CN101193290A - A real time conversion system from MPEG-4 transmission code stream to Internet stream media alliance stream - Google Patents
A real time conversion system from MPEG-4 transmission code stream to Internet stream media alliance stream Download PDFInfo
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- CN101193290A CN101193290A CN 200610145626 CN200610145626A CN101193290A CN 101193290 A CN101193290 A CN 101193290A CN 200610145626 CN200610145626 CN 200610145626 CN 200610145626 A CN200610145626 A CN 200610145626A CN 101193290 A CN101193290 A CN 101193290A
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Abstract
The invention relates to a system for real-time transmitting transport stream TS in MPEG-4 to internet stream media alliance (ISMA) stream, which includes an encoder, a code converter, an IP network and a terminal. The code converter includes a configuration module, a receiving module, a de-multiplexing module, an encapsulating module and a transmitting module. The configuration module configures relevant parameters for the code converter, including encoding type of video and audio, program number of TS stream, a parameter of a session description protocol (SDP) of ISMA live broadcast stream. The TS stream from the encoder is received by the receiving module. According to configuration information, the de-multiplexing module de-multiplexes the TS stream, and according to program reference clock PCR value of the TS stream, corresponding frame reference time is generated by the de-multiplexing module. The obtained video and audio data after de-multiplexing is encapsulated as a real time transmission protocol (RTP) package by the encapsulating module according to the configuration information and frame reference time. The encapsulated RTP package is transmitted to the terminal according to the parameter of the SDP through the IP network by the transmitting module.
Description
Technical field
The invention belongs to field of multimedia communication, the transmission code stream (TS) that relates in particular to a kind of MPEG-4 flows to the real time conversion method of internet stream media alliance (ISMA) stream.
Background technology
Providing the real-time television video traffic by IP (Internet protocol) network is a kind of trend, and the rise of IPTV (Web TV) is exactly a kind of embodiment of this trend.IPTV transmits on broadband internet, adopts set-top box to add television set and shows and mutual a kind of new video traffic.
In the IPTV system, at present there is the transmission specification of two kinds of video flowings in industry, promptly in the Internet the widely used ISMA standard that proposes by internet stream media alliance (ISMA) and in CHINA RFTCOM Co Ltd the widely used TS standard that proposes by Motion Picture Experts Group (MPEG).The TS standard adopts TS to seal the dress form audio stream and the unified group of video flowing is wrapped and be multiplexed into a transport stream, and the ISMA agreement is then video flowing and separately transmission of audio stream, so these two kinds of standards are incompatible.
Because the ISMA agreement is to propose at Internet characteristics, can adapt to network characteristicses such as packet loss on the IP network, time-delay, shake preferably, add the professional operation experience of the existing internet stream media of telecom operators, therefore, telecom operators tend to adopt the ISMA transmission specification usually in the IPTV system, but television content is grasped in the broadcasting and TV system, adopts the TS transformat usually.In order to solve the format conversion problem, this paper has proposed to convert the code-transferring method of ISMA stream in real time to from TS stream, and has solved problems such as the time stamp generation in the transcoding process, Group Package Policy and transcoding time-delay control emphatically.
Summary of the invention
The video that the technical problem to be solved in the present invention provides a kind of traditional TS form flows to the real time conversion system of ISMA transport stream, for the IPTV system of telecom operators provides the solution of introducing real-time video from the broadcasting and TV system.
The transmission code stream TS of a kind of MPEG-4 flows to the RTTS of the ISMA of internet stream media alliance stream, comprise encoder, transcoder, IP network and terminal, described transcoder comprises configuration module, receiver module, demultiplexing module, package module and sending module, wherein:
Described configuration module is a transcoder configuration relevant parameter, comprise look, the audio coding type, TS flows program number, ISMA live TV stream Session Description Protocol SDP parameter, comprise the transmission connection type in the SDP parameter, i.e. transmission control protocol TCP or User Datagram Protoco (UDP) UDP and corresponding ports number;
Described receiver module receives the TS stream from encoder;
Described demultiplexing module is pressed configuration information demultiplexing TS stream, generates the corresponding frame reference time according to TS stream Program Clock Reference PCR value;
Described package module is encapsulated as the realtime transmission protocol RTP bag according to configuration information and the frame reference time TS stream after with demultiplexing;
Described sending module is sent to terminal according to the SDP parameter by IP network with the RTP bag of encapsulation.
The parameter of described configuration module configuration also comprises program receiving source NIC address; Send the program NIC address; Program source multicast network IP address, but non-multicast source value 0.0.0.0 then, and program source port numbers.
Described configuration module is with the form configuration parameter of configuration file, and each configuration file can dispose a plurality of programs.
During described package module encapsulate video RTP bag, each RTP bag comprises a video packets elementary stream PES at the most, and promptly each video PES load head is all in the starting point of RTP pay(useful) load Payload.
When described package module encapsulation audio frequency RTP wrapped, each RTP comprised one or more audio frequency PES, and a PES only belongs to a RTP bag.
The maximum length of the pay(useful) load Payload of the RTP bag of described package module encapsulation is no more than 1436 bytes.
Described sending module is not reserved buffer memory for ordering when sending the RTP bag.
Described sending module is that the buffer memory that the set of Marker sign is reserved in the RTP bag is no more than 1 UDP bag or TCP bag when sending the RTP bag.
Described sending module receives and adopts when sending data asynchronous mechanism, is unit to the lock control that adds of shared drive with UDP bag or TCP bag.
Described sending module sends after receiving the RTP bag of generation immediately.
The TS that adopts this paper invention to provide flows to the real time conversion system of ISMA stream, solved in the problem that the TS that inserts MPEG-4 looks audio content well, thereby provide solution for the IPTV system introduces traditional broadcasting and TV content source based on the IPTV system of ISMA transmission specification.
Description of drawings
Fig. 1 is that TS of the present invention flows to ISMA stream real time conversion system block diagram;
Fig. 2 is the real time conversion method flow chart that a kind of TS of the present invention flows to ISMA stream;
Fig. 3 is that TS seals dress form schematic diagram;
Fig. 4 is that the RTP of MPEG-4 video flowing seals dress form schematic diagram;
Fig. 5 is that the RTP of MPEG-4 audio stream seals dress form schematic diagram.
Embodiment
The present invention of being shown in Figure 1 comprises encoder, transcoder by the real time conversion system block diagram that TS flow to ISMA stream, IP network and terminal, wherein transcoder receives the TS stream from encoder, and this code stream is carried out being encapsulated as the RTP bag behind the demultiplexing, is sent to terminal by IP network again.Transcoder comprises configuration module, receiver module, demultiplexing module, package module and sending module, wherein:
Described configuration module is a transcoder configuration relevant parameter, comprise look, the audio coding type, TS flows program number, ISMA live TV stream Session Description Protocol SDP parameter, comprise the transmission connection type in the SDP parameter, i.e. transmission control protocol TCP or User Datagram Protoco (UDP) UDP and corresponding ports number;
Described receiver module receives the TS stream from encoder;
Described demultiplexing module is pressed configuration information demultiplexing TS stream, generates the corresponding frame reference time according to TS stream Program Clock Reference PCR value;
The video/audio that described package module obtained after with demultiplexing according to configuration information and frame reference time is encapsulated as the realtime transmission protocol RTP bag;
Described sending module is sent to terminal according to the SDP parameter by IP network with the RTP bag of encapsulation.
The function of each module further describes below.
The TS of a kind of MPEG-4 of the present invention of being shown in Figure 2 flows to the real time conversion method flow chart of ISMA stream, may further comprise the steps:
Before starting transcoder, earlier transcoder is carried out necessary configuration by configuration module, comprise look, the audio coding type, TS flows program number, ISMA live TV stream SDP (Session Description Protocol) etc. are configured in the configuration file mode, and a configuration file can be configured simultaneously to a plurality of programs.The configuration item of each program comprises:
1) program number: if TS stream is MPTS (Polymera TS code stream), the then program number of corresponding program (program_number); If TS stream is SPTS (multichannel single-unit order TS), then value is 0;
2) program receiving source NIC address;
3) send the program NIC address;
4) program source multicast ip address, but non-multicast source value 0.0.0.0 then;
5) program source port numbers;
6) program SDP (Session Description Protocol) comprises sending IP address, port numbers, sends connection type (TCP/UDP, transmission control protocol/User Datagram Protoco (UDP)), load type, and the clock frequency of medium type and time stamp defaults to 90kHz;
7) video, audio coding type.
Transcoder receives the TS over UDP stream (with the TS stream of udp protocol carrying) from encoder.The TS pack arrangement as shown in Figure 3, TS bag is made up of packet header, self adaptation district and bag data 3 parts.Each packet length is 188 fixing bytes, and packet header is 4 bytes, and self adaptation district and bag data are 184 bytes.184 bytes are the useful information space, are used to transmit the video/audio data flow of having encoded.Packet header is preferential by sync byte, transmission error code designator, PU Payload Unit start indicator, transmission, bag identification (PID-Packet Identification), transmission scrambling control, the control of self adaptation district and 8 parts of continuous counter are formed.
Transcoder is pressed configuration information demultiplexing TS stream, and (the grouping elementary stream PES with TS is a unit) tells video and audio code stream frame by frame, and is generated the reference time of corresponding frame by Program Clock Reference value (PCR); Transcoder obtains corresponding video-voice frequency flow PES after TS is flowed demultiplexing, gets the time stamp of the PCR value of PES head correspondence as this frame, and the relevant regulations of the concrete conversion method establishing criteria agreement ISO13818-1 of PCR value and time stamp is carried out.
Transcoder is further handled audio packet elementary stream (PES) data of looking that demultiplexing obtains, and according to configuration information and frame reference time, generates the RTP bag according to RFC3016 agreement (the RTP load format agreement that is used for the MPEG-4 audiovisual streams).The video of MPEG-4 and audio frequency RTP packet format are distinguished as shown in Figure 4 and Figure 5, and packet header generally only comprises 12 bytes of beginning, and the CSRC identification field does not generally need.Field V presentation protocol version, field P represents whether comprise padding data, X field represents whether protocols having is expanded, and the CC field is represented the CSRC conventional number, and whether the M field identification is last RTP bag of VOP, the PT field is represented load type, Sequence Number is a sequence number, initial value at random, Timestamp is the time stamp field, indicate the sampling instant of the VOP that is comprised in this RTP bag, SSRC is a random number of sign synchronisation source.Because the TS of input bag is not corresponding one by one with the RTP bag of output, the RTP Group Package Policy is as follows:
1) video RTP bag comprises a PES at the most, and promptly each video PES load head is all in the starting point of RTP pay(useful) load (Payload);
2) audio frequency RTP bag can comprise a plurality of PES, but a PES can not stride a plurality of RTP bags, and promptly each audio frequency RTP pay(useful) load (Payload) starting point is a PES load head;
3) Voice ﹠ Video RTP is surrounded by the maximum length of imitating load (Payload) and is no more than 1436 bytes.
The audio frequency RTP bag of looking that transcoder will generate is sent to network separately by the udp port that disposes.In order to ensure live real-time, the time delay of transcoding should be as far as possible little.Strategy that adopts and mechanism are as follows:
1) because encoder generally is directly to link to each other with transcoder, therefore do not consider packet loss and out of order situation, promptly needn't reserve buffer memory for ordering;
2) Marker must be identified set owing to look last RTP bag of audio frame, if the PES length value of TS stream is 0 (the PES length of TS stream video packets mostly is 0 greatly), having only could the judgment frame border by PES flag bit.Thereby need a certain amount of data of buffer memory with Decision boundaries.From next effectively (containing the ES data) TS bag can determine whether the current TS bag is frame boundaries, institute thinks that buffer memory that Marker set is reserved can be 1 UDP at most and wraps.Wrap generation RTP according to a TS and wrap the back temporary cache, wait to receive to determine the Marker that whether RTP is wrapped to identify set again after next TS wraps, and then send.
3) for avoiding factor influence packet and receive according to handling and sending, receive with handling and send the general asynchronous mechanism that adopts, should be unit with the UDP bag to the lock control that adds of shared drive, promptly wrapping with whole UDP is that unit adds lock control.The buffering area that takies such as this bag is locked by receiving process when receiving, and avoids treatment progress that it is made amendment.Each bag all has a lock, rather than lock of whole buffering area (memory block), is convenient to two process concurrent workings like this, promptly can not produce too much processing time-delay.To reject the buffer memory that produces because of asynchronous mechanism;
4) sending module sends to destination address after receiving the RTP bag of generation immediately, does not make flow control and buffer memory.
Above-mentioned transmission also can be adopting the TCP mode, when adopting the TCP mode, and the same UDP of send mode.
Claims (10)
1. the transmission code stream TS of a MPEG-4 flows to the RTTS of the ISMA of internet stream media alliance stream, comprise encoder, transcoder, IP network and terminal, it is characterized in that: described transcoder comprises configuration module, receiver module, demultiplexing module, package module and sending module, wherein:
Described configuration module is a transcoder configuration relevant parameter, comprise look, the audio coding type, TS flows program number, ISMA live TV stream Session Description Protocol SDP parameter, comprise the transmission connection type in the SDP parameter, i.e. transmission control protocol TCP or User Datagram Protoco (UDP) UDP and corresponding ports number;
Described receiver module receives the TS stream from encoder;
Described demultiplexing module is pressed configuration information demultiplexing TS stream, generates the corresponding frame reference time according to TS stream Program Clock Reference PCR value;
The video/audio that described package module obtained after with demultiplexing according to configuration information and frame reference time is encapsulated as the realtime transmission protocol RTP bag;
Described sending module is sent to terminal according to the SDP parameter by IP network with the RTP bag of encapsulation.
2. the system as claimed in claim 1 is characterized in that: the parameter of described configuration module configuration also comprises program receiving source NIC address; Send the program NIC address; Program source multicast network IP address, but non-multicast source value 0.0.0.0 then, and program source port numbers.
3. system as claimed in claim 1 or 2 is characterized in that: described configuration module is with the form configuration parameter of configuration file, and each configuration file can dispose a plurality of programs.
4. the system as claimed in claim 1 is characterized in that: during described package module encapsulate video RTP bag, each RTP bag comprises a video packets elementary stream PES at the most, and promptly each video PES load head is all in the starting point of RTP pay(useful) load Payload.
5. the system as claimed in claim 1 is characterized in that: during described package module encapsulation audio frequency RTP bag, each RTP comprises one or more audio frequency PES, and a PES only belongs to a RTP and wraps.
6. as claim 4 or 5 described systems, it is characterized in that: the maximum length of the pay(useful) load Payload of the RTP bag of described package module encapsulation is no more than 1436 bytes.
7. the system as claimed in claim 1 is characterized in that: when described sending module wraps at transmission RTP, do not reserve buffer memory for ordering.
8. the system as claimed in claim 1 is characterized in that: described sending module is that the buffer memory that the set of Marker sign is reserved in the RTP bag is no more than 1 UDP bag or TCP bag when sending the RTP bag.
9. the system as claimed in claim 1 is characterized in that: described sending module receives and adopts when sending data asynchronous mechanism, is unit to the lock control that adds of shared drive with UDP bag or TCP bag.
10. the system as claimed in claim 1 is characterized in that: described sending module sends after receiving the RTP bag of generation immediately.
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| Application Number | Priority Date | Filing Date | Title |
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| CN 200610145626 CN101193290A (en) | 2006-11-22 | 2006-11-22 | A real time conversion system from MPEG-4 transmission code stream to Internet stream media alliance stream |
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| CN 200610145626 CN101193290A (en) | 2006-11-22 | 2006-11-22 | A real time conversion system from MPEG-4 transmission code stream to Internet stream media alliance stream |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101945265A (en) * | 2010-08-19 | 2011-01-12 | 北京市博汇科技有限公司 | Bandwidth occupancy rate based multi-program constant code rate TS flow multiplexing algorithm |
| CN102647584A (en) * | 2012-04-26 | 2012-08-22 | 广州盈可视电子科技有限公司 | Video file generation method and system |
| CN105847265A (en) * | 2016-03-31 | 2016-08-10 | 乐视控股（北京）有限公司 | Video living streaming transcoding method and device |
| CN108156464A (en) * | 2017-12-19 | 2018-06-12 | 青岛海信网络科技股份有限公司 | A kind of method and device of multipath concurrence transcoding |
| CN110198474A (en) * | 2018-02-27 | 2019-09-03 | 中兴通讯股份有限公司 | A kind of code flow processing method and device |
| CN114189563A (en) * | 2021-11-19 | 2022-03-15 | 深圳市鼎盛威电子有限公司 | Intelligent multimedia protocol conversion device for smart hotel |
-
2006
- 2006-11-22 CN CN 200610145626 patent/CN101193290A/en not_active Withdrawn
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101945265A (en) * | 2010-08-19 | 2011-01-12 | 北京市博汇科技有限公司 | Bandwidth occupancy rate based multi-program constant code rate TS flow multiplexing algorithm |
| CN102647584A (en) * | 2012-04-26 | 2012-08-22 | 广州盈可视电子科技有限公司 | Video file generation method and system |
| CN105847265A (en) * | 2016-03-31 | 2016-08-10 | 乐视控股（北京）有限公司 | Video living streaming transcoding method and device |
| CN108156464A (en) * | 2017-12-19 | 2018-06-12 | 青岛海信网络科技股份有限公司 | A kind of method and device of multipath concurrence transcoding |
| CN110198474A (en) * | 2018-02-27 | 2019-09-03 | 中兴通讯股份有限公司 | A kind of code flow processing method and device |
| CN110198474B (en) * | 2018-02-27 | 2022-03-15 | 中兴通讯股份有限公司 | Code stream processing method and device |
| US11523174B2 (en) | 2018-02-27 | 2022-12-06 | Zte Corporation | Bitstream processing method and device |
| CN114189563A (en) * | 2021-11-19 | 2022-03-15 | 深圳市鼎盛威电子有限公司 | Intelligent multimedia protocol conversion device for smart hotel |
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