5C063 AB07 AC01 AC05 CA11 DA05 DA13 5K028 AA01 EE03 EE08 KK32 LL26 MM04 NN31 5K030 HA08 HB01 HB09 HB16 HB21 LC01 5K047 AA03 CC02 DD02 GG41

Claims (8)

[Claims] 1. A data transmitting apparatus for packetizing and transmitting a plurality of types of media data, wherein the data transmitting apparatus transmits dummy data only while inserting dummy data into a specific type of media data. 2. The data transmitting apparatus according to claim 1, wherein the dummy data is inserted so that the synchronization between the specific type of media data and the other media data is maintained. 3. The data transmitting apparatus according to claim 1, wherein the dummy data is inserted when the specific type of media data cannot be transmitted at a predetermined transmission timing. 4. The data transmission device according to claim 1, wherein the specific media data in which the dummy data is inserted is audio data. 5. The data transmission device according to claim 1, wherein the dummy data is data obtained by encoding silence data. 6. The data transmission device according to claim 1, wherein the dummy data is data obtained by encoding background noise data. 7. The data transmitting apparatus according to claim 1, wherein the dummy data is the same as the immediately preceding audio frame data. 8. The data transmission device according to claim 1, wherein the dummy data is control data indicating silence.