CN101202918B - Method of terminal correcting clock - Google Patents
Method of terminal correcting clock Download PDFInfo
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- CN101202918B CN101202918B CN2006101611830A CN200610161183A CN101202918B CN 101202918 B CN101202918 B CN 101202918B CN 2006101611830 A CN2006101611830 A CN 2006101611830A CN 200610161183 A CN200610161183 A CN 200610161183A CN 101202918 B CN101202918 B CN 101202918B
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- local clock
- clock
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Abstract
A clock correcting method for terminals comprises the following steps: (1) the terminal receives the program data sent by a system side and sets a local clock as T0 when receiving the data for the first time and the terminal receives business data with fixed time length every time. (2) Whenever the terminal receives data, the terminal calculates according to the initial time T0, the times N of data receiving and fixed time interval T to obtain a current time X and corrects the local clock with the current time X.
Description
Technical field
The invention belongs to Mobile Multimedia Broadcasting or technical field of mobile TV, specially refer to a kind of method of clock synchronization of the real-time video audio stream of realizing Mobile Multimedia Broadcasting.
Background technology
Mobile Multimedia Broadcasting is a kind of Play Technique for Multimedia of rising in recent years.By hand-held terminal, under the situation of high-speed mobile, can watch TV.Terminal receives programme by wireless protocols, and can select the channel of oneself having the right to watch, thereby can receive the multi-medium data of selecting channel, is implemented in and sees TV on the portable terminal.
The aerial data of system emission are divided into different channels, and the data of each channel comprise three types of video, audio frequency and data again, require to guarantee energy synchronous playing between terminal and the system, be that clock is synchronous, also require terminal can guarantee the synchronous playing of video/audio, promptly labial is synchronous.Clock synchronization is basic functions in the multi-media broadcasting system.
In the multimedia broadcasting field, the method for existing assurance clock synchronization has 2 kinds.A kind of is TS (transport stream) agreement, constantly sends Program Clock Reference (PCR) bag by system side, allows ceaselessly position of terminal, is synchronous with the clock that guarantees terminal and the clock of system equipment.Another kind method is NTP (Network Time Protocol) NTP, and at set intervals, for example 1 hour, server and client were done once mutual, proofreaded the time.
First method is adapted at using in the circuit network, also being fit to unidirectional broadcast network uses, clock can guarantee very accurate, but the TS mode will send 3 to 10 times each second at least comes position, each is surrounded by 188 byte-sized, advantage is the precision height, and shortcoming is to have wasted bandwidth resources, the complexity height of TS realization simultaneously; Second method is adapted at using in the IP network, and is very little to the expense of the network bandwidth, is two-way but require network, can only use in interactive network, is not suitable for using in the radio network.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of method of terminal correcting clock, only needs less overhead, just can realize the clock synchronization between terminal and the system coding equipment.
In order to address the above problem, the present invention proposes a kind of method of terminal correcting clock, may further comprise the steps:
(2) program data sent of terminal receiving system side is put T with local clock when receiving data the 1st time
0, receive the business datum of set time length at every turn;
When (3) terminal is received data at every turn, according to initial time T
0, the times N and the Fixed Time Interval T that receive data calculate current time X, and with described current time X correcting local clock.
Further, said method can also have following characteristics: in the step (3), the time that the terminal record calculates at every turn, whenever receive 1 secondary data, all on preceding local clock basis of once calculating, add Fixed Time Interval T, promptly obtain being used to proofread and correct the synchronised clock of terminal this locality in the mode that adds up.
Further, said method can also have following characteristics: in the step (3), and current time X=T * (N-1)+T
0
Further, said method can also have following characteristics: in the step (3), and local clock initial value T
0Reproduction time stamp for first picture frame that is played or speech frame.
Further, said method can also have following characteristics, and step (2) also comprises before: (1) terminal is selected programme content according to electronic program list.
Further, said method can also have following characteristics: step (3) also comprises afterwards: (4) decoding terminals video data, voice data, and stab according to their reproduction time, the contrast local clock is regularly play.
Further, said method can also have following characteristics: in the time of terminal plays video data and voice data, turn back to step (2), continue to receive data.
Further, said method can also have following characteristics: if when terminal initial receives data, be T with the initial clock setting in this locality
0, then stab when identical at the local clock and the reproduction time of decoded video data, voice data, carry out the timing synchronous playing.
Further, said method can also have following characteristics: if clear 0 to local clock when terminal initial receives data, then local clock is identical with the reproduction time stamp of decoded video data, voice data, carries out the timing synchronous playing.
Prior art adopts the TS mode to realize, the complexity height that TS realizes need send several clock check and correction bags each second, and each is surrounded by 188 byte longs, has brought the expense of radio spectrum resources.Compared with prior art, the present invention can send a clock synchronization with reference to guaranteeing clock synchronization in each second, and overhead is very little.The present invention is adapted at using in the radio network, the clock synchronization between energy realization system and the terminal.
Description of drawings
Fig. 1 is the schematic diagram of system clock synchronizing method among the embodiment.
Fig. 2 is the schematic diagram of system clock transmission method among the embodiment.
Fig. 3 is the schematic diagram of terminal check and correction local clock among the embodiment.
Embodiment
The present invention is a kind of method of Mobile Multimedia Broadcasting clock synchronization, for same service channel, in each Fixed Time Interval, send one time business datum, mobile network's the time interval is very accurate, do not have cumulative errors, terminal can be utilized this time interval correcting local clock, thereby can guarantee clock synchronization.
Be elaborated below in conjunction with 1 pair of the inventive method of accompanying drawing.Said method comprising the steps of:
In case because asynchronous between the encoder, the time has been grown, and just forms cumulative errors, cause buffering area to overflow, and regular check and correction can be eliminated cumulative errors.
As shown in Figure 2, radio broadcasting is to send 1 full frame structured data in a Fixed Time Interval, this Fixed Time Interval T can be 1 second, 0.5 second kind, or other times are at interval.
Among another embodiment, terminal also can write down the time that at every turn calculates, and whenever receives 1 secondary data, all adds Fixed Time Interval T on preceding local clock basis of once calculating, and promptly obtains being used to proofread and correct the synchronised clock of terminal this locality in the mode that adds up.
Receive business datum at every turn, utilize to calculate gained clock check and correction terminal local clock, can guarantee that the time interval of terminal plays frame of video, audio frame and the time interval of encoder equate fully, thus the realization clock synchronization.
Fig. 3 has illustrated the embodiment of end side check and correction local clock, may further comprise the steps:
Step 210, terminal is selected programme content according to electronic program list;
Step 220, terminal begin the program data that the receiving system side is sent, and during the 1st reception data local clock are put T
0, receive the business datum of set time length at every turn, suppose and can receive the business datum in a second 1 time;
When step 230, terminal are received data at every turn, according to initial time T
0, the times N and the Fixed Time Interval T that receive data calculate current time X, and with described current time X correcting local clock;
Terminal is calculated from receiving data for the 1st time to the N time time interval X, and the computational methods of this example employing are X=T * (N-1), proofread local clock according to described time interval X.
Terminal also can write down the time that at every turn calculates, and whenever receives 1 secondary data, all adds Fixed Time Interval T on preceding local clock basis of once calculating, and promptly obtains being used to proofread and correct the synchronised clock of terminal this locality in the mode that adds up.
Step 240, decode video data, voice data, and stab according to their reproduction time, the contrast local clock is regularly play, and turns back to step 220 simultaneously, continues to receive data.
If when terminal initial receives data, be T with the initial clock setting in this locality
0, then stab when identical at the local clock and the reproduction time of decoded video data, voice data, carry out the timing synchronous playing;
If clear 0 to local clock when terminal initial receives data, then local clock is identical with the reproduction time stamp of decoded video data, voice data, carries out the timing synchronous playing.
Like this, in the time interval of each image, encoded speech data, just the time interval of Bo Fanging, encode and the clock synchronization issue of playing thereby solved.
At an application example, service channel 1 has the speed of 256Kbit/s, encoder sends 1 secondary data each second, behind the starting up of terminal, receives wireless signal, take out the data in first second, the system-timing reference value is stabbed for the reproduction time of first picture frame that is played or speech frame, and every a second, terminal is received once new data, again proofread the terminal local clock one time, to guarantee the clock synchronization of terminal and encoder.
Claims (9)
1. the method for a terminal correcting clock, this terminal links to each other with system side by the mobile network, may further comprise the steps:
(2) program data sent of terminal receiving system side is put T with local clock when receiving data the 1st time
0, receive the program data of set time length at every turn;
When (3) terminal is received program data at every turn, according to initial time T
0, the program receiving data times N and Fixed Time Interval T calculate current time X, and with described current time X correcting local clock.
2. method according to claim 1 is characterized in that:
In the step (3), the time that the terminal record calculates at every turn, whenever receive the program data 1 time, all on preceding local clock basis of once calculating, add Fixed Time Interval T, promptly obtain being used to proofread and correct the synchronised clock of terminal this locality in the mode that adds up.
3. method according to claim 1 is characterized in that:
In the step (3), current time X=T * (N-1)+T
0
4. as method as described in claim 2 or 3, it is characterized in that:
In the step (3), local clock initial value T
0Reproduction time stamp for first picture frame that is played or speech frame.
5. method according to claim 1 is characterized in that step (2) also comprises before:
(1) terminal is selected programme content according to electronic program list.
6. method according to claim 1 is characterized in that step (3) also comprises afterwards:
(4) terminal receives decoded video data, voice data, and stabs according to their reproduction time, and the contrast local clock is regularly play.
7. as method as described in the claim 6, it is characterized in that:
In the time of terminal plays video data and voice data, turn back to step (2), continue the program receiving data.
8. as method as described in the claim 7, it is characterized in that:
If when terminal initial program receiving data, be T with the initial clock setting in this locality
0, then stab when identical at the local clock and the reproduction time of decoded video data, voice data, carry out the timing synchronous playing.
9. as method as described in the claim 7, it is characterized in that:
If clear 0 to local clock when terminal initial program receiving data, then local clock and the reproduction time of decoded video data, voice data stab identically, carry out the timing synchronous playing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2006101611830A CN101202918B (en) | 2006-12-11 | 2006-12-11 | Method of terminal correcting clock |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2006101611830A CN101202918B (en) | 2006-12-11 | 2006-12-11 | Method of terminal correcting clock |
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| Publication Number | Publication Date |
|---|---|
| CN101202918A CN101202918A (en) | 2008-06-18 |
| CN101202918B true CN101202918B (en) | 2010-04-14 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2006101611830A Expired - Fee Related CN101202918B (en) | 2006-12-11 | 2006-12-11 | Method of terminal correcting clock |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB201116521D0 (en) | 2011-09-23 | 2011-11-09 | Imagination Tech Ltd | Method and apparatus for time synchronisation in wireless networks |
| CN104038303B (en) * | 2014-06-09 | 2017-01-18 | 常青 | Remote aiding method and system |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1647552A (en) * | 2002-04-22 | 2005-07-27 | 诺基亚有限公司 | Media system, user terminal and method of providing content items relating to broadcast media stream |
| CN1812289A (en) * | 2005-01-26 | 2006-08-02 | 中兴通讯股份有限公司 | Apparatus for realizing network synchronization in personal cell phone based on IP |
| CN1870719A (en) * | 2005-05-23 | 2006-11-29 | 华为技术有限公司 | Method and system for receiving-end and source-end synchonous of broadcast TV service |
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2006
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1647552A (en) * | 2002-04-22 | 2005-07-27 | 诺基亚有限公司 | Media system, user terminal and method of providing content items relating to broadcast media stream |
| CN1812289A (en) * | 2005-01-26 | 2006-08-02 | 中兴通讯股份有限公司 | Apparatus for realizing network synchronization in personal cell phone based on IP |
| CN1870719A (en) * | 2005-05-23 | 2006-11-29 | 华为技术有限公司 | Method and system for receiving-end and source-end synchonous of broadcast TV service |
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| CN101202918A (en) | 2008-06-18 |
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Granted publication date: 20100414 Termination date: 20171211 |