CN1972408A - A data transmission method for mobile multimedia broadcasting system - Google Patents

Abstract

The invention relates to a data transmission method of a mobile multimedia broadcasting system, comprising the following steps: (1) dividing service channel data into a plurality of data units, and encapsulating the data units in data segments, and calculating the length of each data unit, The type of the data unit is recorded in the data segment header; (2) The data segment and other data to be transmitted are encapsulated in a service channel for transmission; (3) After the terminal receives the data segment, according to each data segment in the data segment header The length of the unit fetches each data unit for receiving or playing data. This method can improve data transmission efficiency, and realize more auxiliary data function applications such as subtitles, file downloads, and IP multicasting on the premise of satisfying clear audio and video.

Description

A data transmission method of a mobile multimedia broadcasting system

technical field

The invention relates to multimedia broadcasting technology, in particular to a method for transferring data in mobile multimedia broadcasting.

Background technique

Mobile multimedia broadcasting is a multimedia playback technology that has emerged in recent years. With a handheld terminal, you can watch TV while moving at high speed. The terminal receives the program list through the wireless protocol, and can select the channel it has the right to watch, so that it can receive the multimedia data of the selected channel, and realize watching TV on the mobile terminal.

The air data transmitted by the system is divided into different channels. The data of each channel includes three types: video, audio and data. The terminal can receive the relevant data, and realize the normal broadcasting of the TV through the player on the terminal.

The data is used to implement subtitles, pictures, file downloads, IP multicast and Electronic Program Guide (ESG) applications, and is an important supplement to the real-time video and audio streams in the broadcast network.

There are two existing data encapsulation methods:

(1) Transport stream TS mode. The TS protocol is one of the MPEG standards of the Moving Picture Experts Group. It transmits data, video, and audio in a fixed 188-byte packet.

(2) The Real-Time Transport Protocol (RTP) method is a method of transmitting data, video, and audio data on an IP network. The size of the packet is not fixed. The time stamp of each packet header is used to ensure the time synchronization of the playback, and the sequence number is used to ensure the packet. playback order.

These two methods have their own advantages and disadvantages. The RTP method can only be used on the IP network. Because the RTP header, UDP header and IP header are relatively large, the smaller each RTP packet, the greater the overhead, and it is not suitable for transmitting each packet. relatively small data. The size of the TS method is fixed, and a piece of data is divided into multiple TS packets for intermediate transmission. The last packet cannot be completely used up, and there is a large amount of filling information. The transmission efficiency of the TS method is relatively low, about 80% to 90%.

On the other hand, the wireless bandwidth that the service network can provide to each mobile terminal is very limited, and sufficient transmission rate is required to meet the clear display of the terminal, but the low data transmission efficiency will inevitably lead to a corresponding reduction in the actual transmission rate of audio and video data or The data that can be transmitted is reduced, and then the audio and video quality output by the mobile terminal is reduced or more subtitles, pictures, file downloads, IP multicast and electronic program list applications cannot be realized.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for transmitting data in mobile multimedia broadcasting, which can improve data transmission efficiency, and further realize more subtitles, pictures, file downloads, IP multicast and electronic program list applications.

The above-mentioned technical problem of the present invention is solved in this way, a kind of data transmission method of mobile multimedia broadcasting system is provided, it is characterized in that: mobile multimedia broadcasting system comprises a data segment when sending a channel, and described data segment comprises data segment head and multiple The data segment header includes the number of data units, the length of the data unit, and the type of the data unit, and then it is sent in the service channel allocated for the channel.

A data transmission method of a mobile multimedia broadcasting system, comprising the steps of:

(1) the service channel data is divided into a plurality of data units, and the data units are encapsulated in the data segment, and the length of each data unit and the type of the data unit are recorded in the data segment header;

(2) Encapsulate the data segment and other data to be transmitted in a service channel for transmission;

(3) After receiving the data segment, the terminal takes out each data unit according to the length of each data unit in the data segment header, and performs data reception or playback.

According to the method provided by the present invention, the data segment header further includes a check code.

According to the method provided by the present invention, the data unit type includes ESG, subtitle, file download or IP multicast.

According to the method provided by the present invention, the service channel data includes one or more of subtitles, files, IP multicast, and ESG

According to the method provided by the present invention, the channel data further includes a subframe header, and the subframe header includes the length of the subframe header and the length of the data segment.

According to the method provided by the present invention, the channel data may also include a video segment, and the sub-frame header may also include a video segment length and a video parameter set.

According to the method provided by the present invention, the channel data may also include an audio segment, and the subframe header may also include the length of the audio segment and an audio parameter set.

According to the method provided by the present invention, the subframe header further includes a check code.

A method for transmitting data in mobile multimedia broadcasting provided by the present invention encapsulates several data in one channel data, further improves the transmission efficiency by means of variable length, and can realize more subtitles and files under the premise of clear audio and video. Download, IP multicast and other functional applications.

Description of drawings

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

FIG. 1 is a schematic diagram of media stream transmission in a service channel. In the figure, service channel 1 includes subframe header, video segment, audio segment and data segment required by a complete channel.

FIG. 2 is a schematic diagram of the internal logical relationship of the data segments of the frame structure shown in FIG. 1 .

Detailed ways

First of all, the core of the method of the present invention is described: the data within a period of time will be encapsulated together to realize the transmission of data, including the following aspects:

(1) The channel data of one service channel is composed of subframe header, video segment, audio segment, and data segment. The data in the channel except video and audio are encapsulated in the data segment.

(2) The data segment includes a data segment header and multiple data units, and the data is divided and encapsulated in one or more data units.

(3) The data segment header records the attributes of each data unit, including: the length of each data unit, the type of data unit, and the check code of the data segment header.

(4) Each data unit can encapsulate data content and its attributes.

Further, illustrate the present invention to the encapsulation method of data, as shown in Figure 1, a business channel corresponds to a channel, and the data of a channel is to send data once in a fixed time interval, and the fixed time interval can be one second, or is the other time value. The video data in the service channel is encapsulated in the video segment, the audio data is encapsulated in the audio segment, and other data is encapsulated in the data segment, the data is divided into multiple data units, and the data units are encapsulated in the data segment. After receiving the data segment, the terminal takes out each data unit according to the length of each data unit in the data segment header, and performs data reception or playback.

The data of one channel includes a subframe header 10 , a video segment 11 , an audio segment 12 , and a data segment 13 . The subframe header 10 mainly contains some control information, which must be provided. The main contents of the subframe header 10 are: subframe header length, video segment length, audio segment length, data segment length, video parameter set, audio parameter set, time stamp, check code, etc. Wherein: the check code can verify the reliability of the subframe header information. Timestamps are used to guarantee the display time of data on the screen.

The video segment 11, the audio segment 12, and the data segment 13 are optional, and one or more of them may appear. Whether these three data segments appear can be judged from the corresponding control field in the subframe header 10.

As shown in FIG. 2 , the data segment 13 includes a data segment header 130 and N data units 131 , N can be changed, and the specific value of N is determined according to actual needs within a period of time.

The relevant information of the data unit 131 is described in the data segment header 130, and part of the content in the data segment header 130 is:

(1) The total number of data units.

(2) The length of each data unit.

(3) The type of each data unit, where the data unit type includes subtitle, picture, file download, ESG or IP multicast.

(4) check code.

The length of each data unit 131 is variable, and there is no filling data. Compared with the TS encapsulation method, the utilization rate of data transmission is improved. The check code is to prevent bit errors and improve reliability.

The data unit 131 encapsulates specific content, which can include subtitles, pictures, files, electronic program guides, and IP multicast, and can realize various services in a variety of ways.

The present invention will be further described below by comparing a specific example with the prior art: In this example, a service channel has a rate of 256Kbit/s.

The total length of this channel data is 32K bytes, of which: subframe header 10 is 37 bytes long; video segment total length is 26.8K bytes; audio segment total length is 4.1K bytes; data segment header length is 21 bytes, There are 8 data units, and the total length of the data unit is 1K bytes. For parts less than 32K bytes, all 0s can be filled.

Such a TV channel can provide video data at a rate of 212Kbit/s, audio data at a rate of 32Kbit/s, and data at a rate of 8Kbit/s, which can meet the transmission of video data with QVGA resolution and 25 frames of H264 or AVS-M . While providing users with quite satisfactory quality mobile broadcast TV programs, it can also provide users with subtitles and pictures, which are displayed on the screen by the terminal.

The prior art adopts TS encapsulation. If 8 data units are encapsulated in TS packets for transmission, 10 TS packets are needed, 1504 bytes of bandwidth are required, and the utilization rate is less than 80%. The method of this patent improves the utilization rate by 20% compared with the TS method.

Claims (4)

1. A data transmission method of a mobile multimedia broadcasting system, comprising the steps of: (1) the service channel data is divided into a plurality of data units, and the data units are encapsulated in the data segment, and the length of each data unit and the type of the data unit are recorded in the data segment header; (2) Encapsulate the data segment and other data to be transmitted in a service channel for transmission; (3) After receiving the data segment, the terminal takes out each data unit according to the length of each data unit in the data segment header, and performs data reception or playback. 2. The data transmission method of the mobile multimedia broadcasting system according to claim 1, wherein the data segment header further includes a check code. 3. The data transmission method of the mobile multimedia broadcasting system according to claim 1, wherein the data unit type includes ESG, subtitle, file download or IP multicast. 4. The data transmission method of the mobile multimedia broadcasting system according to claim 1, wherein the service channel data includes one or more of subtitles, files, IP multicast, and ESG.

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