JP2002176434A - Video/audio data transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video/audio data transmission system that reduces an audio data quantity in the case of silence when compressed and multiplexed video and audio signals are transmitted and assigns the reduced data quantity to a transmission quantity of video data so as to transmit an image with higher image quality. SOLUTION: In the transmission system where video and audio signals are compressed, multiplexed and assembled into packets and the packets are transmitted, a transmission section is provided with a means that detects whether or not a received audio signal is a silence signal or a sound signal, multiplexes video compression data and audio compression data in the case of the sound signal, assembles the multiplexed data into packets, transmits the packets, and stops multiplexing and packet processing of the audio compression data for a period of silence, transmits audio packets having an ID code denoting the silence, assigns the transmission quantity equivalent to the period when the packet assembling is stopped to the transmission of the video compression data so as to increase the transmission quantity of the video compression data as its processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission apparatus for compressing, multiplexing and transmitting a video signal and an audio signal.

[0002]

2. Description of the Related Art Conventionally, audio signals and video signals have been
When data is compressed and multiplexed and transmitted using the -1 or MPEG-2 coding method, the data is transmitted using a transmission device as shown in FIGS. In the transmitting section Tx in FIG. 3, the video signal and the audio signal are converted into digital signals, and are compressed and encoded into compressed data by the video compressor 1 and the audio compressor 2, respectively. For example, a video signal is compressed by the MPEG-2 encoding method, and an elementary stream (ES: Eleme
ntary stream) signal, which is converted into a PES packet, and sent to the multiplexer 3. Here, PES stands for Pack
An abbreviation of etized Elementary Stream, which is packetized by adding header information to compressed data. The audio signal is compressed by the MPEG audio coding method to form an ES signal,
This is sent to the multiplexer 3 as a PES packet. The multiplexer 3 sends the transmitted video PES signal and audio PES signal.
The signal is time-division multiplexed to form audio and video TS (transport stream) packets for every 188 bytes of data, and a transmission unit output signal is generated. In the receiving unit Rx, the received TS is demultiplexed by the demultiplexing unit 4 into a video PES.
Signals and audio PES signals. The video PES signal is converted to an ES signal, and then converted to an MPEG-2 video decompressor 5.
, The data is expanded, and the video digital signal is extracted. Similarly, the audio PES signal is converted into an ES signal, then data is expanded by the MPEG audio intermediate unit 6, and an audio digital signal is extracted. FIG. 4 shows a packet structure of TS data transmitted from the transmission unit Tx to the reception unit Rx. A TS packet is a combination of a TS header and a video PES or a TS header and an audio PES, and the data amount of one TS is 188 bytes. For this reason, one PES is transmitted while being divided into several TSs. When multiplexing the video and the audio, the TS structure as shown in FIG. 4 is used.

[0003]

In such a conventional transmission system, for example, when there is no audio signal or when there is no sound, the data structure as shown in FIG.
After the S header, the PES and ES headers follow, and thereafter, “0” data continues according to the rate amount. The receiving unit Rx receives and decodes the data having the same bit rate regardless of whether the audio signal is sound or no sound. As described above, in a device that multiplexes and transmits an audio signal and a video signal, when it is not necessary to transmit the audio signal, or when the transmitted audio signal is silent, the same amount of sound as Sending data is useless. The present invention eliminates the above disadvantages, reduces the amount of audio data when there is no sound,
An object of the present invention is to increase the transmission amount of video data from the reduced data amount, thereby enabling higher quality image transmission.

[0004]

In order to achieve the above object, the present invention provides a transmission apparatus for compressing, multiplexing, packetizing and transmitting a video signal and an audio signal. A means for detecting whether there is sound or sound is provided. In the case of sound, the video compression data and audio compression data are multiplexed and packetized and transmitted. During the period of silence, the audio compression data is multiplexed. This is a video / audio data transmission system that stops packetization and transmits an audio packet having an ID code indicating silence. Further, a transmission amount corresponding to a period during which the multiplexing and packetization of the audio compression data is stopped is allocated to the transmission of the video compression data, and a process of increasing the transmission amount of the video compression data is performed. Also,
The receiving unit is provided with means for detecting the presence or absence of the ID code indicating silence. If the ID code is not present, the received audio compression data and video compression data are respectively decoded to detect the ID code. Then, the received audio packet having the ID code is decoded in accordance with the transmission bit rate, and the received video / audio data transmission is performed by seamlessly switching and decoding the received compressed video data having an increased transmission amount. It is a method. That is, a detection means for determining whether the audio signal is sound or no sound is added. If the sound signal is sound, the video compression data and the audio compression data are multiplexed and transmitted as in the related art, and the audio signal is transmitted. Is detected as silence, only the header is sent with the ID of silence added to the audio header, and "0" data is not sent. At this time, the remaining data is filled with meaningless stuffing data so that the data structure of the TS becomes 188 bytes. As a result, when there is no sound, the data amount of the audio is reduced, the reduced data amount is applied to the transmission of the video data, and the transmission amount of the video data is increased, so that higher-quality image transmission becomes possible.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is shown in FIG.
This will be described below using the block diagram of FIG. The analog video signal is converted into a digital signal, encoded into an ES signal by the MPEG-2 video compressor 1, further converted into a PES signal, and sent to the multiplexer 3. The analog audio signal is similarly converted into a digital signal, encoded into an ES signal by the MPEG audio compressor 2, further converted into a PES signal, and sent to the multiplexer 3. And multiplexer 3
Then, the video PES signal and the audio PES signal are time-division multiplexed, and become TS output data as a TS packet structure.
Here, when the audio signal is a sound, a normal MPEG
It operates in the form of compression multiplex transmission. When the silent audio detector 7 detects that the input audio signal is silent, the MPEG audio compressor 2 outputs the ES header or the PE header.
A silent ID mark is attached to the S header, and only the header is transmitted as a TS packet. At this time, the amount of voice transmission data is reduced. On the other hand, when receiving the information that the audio signal is silent, the MPEG-2 video compressor 1 performs a compression operation to increase the bit rate of the video data by the reduced data amount on the audio side. As described above, by increasing the data amount, transmission with higher image quality can be performed.

FIG. 2A shows a TS data structure when there is sound. In this case, each data has a TS header, and is packetized every 188 bytes.
Transmitted. FIG. 2B shows a TS data structure when there is no sound. In this case, only the audio PES header and the audio ES header are sent in the first audio packet (in this case, audio data A1) in which silence has occurred, and a silent ID mark is attached to one of the headers. This TS packet includes only the TS header, the audio PES header, and the audio ES header, and if the total data amount is less than 188 bytes, meaningless stuffing data is inserted.
Since the audio data A2, which is the next audio packet, is data that is not transmitted, this packet period is applied to the transmission of the video data V3. In the receiving unit Rx, when the audio data has sound, the received TS is separated into a video PES signal and an audio PES signal by the demultiplexer 4, and the MPEG-2 video expander 5 and the MPEG audio expander 6 respectively. It is converted into an ES signal and decoded. Here, when the silent ID detector 8 detects that the audio PES signal is silent data from the ID mark added to the header, this information is output to the MP.
This is transmitted to the EG-2 video expander 5 and the MPEG audio intermediater 6. The MPEG-2 video decompressor 5 controls the decoder buffer so that it can be switched seamlessly or operates after resetting the buffer once since the bit rate of the transmitted video data increases when there is no sound. To Upon obtaining the information of silence, the MPEG audio expander 6 expands the packet after adding the "0" data including the ES header to the audio ES header of the packet as long as it matches the audio bit rate. As described above, when the audio signal is silent, an ID mark indicating that the audio signal is silent is added to the header of the first audio packet that has become silent.
If the ID mark is detected by the receiving unit without decoding the audio data that is a series of “0” s, the data is decoded with “0” data that matches the bit rate. As a result, the amount of audio data that can be reduced when there is no sound can be applied to data transmission of a video signal, the bit rate of the video signal can be increased, and higher quality image transmission can be achieved.

[0007]

According to the present invention, when an audio signal is silent, an ID mark indicating that the audio signal is silent is added to the header of the first audio packet in which the audio signal is silenced. If the ID mark is detected by the receiving unit without being transmitted, the data is decoded with "0" data that matches the bit rate. In other words, when there is no sound, the amount of audio data is reduced, and the reduced data amount is applied to the transmission of video data to increase the transmission amount of video data, thereby enabling higher-quality image transmission.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a video and audio compression multiplex transmission apparatus according to the present invention.

FIG. 2 is a schematic diagram showing a TS packet structure when there is sound and when there is no sound in the present invention.

FIG. 3 is a block diagram showing the configuration of a conventional video and audio compression multiplex transmission apparatus.

FIG. 4 is a schematic diagram showing a TS packet structure of a conventional multiplexing method.

[Explanation of symbols]

1: MPEG-2 video compressor, 2: MPEG audio compressor, 3: multiplexer, 4: demultiplexer, 5: MPEG-2
Video decompressor, 6: MPEG audio decompressor, 7: no sound detector, 8: no sound ID detector.

Claims (3)

[Claims] In a transmission apparatus for compressing, multiplexing, packetizing and transmitting a video signal and an audio signal, a transmitting unit is provided with means for detecting whether the input audio signal is silent or sound. In the case of sound, the video compression data and the audio compression data are multiplexed and packetized and transmitted. During the period of silence, the multiplexing and packetization of the audio compression data is stopped, and an ID code indicating silence is provided. A video / audio data transmission system characterized by transmitting audio packets. 2. A process according to claim 1, wherein a transmission amount corresponding to a period during which the multiplexing and packetization of the audio compression data is stopped is assigned to the transmission of the video compression data, and a process of increasing the transmission amount of the video compression data is performed. A video / audio data transmission system characterized by the following. 3. The receiving unit according to claim 1, wherein:
A means for detecting the presence or absence of an ID code indicating the absence of the sound is provided, and when there is no ID code, the received audio compression data and video compression data are respectively decoded, and when the ID code is detected, Video and audio data, wherein the received audio packet having the ID code is decoded in accordance with a transmission bit rate, and the received video compressed data having an increased transmission amount is seamlessly switched and decoded. Transmission method.