WO2005006685A1

WO2005006685A1 - Method for prebuffering of multimedia streaming data

Info

Publication number: WO2005006685A1
Application number: PCT/SE2004/001112
Authority: WO
Inventors: Jonas Lindberg; Daniel Nilsson; Martin GÜLL
Original assignee: Telia Ab (Publ)
Priority date: 2003-07-10
Filing date: 2004-07-07
Publication date: 2005-01-20
Also published as: SE0302040L; SE0302040D0

Abstract

A system and procedure to control buffering of streaming data, where the aim is to show/present a more efficient buffering method which admits streaming of streaming data without delay due to initial filling of local data buffer. This is achieved by, before a streaming service is initialized, an MMS is initially transmitted to the user which holds buffer data as well as part information about the data flow as such. This means that the streaming client can start streaming of buffer data without delay. The system for storing of streaming data consists of a wireless tele- and data communication network 102 and a user 104 with a terminal 106. In the network is that part where a requested service A is, which consists of a streaming server 108 and an MMS-server 110. The terminal 106 which uses the service A consists of an MMS-client 202, a streaming client 204, a streaming buffer 206 and a presentation/display unit 208.

Description

METHOD FOR PREBUFFERING OF MULTIMEDIA STREAMING DATA

TECHNICAL FIELD The present invention relates to a method to control buffering of streaming data in a wireless tele- and data communication network; more exactly to achieve streaming of streaming data without delay.

PRIOR ART

It is previously known of methods to control streaming of multimedia data which are divided into smaller packets.

One experienced problem at use of media which are subject to streaming is the buffering which has to be done initially. The buffering is necessary to handle variations, if any, in the channel/network, such as changes in bandwidth and jitter (delay variation), which may result in loss of packets etc. In case of problems, the user, thanks to the buffer, has time to request re-transmissions of lost information/data .

The size of the buffer, and by that the time the initial buffering will take, is directly depending on how big these variations in the channel are, and in a narrow band network (for instance GPRS) these are rather big. The player for that reason may need to buffer up to about 20 seconds before it can start streaming of the material to get a streaming without interruptions .

Pre-buffering has not been done in any previously known product. Neither has MMS been used in this way. It is only with MMS which it in the mobile environment will be possible to transmit pre-buffering to terminals of this kind. The solutions which exist today are initiated by the client and after that a session with streaming server which starts streaming back the rest of the information. Earlier attempts at solution in most cases have involved that one has tried to improve the storing at the streaming client by the streamed information being placed in a buffer.

WO 0211398 describes a method to control streaming of multimedia data, which is divided into smaller packets. The first packet includes specific information about the streaming session in question as well as a first streaming component. Streaming of the streaming session by that can be started directly without any delay for loading of initial data to buffer.

SUMMARY OF THE INVENTION

One problem which the present invention solves is that at use of media which are being streamed, initial buffering need not be done. The size of the buffer and by that the time the initial buffering will take depends on how big these variations in the channel are .

One method is that a first packet includes specific information about the streaming session in question as well as a first streaming component. Streaming of the streaming session by that can start without delay for loading of initial data to the buffer.

The present invention transmits the initial buffer information which is necessary for the streaming user via MMS to the user's terminal before the user starts utilizing the service. When the user shall start the session, the in the MMS enclosed information is used at the same time as the user starts streaming remaining data from the streaming server in order to refill the buffer again. The invention implies that the streaming server transmits the initial buffer information which is necessary for the streaming user via MMS to the user's terminal before the user starts using the service. When the streaming user shall start the session, the in the MMS enclosed information is used, which can be used directly, at the same time as the user starts streaming remaining data from the streaming server to refill the buffer again.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more details in the following with references to enclosed drawings, in which Figure 1 shows a comprehensive picture of the system for storing of streaming data, Figure 2 shows a terminal ,

Figure 3 shows a procedure for storing of streamed services,

Figure 4 shows short video sequence where all I-frames are transmitted via MMS, and other data (P-frames) are streamed,

Figure 5 shows long video sequence where all I-frames are transmitted via MMS asymmetrically, and other data (P- frames) are streamed.

DESCRIPTION OF PREFERRED EMBODIMENTS

Figure 1 shows a system 100 for storing of streaming data which consists of a wireless tele- and data communication network 102 and a user 104 with a terminal 106. In the network is that part where a service A looked for is, which consists of a streaming server 108 and an MMS-server 110.

In Figure 2 the terminal 106 which uses the service A is shown. The terminal includes i.a. an MMS-client 202, a streaming client 204, a streaming buffer 206 and a display/presentation unit 208. In Figure 3 a procedure 300 for storing of services is shown. According to the present invention, the procedure includes the following steps: Step 1, 302, of the procedure amounts to that a user 104 receives an MMS notification with an arbitrary greeting message and an appendix in which the initial streaming buffer "MMS PreBuf" and a streaming pointer are. The streaming pointer is an ordinary rtsp-link and an example of this is: "rtsp : //server. com. /file .mp4" .

In step 2, 304, the user 104 decides to start the streaming session; the service is in this way activated in the MMS client 202 by a user 104 requesting open the appendix of the MMS, at which the streaming client 204 automatically starts. The MMS client 202 then transmits "MMS PreBuf" (buffer data and streaming link) to the streaming client 204.

In step 3, 306, the streaming client 204 puts the enclosed information "MMS PreBuf" in its streaming buffer 206.

In step 4, 308, the user 104 then initiates a session with the streaming server 108 "RTSP GET", which starts streaming back the rest of the information.

In step 5, 310, information "RTP data" will reach the streaming client 204 from the streaming server 108.

In step 6, 312, "RTP data" is put in the streaming buffer

206.

At point A: The data which are enclosed in the MMS can be of just any kind. In the case of/with media (video/audio) it can, for instance, be the first seconds of the sequence.

The streaming buffer 206 should in this case correspond to about 15 s streaming. In case that a bit rate of 64 kbit/s is used, it will correspond to an amount of data of 120 kB . At point B: When the streaming user transmits the initial buffer data to the streaming buffer, this will "believe" that it is only ordinary data, and has no knowledge of that these have been streamed or been loaded from the memory. In the same way the new streamed information just can be refilled into the streaming buffer without any problems occurring.

At point C: When the streaming client 204 shall start streaming the rest of the information, there is support in RTSP to jump forward in an amount of data. In this way it will be easy to start streaming data from the point of time which is identical with the length of the buffer. For instance, if the buffer is 15 s, then the streaming server 108 will have a message to start streaming data from point of time 15 s, instead of from the beginning.

This invention fits well together with video messages, i.e. MMS with video, or for subscription services where the receiver will have a notification before he/she makes use of the service.

The solution also should be possible to apply in fixed environments where the user, for instance via e-mail, will have the initial buffer enclosed as an appendix.

The line of reasoning above shows that the invention can be implemented with smaller modifications in just any streaming software .

The only modification which might need to be done, is that the streaming client reads an amount of data from the memory into the buffer, finds out the length of this sequence, and then starts the streaming session as usual. Most types of media often can be divided into high and low prioritized data. High prioritized data can be compared to a frame which has to exist to keep up details (low prioritized data) . For instance a video sequence consists of two types of frames; I -frame (Intra-frame) and P-frame (Predicted frame) . An I-frame includes all information to show a complete picture, whereas a P-frame only includes changes from previous picture. With this technology it will not be necessary to transmit I-frames continually to achieve moving pictures, but it may perhaps be sufficient that each 10:th frame is of I-type; the frames in between can be of P-type. A pattern similar to IPPP...IPPP might be achieved.

One way in which this invention might be used is by transmitting streaming data in the following way: By using a combination of two technologies, MMS and Streaming, in order to guarantee that the video client in the mobile terminal has access to high prioritized data on right occasion. By using MMS as an initial notification for the media, it will be possible to transmit such a message with any amount of high prioritized information, for instance any number of I-frames. The video client in this way has a lead at the video decoding, and the streaming protocol will have more time to secure that the rest of data actually will arrive.

In the following text, the example above with different frames will be used to simplify the explanation.

The invention can be utilized in different ways: One alternative is when the video sequence is short; then all high prioritized information (I-frames in the example) is transmitted in the MMS message. The streaming part only need to concentrate on streaming the low prioritized information (P-frames in the example), see Figure 4. A second alternative is when the video sequence is long; then an asymmetrical transport of information is created. This is done by the high prioritized information being displaced in time. If problems occur with the transmission of I-frames, or if high prioritized data become faulty, the application/system will have more time to correct this, see Figure 5. To the left in Figure 5, normal flow of information in a system. To the right in Figure 5, notice the displaced high prioritized information, I-frame, displaced in the streamed data.

Another example is if the system now, for instance, decodes frame p ₄, and frame I_n+2 should be faulty transmitted, then the system will have ~n times more time to try to transmit l_n+2 compared with ordinary streaming.

The method can in principle be used in all video applications where the system uses some kind of notification (for instance e-mail) .

But of particular interest is in mobile connections (GPRS/UMTS) where there is a very limited bandwidth and where one for some reason wants to do the streaming over a Best-Effort channel. In connection with that UMTS will enter into the market, it also will be possible to have more new types of services realized, such as video. It may be expensive to run all video over UMTS by means of QoS, which moreover is not accessible in GPRS. There will be more services which have to be executed over the cheaper Best-Effort-channels.

In the first alternative above, where the sequence is rather short, this method might be possible to use at a short video trailer to certain persons. These then can at first see a "still-slideshow" of the sequence. In case the user then instead wants to see the whole sequence, the system only needs to stream over the lacking P-frames; in that way the quality of the sequence is increased at the same time as the bandwidth is reduced.

The solution also would be possible to use in other systems where separation of high and low prioritized information is made. For example at building of a security solution where some part of the information is transmitted via MMS (for which the system can charge, and identify the user) which is necessary to make it possible to use the rest of the information.

Claims

PATENT CLAIMS

1. System (100) to control buffering of streaming data in a wireless tele- and data communication network, c h a r a c t e r i z e d in that the system includes: a terminal (106), a network (102) at which the network includes: a streaming server (108), an MMS-server (110), that in the network is that part from which streaming data are derived, and that the terminal includes means (202, 204, 206) to buffer a first time interval of streaming data, includes specific information about the streaming session in question together with a arbritary amount of high prioritized information before a user (104) of a terminal (106) starts to utilize service the in question.

2. System as claimed in patent claim 1, c h a r a c t e r i z e d in that the terminal includes: An MMS client (202), a streaming client (204), a streaming buffer (206), and a presentation/display unit (208).

3. Terminal 106 in a system 100 to control buffering of streaming data in a wireless tele- and data communication network, c h a r a c t e r i z e d in that the terminal (106) which includes: An MMS client (202), a streaming client (204), a streaming buffer (206), at which the terminal handles buffering of a first time interval of streaming data, includes specific information about the streaming session in question together with a arbritary amount of high prioritized information before a user (104) of a terminal (106) starts to utilize service the in question.

4. Procedure (300) for a streaming session, to control buffering of streaming data in a wireless tele- and data communication network, c h a r a c t e r i z e d in that a system (100) which includes: A terminal (106), a network (102), at which the network includes: A streaming server (108), an MMS server (110), that in the network are selected information from which streaming data are derived, at which the terminal includes means (202, 204, 206) to buffer streaming data, includes specific information about the streaming session in question together with a arbritary amount of high prioritized information before a user (104) of a terminal (106) starts to utilize service the in question, and means to show information (208), that the procedure consists of buffering a first time interval of streaming data, to show/display the first information on the display unit, and at the same time as the first information is shown on the display unit, new streaming data are transmitted.

5. Procedure as claimed in patent claim 4, c h a r a c t e r i z e d in that before a streaming service is initialized, an MMS is initially transmitted to the terminal which has requested the service; the MMS includes buffer data as well as information about the data flow as such, that the streaming client can start streaming of buffer data without delay.

6. Procedure as claimed in patent claim 4, c h a r a c t e r i z e d in that the procedure includes: A first step (302) that the terminal (106) receives an MMS- notification to the streaming session, a second step (304) to activate transmission of buffer data from a MMS-client (202) to the streaming client (204), a third step (306); the streaming client (204) puts the enclosed information in its streaming buffer (206) , a fourth step (308); the terminal initiates a session with the streaming server (108) which starts streaming back the rest of the information, a fifth step (310) ; the streaming server (108) transmits information to the streaming client (204), a sixth step (312) ; the streaming client puts the information in the streaming buffer (206) .

7. Procedure as claimed in any of the previous patent claims, where a terminal includes a video client, the streamed information is divided into high prioritized data, I-frames, and low prioritized data, P-frames, c h a r a c t e r i z e d in that high prioritized data are transmitted via a separate medium, whereas low prioritized data are transmitted over a standard channel, in order to after that show high and low prioritized data in correct sequence continually in the terminal.

8. Procedure as claimed in patent claim 7, c h a r a c t e r i z e d in that high prioritized data are transmitted via MMS and low prioritized data are transmitted via streaming.

9. Procedure as claimed in patent claim 8, c h a r a c t e r i z e d in that MMS is used as an initial notification for the medium.

10. Procedure as claimed in any of the patent claims 8 or 9, c h a r a c t e r i z e d in that just any amount of high prioritized data can be transmitted in an MMS.

11. Procedure as claimed in any of the patent claims 8 to 10, c h a r a c t e r i z e d in transmitting all high prioritized data via MMS at short video sequence.

12. Procedure as claimed in any of the patent claims 8 to 11, c h a r a c t e r i z e d in transmitting asymmetrical high prioritized data via MMS a long video sequences.

13. Computer program including program steps for execution of the steps in a procedure according to any of the patent claims 1-12.

14. Computer with readable medium including instructions for execution of the steps in procedure according to any of the patent claims 1-12.