CN100421449C - Control method for clock synhrronous preservation in network degital TV system - Google Patents
Control method for clock synhrronous preservation in network degital TV system Download PDFInfo
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- CN100421449C CN100421449C CNB2004100536551A CN200410053655A CN100421449C CN 100421449 C CN100421449 C CN 100421449C CN B2004100536551 A CNB2004100536551 A CN B2004100536551A CN 200410053655 A CN200410053655 A CN 200410053655A CN 100421449 C CN100421449 C CN 100421449C
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Abstract
The present invention relates to a control method for clock synchronous preservation in a network digital TV system. In the developing process of introducing a digital TV program into an IP network, time information is maintained in a demultiplexing unit and a remultiplexing unit. After the transmission of the network, the original time information is recovered on the receiving end according to the information in transmit flow, and the effective data of the program can be transmitted in the network at a variable code rate. The system clock synchronization on the encoding end and the decoding end can be achieved by a time information mould at a constant code rate. By the present invention, the demultiplexing processing and the remultiplexing processing are simple without need of correcting time information, and the generated transmit flow with a single program system with time synchronous information is more suitable for being transmitted in the IP network. The recovered time synchronous information with the same transmit flow of the original multiple program system can be used as a decoder clock of a synchronizing system to eliminate various phenomena caused by non-synchronous encoding and decoding.
Description
Technical field
What the present invention relates to is a kind of control method that is used for the network digital TV transmission technique field, the control method that particularly a kind of network digital TV system clock keeps synchronously.
Technical background
Current, general digital tv encoder technology is to adopt MPEG-2 video encoding standard, and it is by ISO/IEC
13818 file descriptions, this document have also defined the system layer structure of coding output code flow, have also defined the time model of a maintenance codec clock synchronization simultaneously.Simultaneously standard has also defined a Program Clock Reference (PCR) value and has been used for the system clock of this program stream of mark in code stream, but be defined in the processing of carrying out code stream in the standard, as demultiplexing, will be during multiplexing again and code check change process according to the strict temporal information parameter PCR value of revising this code stream of standard code.Development along with Digital Television and broadband IP network, in IP network, carry out carrying out of digital television business and become important application, experimental results show that simultaneously, the transmitting digital TV program should adopt the form of the single-unit order system transport stream of only transmitting the program valid data in IP network, such form tends to cause showing as in system layer the single-unit order system transport stream of variable bit rate speed, such system transport stream will be than more effective by increasing the empty system transport stream of keeping constant code rate speed (CBR) of wrapping, not only improve channel utilization, and agreed with the service mode of IP network " Best-effort ".This means the demultiplexing that must carry out the Polymera system transport stream when in network, introducing digital television program, generation single-unit order system transport stream is carried out the transmission in the network, will guarantee that simultaneously these time models of handling the clock synchronization that needs to transmit later more effective definition that maintains the standard simultaneously of process are still effective.And traditional Polymera demodulation multiplexer is in order to keep the effective of these temporal informations, when demultiplexing, change because of the position of PCR in code stream, so not only will carry out strict (PCR) temporal information correction, and will be by increasing empty bag to keep the form output of constant code rate speed (CBR), be not suitable for effectively transmission in the IP network of sharing, also increased the complexity that code stream is handled simultaneously.
In the ISO/IEC13818 of Moving Picture Experts Group-2 file, the description that appendix D " ITU-T is Timing Model and Application Implications H.222.0|ISO/IEC13818-1Systems " is detailed the realization and the meaning of this system clock synchronistic model, point out simultaneously when the processing of carrying out code stream and transmission, can introduce PCR shake (JITTER), these shakes are had plenty of owing to carry out that the processing of code stream causes, have plenty of owing to cause during Network Transmission.Appendix D suggestion will be carried out strict PCR and revise the shake that suggestion uses Smoothing Buffer smooth network to cause after the transmission of carrying out code stream when carrying out the processing of code stream.In the ISO/IEC13818 of Moving Picture Experts Group-2 file, appendix K " Interfacing Jitter-InducingNetworks to MPEG-2 Decoders " suggestion uses FIFO and PLL to eliminate the shake of CBR in Network Transmission, advises that also the timestamp of other a kind of method use network layer assists to eliminate the shake that Network Transmission causes.Shake the thought of correction respectively but said method all is based on handling shake and transmission, so single ending handled complexity, can't remove all shakes, and do not have abundant service mode in conjunction with Network Transmission.
Summary of the invention
The objective of the invention is to overcome the deficiencies in the prior art and defective, the control method that provides a kind of network digital TV system clock to keep synchronously, can realize that digital television program only transmits the valid data of this program in network, revert to constant code rate speed at receiving terminal, and with correct PCR value synchro system clock, implementation structure is simple, and has good divergence, is applicable to carrying out in the digital television business introducing broadband IP network.
The present invention is achieved by the following technical solutions, the present invention introduces broadband IP network to digital television program and carries out in the process, demultiplexing and again Multiplexing Unit carry out the maintenance of temporal information, through after the transmission of network, recover original temporal information at receiving terminal according to the information in the transport stream, and can transmit the valid data of this program with variable bit rate speed in network, the system clock that reaches coding side and decoding end with the temporal information model of constant code rate speed is synchronous.
Described " demultiplexing and multiplexing again ", be when when being input as the digital television program system transport stream of conventional digital TV radio network, demultiplexing and again the multiplexing process unit according to the information of input system transport stream, regenerate the single-unit order system transport stream that has time synchronization information, this single-unit order system transport stream only comprises the effective video/audio of program and transmits in broadband IP network, such system transport stream will be than more effective by increasing the empty system transport stream of keeping constant code rate speed of wrapping, not only improve channel utilization, and the service mode of having agreed with IP network " Best-effort ", at receiving terminal, recovery time, information process unit reverted to the code stream of constant code rate speed again according to the single-unit order system transmissions that has time synchronization information that receives, the time synchronization information PCR value of this constant code rate speed code stream makes the system clock of this program stream decoder synchronous with to enter the input demultiplexing the same with the position before the multiplexing process unit again.
Described " system clock is synchronous ", comprise front end demultiplexing and multiplexing process unit, Network Transmission processing unit, receiving terminal information process unit recovery time again, demultiplexing and again the multiplexing process unit refer to the digital television system transport stream that will carry out effective Network Transmission is handled, to generate the single-unit order digital television system transport stream that correspondence comprises; The Network Transmission processing unit refers to for effective transmitting digital TV system transport stream, the protocol processes of carrying out when carrying out Network Transmission; Receiving terminal information process unit recovery time refers in terminal, receive the network data of digital television system transport stream of transmission after, for the correct processing that recovers the system time information of this system transport stream and carry out.
When being input as the digital television program system transport stream of conventional digital TV radio network, reverting to constant code rate speed at receiving terminal, and, comprise being achieved as follows step with the PCR value synchro system clock of orthochronous information:
1. the Digital Television multi-channel program system transport stream of input is carried out demultiplexing and multiplexing process again, the PCR value that does not need to carry out temporal information in the demultiplexing processing procedure is revised, and only needs to keep the temporal information and the relative position of some information of insertion with record program transmission bag of original program; Equally the PCR value that does not need to carry out temporal information in multiplexing process process is again revised, and generates not comprise the empty single-unit order transmission code stream that wraps;
2. the single-unit order transmission code stream that does not comprise empty bag that generates in network with the variable bit rate speed rates;
3. at receiving terminal, the information that recovery time, information process unit comprised according to this single-unit order system transport stream reverts to the code stream of constant code rate speed again, and the time synchronization information PCR value of this constant code rate speed code stream is with to enter the input demultiplexing the same with the position before the multiplexing process unit again.
Network digital TV system clock of the present invention keeps implementation synchronously when carrying out the digital TV network business, with a kind of more easy mode carry out demultiplexing and again multiplexing process generate the corresponding single-unit order system transport stream that will transmit that comprises, the Network Transmission processing unit is handled with a kind of more effective and easy procotol, can be implemented in the valid data that in network, transmit this program in the network with variable bit rate speed, play with the decoding of constant code rate speed at receiving terminal, in terminal, receiving terminal information process unit recovery time is handled accordingly according to the network data information received, can recover and enters the demultiplexing and the same precise time information of transport stream of multiplexing process unit more originally.It is simple in structure that calculation process of the present invention realizes, and have good divergence.No matter be with respect to carrying out code stream demultiplexing that the network digital TV business carries out multiplexing process again, still with respect to only transmit the effective code stream bit rate in network, can recover accurate system time information at receiving terminal, method of the present invention all has applicability.
Description of drawings
Fig. 1 introduces digital television program at broadband IP network from the digital television broadcasting net and carries out the system block diagram of network digital TV business
Illustrate: the transmission parcel (TP) of Digital Television single-unit order N is labeled as TSN, N=1,2 Empty transmission parcel (TP) marker bit NULL; The transmission parcel (TP) that comprises the system time information PCR value of Digital Television single-unit order N is labeled as PCRN, N=1,2 ...Among Fig. 1, comprise demultiplexing and multiplexing process unit again, flow through demultiplexing and again after the multiplexing process of the digital television program system transmissions of input generates the single-unit order system transport stream that has time synchronization information.Single-unit order system transmissions is flowed through after the Network Transmission processing unit processes, transmits in broadband IP network with the form of IP stream.Receive at receiving terminal after the IP stream of transmission, at first go network jitter to handle, then the single-unit order system transport stream that has time synchronization information that receives is handled, recover and the original the same time synchronization information of Polymera system transport stream.
Fig. 2 demultiplexing and multiplexing process block diagram again
Among Fig. 2, signal generates the single-unit order system transport stream that has time synchronization information.
Fig. 3 information process unit recovery time block diagram
Among Fig. 3, signal recovers and the original the same time synchronization information figure of Polymera system transport stream.
Fig. 4 is according to the application scenarios and the concrete system block diagram of one embodiment of the present of invention.
Fig. 4 is the application scenarios and the concrete system block diagram of one embodiment of the invention, is applied in broadband IP network, introduces digital television program from the digital television broadcasting net and carries out the network digital TV business.
Embodiment
Below in conjunction with accompanying drawing and specific embodiment technical scheme of the present invention is further described.
Because the digital television business transmission mode of digital television broadcasting net is the forms of broadcasting, and the broadband IP network service transmission mode is two-way, share, the form of best effort, thereby in broadband IP network with the transmission operating mode of the more suitable IP network of load mode of single-unit order system transport stream.Thereby need carry out information extraction and parsing to the digital television program that enters broadband IP network, and the demultiplexing of digital television program and multiplexing again, the single-unit order system transport stream that is fit to the IP network transmission generated.
As Fig. 1, shown in 4, in the process of specific implementation digital television business IP network transmission, digital television program can be from terrestrial broadcasting, satellite transmits, the radio network that digital cable etc. are traditional, the Polymera system transport stream that has orthochronous information that receives is at first carried out demultiplexing and multiplexing process again, in this processing process, do not need the accurate regulation of image scale to carry out complicated strict temporal information correction like that, but fully take into account network processes, transmit and receive the coordinated of recovery processing,, simply realize network TV business with the mode that meets network transmission efficiency jointly with a kind of more efficient.
The Polymera system transport stream that receives is carried out demultiplexing and multiplexing process again among Fig. 2, generation has the single-unit order system transport stream of time synchronization information, bag identification (PID) to the digital television program system transport stream of input is analyzed, if Dui Ying transmission parcel (TP) is the just reservation that constitutes the single-unit order system transport stream of required transmission as shown in the figure, if corresponding transmission parcel (TP) is the sync bit mark (Tag) that empty bag just replaces with a byte, if corresponding transmission parcel (TP) is the sync bit mark (Tag) that also replaces with a byte that constitutes the single-unit order system transport stream of other transmission.The single-unit order system transport stream that has time synchronization information of Sheng Chenging only comprises valid data and a spot of time synchronization information that constitutes this program like this, can not waste the IP network transmission bandwidth.
The Network Transmission processing unit carries out the needed protocol encapsulation of Network Transmission to the single-unit order system transport stream that has time synchronization information to be handled, for example can carry out just being encapsulated in the Frame after Fig. 2 handles and carry out Network Transmission, also can carry out protocol encapsulation and handle transmission with fixing frame length data to 7 transmission parcels.
At receiving terminal, the suggestion that can use in the Moving Picture Experts Group-2 goes network jitter to handle.The data that receive are carried out processing shown in Figure 3, Fig. 3 is that the present invention carries out information processing recovery time to the single-unit order system transmissions that has time synchronization information that receives, check the data of receiving as shown in the figure, if sync bit mark (Tag) then replaces with an empty bag, the data flow of then recover with entered demultiplexing originally and compare with the data flow of Multiplexing Unit again and only comprise the single-unit destination data, this single-unit order packet, just can not recover and is used as the synchro system decoder should single-unit information object time (PCR value) not needing to do any processing like this with the same in the position of original data flow in the position of data flow.From corresponding diagram 3 and Fig. 2 correspondence as can be seen the position code stream of temporal information bag be living, show code stream handle and network transmission process in introduce the shake of any time information.In the IP traffic of transmission, valid data and a spot of temporal information sync mark of a digital television program have only been comprised, show the constant bandwidth that in the transmission of Digital Television IP network, has changed the transmission of conventional digital TV radio network, the pattern of fixed delay is with a kind of mode transfer of more bandwidth efficient.
Claims (3)
1. the control method that keeps synchronously of a network digital TV system clock, it is characterized in that, digital television program is introduced broadband IP network to be carried out in the process, demultiplexing and again Multiplexing Unit carry out the maintenance of temporal information, through after the transmission of network, recover original temporal information at receiving terminal according to the information in the transport stream, and can in network, transmit the valid data of this program with variable bit rate speed, the system clock that reaches coding side and decoding end with the temporal information model of constant code rate speed is synchronous, when when being input as the digital television program system transport stream of conventional digital TV radio network, demultiplexing and again the multiplexing process unit according to the information of input system transport stream, regenerate the single-unit order system transport stream that has time synchronization information, this single-unit order system transport stream only comprises the effective video/audio of program and transmits in broadband IP network, at receiving terminal, recovery time, information process unit reverted to the code stream of constant code rate speed again according to the single-unit order system transmissions that has time synchronization information that receives, the time synchronization information PCR value of this constant code rate speed code stream makes the system clock of this program stream decoder synchronous with to enter the input demultiplexing the same with the position before the multiplexing process unit again.
2. the control method that network digital TV system clock as claimed in claim 1 keeps synchronously, it is characterized in that, described " system clock is synchronous ", comprise front end demultiplexing and multiplexing process, Network Transmission processing, receiving terminal information processing recovery time again, demultiplexing and again multiplexing process refer to the digital television system transport stream that will carry out effective Network Transmission is handled, to generate the single-unit order digital television system transport stream that correspondence comprises; Network Transmission is handled and is referred to for effective transmitting digital TV system transport stream, the protocol processes of carrying out when carrying out Network Transmission; Receiving terminal information processing recovery time refers in terminal, receive the network data of digital television system transport stream of transmission after, for the correct processing that recovers the system time information of this system transport stream and carry out.
3. the control method that network digital TV system clock as claimed in claim 1 keeps synchronously, it is characterized in that, when being input as the digital television program system transport stream of conventional digital TV radio network, revert to constant code rate speed at receiving terminal, and, comprise being achieved as follows step with the PCR value synchro system clock of orthochronous information:
1. the Digital Television multi-channel program system transport stream of input is carried out demultiplexing and multiplexing process again, the PCR value that does not need to carry out temporal information in the demultiplexing processing procedure is revised, and only needs to keep the temporal information and the relative position of some information of insertion with the recorded program transmission package of original program; Equally the PCR value that does not need to carry out temporal information in multiplexing process process is again revised, and generates not comprise the empty single-unit order transmission code stream that wraps;
2. the single-unit order transmission code stream that does not comprise empty bag that generates in network with the variable bit rate speed rates;
3. at receiving terminal, the information that recovery time, information process unit comprised according to this single-unit order system transport stream reverts to the code stream of constant code rate speed again, and the time synchronization information PCR value of this constant code rate speed code stream is with to enter the input demultiplexing the same with the position before the multiplexing process unit again.
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| CNB2004100536551A CN100421449C (en) | 2004-08-12 | 2004-08-12 | Control method for clock synhrronous preservation in network degital TV system |
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| CN100421449C true CN100421449C (en) | 2008-09-24 |
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| US8908577B2 (en) | 2005-12-02 | 2014-12-09 | Qualcomm Incorporated | Solving IP buffering delays in mobile multimedia applications with translayer optimization |
| CN100563336C (en) * | 2008-01-03 | 2009-11-25 | 上海广电（集团）有限公司中央研究院 | A kind of constant code rate control method based on mobile TV |
| CN101540897B (en) * | 2008-03-21 | 2013-04-24 | 中国科学院声学研究所 | Interactive television program stream time stamp issuing method for cable TV network |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1287745A (en) * | 1998-11-04 | 2001-03-14 | 夏普公司 | Digital broadcast receiving system |
| CN1441601A (en) * | 2003-01-24 | 2003-09-10 | 浙江大学 | Signal transmission method in digital TV transmission |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1287745A (en) * | 1998-11-04 | 2001-03-14 | 夏普公司 | Digital broadcast receiving system |
| CN1441601A (en) * | 2003-01-24 | 2003-09-10 | 浙江大学 | Signal transmission method in digital TV transmission |
Non-Patent Citations (2)
| Title |
|---|
| MPEG-2数字视频广播传输流中节目参考时钟的处理. 金盛，张文军，余松煜.红外与激光工程，第29卷第5期. 2000 |
| MPEG-2数字视频广播传输流中节目参考时钟的处理. 金盛，张文军，余松煜.红外与激光工程，第29卷第5期. 2000 * |
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