RU2367003C2 - Method of reporting on transfer rate of data from client during transmission of multimedia stream - Google Patents

Abstract

FIELD: physics; computer engineering.

SUBSTANCE: invention relates to the method of communication and coordination between a client with limited resources and a server during transmission of a multimedia stream, associated with delivery of data packets. To prevent packet loss at the client side due to the maximum possible rate of transfer of packets, the client sends a signal to the server, notifying on the maximum possible rate of transfer of packets. This possibility can be sent to the client using a mechanism for exchanging possibilities or using a multimedia stream transmission protocol. The client inserts a parametre, which indicates the maximum possible rate of transfer of data packets, in to the query sent to the server so at to undertake necessary action and regulate delivery rate of packets.

EFFECT: coordination of rate of transfer of packets between a client and a server for a successful session for processing without packet loss.

18 cl, 1 dwg

Description

FIELD OF THE INVENTION

This invention, in General, relates to the transmission of a multimedia stream and, more specifically, to signaling (message) about the possible transmission speed of client packets in the transmission sessions of the multimedia stream.

State of the art

Three participants are involved in the multimedia stream transmission service: a streaming server, a streaming client, and a core network that provides connectivity between the server and the client. The server provides functionality for delivering to the client the contents of a multimedia stream. To this end, the client and server communicate with each other over the network, affecting the possible exchange method, the method of coordinating the delivery of content, controlling the delivery of content, etc. Such an exchange of information can be accomplished through well-defined network protocols.

To transmit a multimedia stream, a session must be established and started successfully, and the server and client must support a minimum set of protocols that are selected by the service as standard protocols. An example of such a service can be found in 3GPP TS 26.234 V5.1.0, "Transparent End-to-End Packet Switched Streaming Service (PSS); Protocols and Codecs (Release 5)", June 2002, hereinafter referred to as TS 26.234). Examples of such a set of protocols were used in 3G, PSS - SDP (see, for example, IFTF TFC 2327: "SDP: Session Description Protocol", Handley et al., April 1998), RTSP (see, for example, IETF RFC 2326: " Real Time Streaming Protocal (RTSP), Schulzrinne et al., April 1998) and RTP / RTCP (see, for example, IETF RFC 1889: RTP: A Transport Protocol for Real-Time Applications, Schulzrinne et al., January 1996).

In a stream transfer service, a client may be an application running on a device that is resource limited. It may be that the client is not able to process more than a certain number of packets arriving at its receiving node.

In most services, the server and client negotiate an available frequency band to deliver content. However, if the client is a resource-limited device, this fact also has a limit on the maximum number of packets that it can actually capture from the receiving node. Most of the time this restriction was not reported.

One specific case where this can be a problem is direct sound reproduction (without intermediate conversions of received signals), where data can be delivered at a packet rate of 50 packets per second (for example, AMR-NB codec with 1 AMR-NB frame / useful load). If there are two sound sources delivering data to the same client at the same time (or in another case where there are also video sources delivering media packets at a packet rate of 50 packets per second, in addition to the sound source), then the transmission speed packets should be 100 packets per second, which might be too high for the client to handle lossless packets.

Therefore, in order to successfully complete a session, there is a definite need to negotiate this value between the client and server.

SUMMARY OF THE INVENTION

The present invention provides a method for communicating and negotiating between a resource-limited client and a server in a multimedia stream transmission service regarding the delivery of data from a server to a client. In particular, the present invention provides a method for reporting the maximum possible packet rate of a client to a server so that the server does not exceed this maximum packet rate and does not cause packet loss on the client side or an abnormal failure of the client’s mobile device. The method can be performed using a capability exchange mechanism or using a media stream transmission control protocol.

Thus, the present invention provides a method for controlling the delivery of a data stream in a multimedia streaming network containing a server for transmitting data streams to a client at a data packet rate, characterized in that

announce in the message in the client the maximum possible data transfer rate; and

send a message to the server.

According to the present invention, the message contains a request sent to the server through the capability exchange mechanism, and the request includes a capability profile for indicating the maximum possible data rate. The maximum possible data rate is indicated by the capability parameter in the capability profile, and the capability parameter is included in the RTSP DESCRIBE request.

In addition, the maximum possible data transfer rate is indicated in the capability information resident on the capability exchange server, the request containing a URL pointing to the capability information. The server responding to the request searches for the capability parameter on the capability exchange server through the capability exchange mechanism to control the transmission speed of the data packets.

The server can adjust the data packet rate based on the capability parameter in order to match the maximum possible data rate in the client.

Alternatively, the message is transmitted to the server via the media stream transmission control protocol, and the message contains a request including an RTSP header extension indicating the maximum possible data rate.

Brief Description of the Drawings

The drawing depicts an advertisement by a customer as part of the communication and approval process of this invention.

DETAILED DESCRIPTION OF THE INVENTION

The method of communication and coordination between a client and a server in a multimedia stream transmission service regarding adaptation of a data delivery process according to this invention can be performed through a capability exchange mechanism or through a Multimedia Stream Transfer Control Protocol. The Multimedia Stream Transmission Control Protocol is strictly defined and standardized within the context of the service. A capability exchange mechanism is known in the art and therefore is not part of this invention. Adaptation of the data delivery process is based on the maximum possible transmission rate of packets limited in client resources. The client uses the maximum packet rate (MaxPacketRate) (packets per second) to determine the maximum number of packets that can be processed in a given time interval.

After the message is executed through the exchange of capabilities, the procedure can be based on a standard, as formulated, for example, in TS 26.234.

Let the attribute "MaxPacketRate" be defined in the RDF (Consortium Standard for WWW resource description) Schema dictionary to report the value of the maximum possible packet transfer rate to the client. The attribute is defined in blocks (modules) of packets per second.

The following is the communication procedure:

- The client declares the value of MaxPacketRate as an opportunity parameter in its opportunity profile. For example, a client sends an RTSP DESCRIBE request to a server with a URL pointing to client capability information resident on the capability exchange server.

- The server searches for a client capability statement on the opportunity exchange server through the opportunity exchange mechanism. The application has a part for client stream transfer capabilities, as shown in the drawing. Bold lines in the application represent the maximum possible packet rate of the client. Having the MaxPacketRate value obtained, the server has information about the current packet transmission rate to regulate the maximum possible packet reception rate of the client. The server can then adjust the maximum transmission rate of packets delivered to the client. However, this is sent to the server in order to take the necessary action and adjust the delivery of packets.

After the message has been executed through the Multimedia Streaming Transmission Control Protocol, the client can use the strictly defined optional RTSP tag and the RTSP header extension (see, for example, IETF RFC 2326).

Let "x-maxpacketratesupport" be the optional RTSP tag.

Let "x-maxpacketrate" be the RTSP header extension defined in modules per second.

The client is supposed to know in advance the RTSP (Universal Resource Locator) URL for a multimedia session.

The following is the communication procedure.

The client declares a MaxPacketRate value in a DESCRIBE request sent with an x-maxpacketrate value that states:

Client-> Server:

DESCRIBE rtsp: // foo / twister RTSP / 1.0

CSeq: 1

Require: x-maxpacketratesupport

x-maxpacketrate: 70

- If the server does not use the maximum possible packet rate of the client, the server responds to any RTSP 551 with an “Option Not Supported” message containing an “Unsupported: x-maxpacketrate” line, or the RTSP 200 with an OK message containing “Unsupported : x-maxpacketrate "line. By using the RTSP "Require" header, the client understands whether the server accepts the parameter in the account or not. If the server accepts the parameter into the account, then the client can report updates to the maximum possible packet rate during the session using any RTSP message body.

If the server uses this parameter, the server checks the RTSP request and sees that it contains a strictly defined x-maxpacketrate value. It retrieves the value from the RTSP request message.

After recognizing the MaxMacketRate value in the requests sent by the client, the server uses the value to adjust the maximum transmission rate of packets delivered to the client. However, this is up to the server, in order to take the necessary action and make adjustments related to the delivery of packets.

It should be noted that the maximum input rate for packets coming from a network interface, which is a viable client device, can be defined as MaxPacketRate in the RDF Schema dictionary, but it can be named differently. Similarly, “x-maxpacketrate” or another name may be used in an RTSP message as long as it can be used to determine the maximum input rate for packets coming from a network interface that is a viable client device. "x-maxpacketratesupport", or another name, can be used in the RTSP "Require" header as long as it can be used to determine if the server can understand and accept the maximum input packet rate header transmitted in any RTSP message body, sent by the client device.

Claims (18)

1. A method for controlling the delivery of a data stream in a multimedia streaming network, including a server for providing data streams to a client at packet data rates, wherein
declare in the client’s message the maximum possible input rate of the data delivered to the client; and
transmit a message to the server to adjust the server said data rate for the client. 2. The method according to claim 1, in which the message contains a request sent to the server via the capability exchange mechanism, and the request includes a capability profile for indicating said maximum data rate. 3. The method according to claim 2, wherein said maximum possible data rate is indicated by an opportunity parameter in the opportunity profile. 4. The method of claim 3, wherein the capability parameter is included in the RTSP DESCRIBE request. 5. The method according to claim 4, in which the aforementioned maximum data transfer rate is indicated in the capability information resident on the capability exchange server, and the request includes a URL pointing to the capability information. 6. The method according to claim 5, in which the server responding to the request retrieves the capability parameter on the capability exchange server through the capability exchange mechanism to control the packet data rate. 7. The method according to claim 6, in which additionally
the server adjusts the packet data rate based on the capability parameter in order to match said maximum possible data rate in the client. 8. The method according to claim 1, in which the message is transmitted to the server via the transmission control protocol of the multimedia stream. 9. The method of claim 1, wherein the message comprises a request including an RTSP header extension indicating said maximum data rate. 10. A client device in a network for transmitting multimedia streams, including a server for transmitting data streams to a client at a packet data rate, comprising
means for announcing in the client’s message the maximum possible input data rate delivered to the client; and
means for transmitting a message to the server for the server to adjust said data rate for the client. 11. The client device of claim 10, wherein the message comprises a request sent to the server via a capability exchange mechanism, and the request includes a capability profile for indicating said maximum data rate. 12. The client device of claim 11, wherein said maximum possible data rate is indicated by an opportunity parameter in the opportunity profile. 13. The client device of claim 12, wherein the capability parameter is included in the RTSP DESCRIBE request. 14. The client device of claim 13, wherein said maximum possible data rate is indicated in capability information resident on the capability exchange server, and the request includes a URL indicating capability information. 15. The client device of claim 14, wherein the server responding to the request retrieves the capability parameter on the capability exchange server through the capability exchange mechanism to control the packet data rate. 16. The client device according to clause 15, and
the server adjusts the packet data rate based on the capability parameter in order to match said maximum possible data rate in the client. 17. The client device of claim 10, in which the message is transmitted to the server through the transmission control protocol of the multimedia stream. 18. The client device of claim 10, wherein the message comprises a request including an RTSP header extension indicating said maximum data rate.