FR2836318A1 - Two terminal packet switching network multimedia contents transmission having detector intercepting signaling information and processor analyzing information/converting/harmonizing terminal contents exchange - Google Patents

Abstract

The multimedia transmission system transmits between two terminal (T1,T2) across a packet switching network. A detector (C) intercepts terminal signaling information transmitted to a distant platform (P). A processor analyses and processes signaling information and provides a conversion to harmonize the contents exchange between the terminals.

Description

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 The present invention relates to a system for transmitting multimedia content between at least two terminals over a packet switched type network.

 The invention relates to telecommunications on the Internet type network and typically finds its application in the communication of multimedia content whatever the environmental conditions, that is to say whatever the parameters of the terminals between which communication is established, the quality of service constraints of the access network, etc.

 In general, the invention applies to systems operating according to any signaling protocol using an additional protocol SDP (Session Description Protocol in English terminology) intended to manage information in multimedia communications.

 The invention applies for example to systems operating according to the SIP protocol (Session Initiation Protocol in English terminology) which is used for signaling telephone or multimedia calls over the Internet. This protocol intervenes, before the transmission of voice or multimedia contents in the form of packets, to establish the parameters of a session between two terminals or, during a communication, to modify these parameters, or to end a communication. This protocol was the subject of a multimedia call establishment standard defined by the IETF (Internet Engineering Task Force), it

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 is used more and more and tends to supplant the standard H323 which is very widespread but more complex to use.

 The complementary protocol SDP (Session Description Protocol in English terminology) is used jointly with the SIP protocol, for the management of information in multimedia communications. The SDP type information is well known and corresponds for example to the address of a terminal, the audio and / or video encoders that it supports, the connection ports, the available bandwidth, etc. This SDP information are inserted into the body of the SIP signaling message, the header of which contains data relating to the routing of multimedia content, that is to say the addresses of the calling and called terminals, the priorities, the routing preferences with the address of the proxy server (s) crossed, etc.

 Even if, in the following description, reference is made only to systems operating according to the SIP protocol, it should not be forgotten that the invention can also be applied to other signaling protocols using the protocol complementary SDP.

 According to the SIP protocol, the signaling messages are transmitted by the terminals, between which the establishment of the communication is requested, via one or more servers of the "proxy" type which is responsible (s) for routing these messages in the network.

 When the terminals are not connected to the same proxy server, in the case where they do not belong to the same Internet domain for example, the proxy servers then communicate directly with each other.

 Currently, for a transmission of multimedia content to take place between two terminals, it is necessary that the parameters of the terminals are compatible. Thus, for example, it is necessary that the audio and video coders supported by the terminals are

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 identical or obey the same data transmission protocol, that the available bandwidth is compatible etc ...

 Nowadays, there are more and more different data transmission protocols and terminals of all kinds, such as for example personal computers (PC), PDA personal assistants (Personal Digital Assistant in English terminology), third generation mobile phones conforming to the UMTS standard, or interactive televisions, etc. Due to this growing diversity of protocols and terminals, it becomes important to be able to adapt the coding of multimedia content transported over the network so that the terminals can communicate in any circumstance, that is to say whatever the compatibility of their parameters.

 Existing proxy servers, used with the SIP protocol, are not adaptable and it is not possible to integrate new functionalities intended to manage and adapt the transmission of multimedia content.

 A CPL standard (Call Processing Language in Anglo-Saxon terminology) has been developed to allow certain actions to be performed based on certain SIP signaling information. These actions amount, for example, to redirect a communication to another terminal when the media supported by the called terminal does not correspond to the media supported by the calling terminal. In this case, the incompatibility problems between the terminals are resolved by transferring the call to another terminal compatible with the calling terminal. This standard is however very limited, it performs tasks based on certain information but it does not allow analysis and processing of signaling information in order to allow a

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 adaptation of the coding of the multimedia content transported, to simulate compatibility between the calling terminal and the called terminal.

 Another alternative is to build application servers. This type of server is grafted on top of the proxy server and processes signaling information to perform call management actions, such as transferring a call to another terminal for example. In this case, the application server returns the processed information to the proxy server so that the latter routes the information to allow the establishment of communication to the other terminal. However, these application servers still do not allow the establishment of a communication directly between two terminals which are a priori not compatible.

Indeed, they do not analyze or process the signaling information with a view to adapting the coding of the multimedia content exchanged, and simulating compatibility between the terminals.

 Also, the technical problem to be solved by the object of the present invention is to propose a system for the transmission of multimedia content between at least two terminals through a network of the packet switching type, which would avoid having to take into account the types of terminals used to communicate, by adapting the multimedia content transported in the network so as to simulate compatibility between the terminals.

 The solution to the technical problem posed is obtained, according to the present invention, from the fact that said system comprises a sensor intended to intercept signaling information, sent by each terminal, and to transmit it to a remote platform, said platform. remote comprising processing means capable of analyzing and processing said information of

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 signaling, then to provide conversion means intended to tune the multimedia content exchanged between said two terminals.

 Thus, the system according to the invention makes it possible, from the analysis of the signaling information and its processing, to provide suitable conversion means for tuning the multimedia contents transported in the network, and making them comprehensible by each terminal. Compatibility between the terminals is then simulated.

 Other characteristics and advantages of the invention will appear on reading the following description given by way of illustrative and nonlimiting example with reference to the appended figures which represent: FIG. 1, a block diagram of a first mode of embodiment of a system according to the invention, FIG. 2, a block diagram of another embodiment of a system according to the invention, FIG. 3, an example of application of a system according to invention.

 A multimedia content transmission system according to the SIP protocol is shown in FIG. 1. This system includes two terminals T1 and T2 intended to communicate with each other. These two terminals are not necessarily identical. Thus, for example, the terminal T1 can be a personal computer while the terminal T2 can be a PDA personal assistant or else a third generation mobile phone conforming to the UMTS standard.

In this case, the parameters of the two terminals are different, in particular the audio and / or video media they support are different, their available bandwidth is different, their session type is different, etc.

Whether the terminals are identical or not, if their

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 parameters are different, it is said that they are not compatible and, until now, a transmission of multimedia content has never been able to be established between two non-compatible terminals.

 In FIG. 1, each terminal Tl, T2 is connected to a proxy server referenced respectively 10 and 20. In this example, the terminals Tl and T2 belong to different Internet domains, respectively DA and DB, and are connected to proxy servers 10,20 freelancers who can communicate with each other and exchange signaling information from each terminal.

 Of course, when the terminals belong to the same domain for example, they can both be linked to the same proxy server.

 A traditional location server 30 makes it possible to associate an Internet address with a terminal and to route calls to this terminal.

 Finally, a sensor C makes it possible to intercept the signaling information originating from the terminals T1 and T2 and to transmit it to a remote platform P. In fact, the sensor C can be configured in such a way that it transmits to the platform P only the information of SDP type contained in the body of the signaling message.

 The remote platform P includes processing means capable of analyzing and processing the signaling information, and of providing conversion means, so as to allow the establishment of a communication between the two terminals T1 and T2 whatever whatever the circumstances, that is, whether the terminals are compatible or not.

 The platform P can for example be the platform of a network manager, or even the Internet services platform of an operator.

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 In the example of FIG. 1, the sensor C is positioned between the terminal Tl and the proxy server 10. This positioning of the sensor C makes it possible to intercept all the information originating from the terminal Tl such as the type of audio medium and / or video, IP address, available bandwidth, etc.

 The sensor C can however be positioned in other places in the system. In fact its positioning will depend on the information that a service provider, for example, wishes to intercept. Thus, in the case of FIG. 2, in which the same references as in FIG. 1 are used to designate the same elements, the sensor C is arranged between the two proxy servers 10,20. This positioning of the sensor C makes it possible in particular to control the inter-domain exchanges, or even, in certain cases, to mask certain values of parameters to avoid giving indications to the other domain, and thus to allow data exchanges in a totally transparent vis-à-vis the domains, that is to say that the real parameters of a terminal T1 of a domain DA are unknown to the terminal T2 of the other domain DB, and vice versa.

 Of course, it is quite possible to place this type of sensor C in several places in a multimedia content transmission system.

 The operation of such a system will be better understood with regard to FIG. 3 which represents an example of application consisting in providing, in the signaling message, information on the coding used for a multimedia application. In this example, two people wish to chat by videoconference via the Internet from their Tl and T2 terminals, which can be PC personal computers, personal assistants, third generation UMTS mobile phones, etc.

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 According to the SIP protocol, the calling terminal, T1 in the example, sends a conventional SIP signaling message, of the type, invites "representing the invitation to a session towards the terminal called T2. This message carries the information of SDP type relating to the session, i.e. the connection port, the type of content, the audio and video media used, the available bandwidth, etc.

 The message is sent to the proxy server 10 common to the two terminals in this example. The sensor C, positioned in the cut-off between the terminal Tl and the proxy server, makes it possible to intercept the signaling message. It records the information relating to the parameters of the terminal T1 and of the session to be established, then lets the message pass, without having modified it, to the proxy server 10.

 Then, the terminal called T2 in turn sends to the proxy server 10 a signaling message to confirm the opening of the session, with its own parameters. In this case, the information included in the signaling message is extracted from the proxy server 10 by the sensor C to be recorded.

 In a conventional architecture, if the video coders of the two terminals, for example, are not compatible, videoconferencing cannot take place, or then only in audio if the audio coders are compatible.

 In this system, the sensor C knows all the parameters of each terminal and, after comparison, it knows that the video coders, for example, are not compatible. It then transmits the signaling information, and more particularly the SDP type information contained in the body of the signaling message, to a remote platform P.

 This platform P includes processing means which analyze and process the information received. In

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 the example, the analysis of the information received leads to the conclusion that the parameters of the various video coders supported by the two terminals T1 and T2 are not compatible. After processing the information, these processing means also make it possible to provide conversion means intended to grant the coding of the multimedia content exchanged between the terminals T1 and T2, throughout the communication, without the terminals T1 and T2 be informed. To provide these conversion means, the processing means download them, from a remote server S for example.

 In a variant, the conversion means are for example stored locally on the platform P, in a database for example.

 In the example of FIG. 3, the processing means of the platform P download, from the remote server S, a video transcoder T which will make it possible to convert the video data coming from the calling terminal Tl to make them understandable by the terminal called T2, and vice versa.

 This video transcoder T is for example downloaded into an active node N of the network. This active node N is not only content to route the multimedia contents coming from the terminals T1 and T2, but for each frame of this session, containing the contents to be transported in the network, it decodes the video contents coming from one terminals and then re-encodes it in a format understandable by the destination terminal. The downloaded transcoder is thus able to adapt multimedia content from one format to another.

 In a variant, the transcoder T can also be registered on the platform P, or on another remote platform, or else it can be activated directly from the remote server S.

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 Once downloaded, the transcoder T is configured to establish an RTP link for example (Real Time Protocol in English terminology) with Tl and another RTP link with T2 depending on the signaling information intercepted by the sensor, such as the IP address or connection port for example. Possibly, thanks to the signaling information intercepted by the sensor, and in particular the information relating to the type of terminal which is included in the signaling message, the transcoder T can also be informed, by the sensor C or the platform P for example, on the specific characteristics of the terminal, such as the size of the screen for example.

 In an alternative embodiment, a database grouping all the possible terminals with their characteristics, updated regularly, can for example be inserted in the platform P, or in the remote server S, or else in another remote server any. Thus, by knowing the type of terminal, thanks to the intercepted signaling messages, the platform P can recover from this database the specific characteristics of this terminal, such as for example, the size of the screen, the number of colors, etc. ...

The transcoder can then be configured more precisely, taking into account these specific characteristics.

 The transmission of multimedia content from T1 to T2 is then split into two: a first transmission takes place from T1 to N then, after conversion of the content, a second transmission takes place from N to T2. Thus, during the videoconference the terminal Tl will transmit its information coded with its format, the video transcoder T downloaded in the active node N will convert this format to the format of the destination terminal T2 which will thus be able to receive the images, and vice versa. The multimedia content transmission system as described allows

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 therefore to make the two terminals T1 and T2 believe that they have the same video encoder, and thus not to inform them of the parameters of the terminal with which they communicate.

 Likewise, when the video transcoder T is recorded locally on a platform or on a remote server, it is configured to establish a first RTP link with T1 and a second link with T2. The communication between T1 and T2 is then established via the platform or the server respectively, in which (which) the transcoder is responsible for converting the video content exchanged.

 The system which has just been described with reference to the appended figures is only an illustration and is in no way limited to these examples. It finds multiple applications in particular in the transmission of multimedia content of all kinds, to make adaptations of audio / video coding on the fly applied for example to interactive television or to "video on demand" etc ...

It allows multimedia calls to be controlled and the content transported to be adapted according to the characteristics of the terminals. It also makes it possible to control network equipment using the information retrieved, and therefore to improve network management performance as well as QoS quality of service.

Thanks to such a system, terminal users no longer have to take into account the configuration of their terminal, they receive information whatever the parameters of their terminal.

Claims (5)

T2), and to transmit them to a remote platform (P), said remote platform (P) comprising processing means able to analyze and process said signaling information, then to provide conversion means intended for grant the multimedia content exchanged between said two terminals (T1, T2).  CLAIMS 1. System for transmitting multimedia content between at least two terminals (T1, T2) through a network of the packet switching type, characterized in that it comprises a sensor (C) intended to intercept signaling information, sent by each terminal (Tl, 2. System according to claim 1, characterized in that the processing means provide the conversion means by downloading from a remote server (S). 3. System according to claim 2, characterized in that the conversion means are stored in an active node (N) of said network. 4. System according to any one of the preceding claims, characterized in that the sensor (C) is arranged between one of the terminals (Tl, T2) and a proxy server (10). 5. System according to any one of the preceding claims, characterized in that said system comprising two proxy servers (10,20), the sensor <Desc / Clms Page number 13>  (C) is arranged between a terminal (T1, T2) and one of the two proxy servers (10) and / or between said two proxy servers (10, 20).