WO2016156386A1

WO2016156386A1 - System for broadcasting audio and/or video content via a local wifi network, and devices implementing the method

Info

Publication number: WO2016156386A1
Application number: PCT/EP2016/056903
Authority: WO
Inventors: Frédéric BEAUCHAMP
Original assignee: Tdf
Priority date: 2015-03-30
Filing date: 2016-03-30
Publication date: 2016-10-06
Also published as: FR3034610A1; FR3034610B1

Abstract

The invention relates to a method for transmitting linear audio and/or video content from a broadcast server to a plurality of terminals by using the Wifi network. First, the broadcast server transmits the requested content to a first terminal, in the form of a data packet stream. Next, a second terminal transmits a request to the broadcast server to receive the same content via the Wifi network, the reception of said request triggering the transmission, by the broadcast server, of a message identifying the first terminal as the terminal transmitting said content. The second terminal then transmits a request to receive said content to the first terminal in order to receive said content via a peer-to-peer link. In this way, part of the load of managing the transmission of broadcast content is transferred to the level of the network terminals, and the resources of the Wifi server are thus used less.

Description

System for broadcasting audio and / or video content via a local Wifi network, and apparatus implementing the method.

1. Field of the invention

Provided is a method of broadcasting a service stream transmitted by a head end to a plurality of terminals, the service flow carries audio and / or video content cut into data packets and intended to be reproduced at the terminals. The present invention relates more particularly to the fact that the different packets are sent by a streaming server to each terminal through a local Wifi network.

2. Prior Art

Nowadays, there are many ways to achieve the transmission of digital content, among which the techniques based on standards from consortia DVB (English "Digital Video Broadcast" for "Digital Video Broadcasting"). Other content transmission techniques are also used with networks operating using the IP protocol (from the English "Internet Protocol" for "Internet Protocol"). These contents are transmitted using a material medium (a cable for example) or intangible (a wireless network, usually radio).

Many people use their terminal to receive real-time services such as television channels, weather or traffic information, stock quotes, the state of train arrivals, etc. These terminals communicate very generally via WiFi. which is a widespread standard nowadays. By selecting a service delivering a linear content, ie intended to be reproduced in real time or with a very slight delay as soon as it is received, the user asks his terminal to establish a unicast link with a streaming server via a Wifi point detected at proximity. The service references the audio and / or video content to be transmitted in real time and the terminal receives the packets carrying this content.

In some cases, many terminals are present in an area managed by a streaming server. This is particularly the case where travelers are in the same vehicle, a train, a bus or a boat, or in a waiting room or a theater, for example. The list of available services being limited, a number of terminals connect to the streaming server to receive the same content.

To save the streaming server the management of many unicast links, a simple solution is to transmit to the terminals the multicast content on the Wifi network. However, it turns out that this network does not support such a mode of communication, and there are frequent data losses.

US 2012/066495 - HAO JACK published March 15, 2012 describes a system for transmitting encrypted content, through a wireless network. A device receives a download request from a user terminal and transmits the requested content in encrypted form over a Peer To Peer link.

US 2007/183342 - WONG HANSON, published August 9, 2007, describes a method for transmitting content over a P2P network from a platform. This document teaches chaining in that a terminal receives streaming content from a previous terminal and retransmits it streaming to a next terminal.

There is therefore a real need to implement a means of broadcasting linear audio and / or video content that uses the support of the Wifi network and that consumes a minimum of the resources of the streaming server.

3. Objectives of the invention

The present invention provides a solution that does not have the drawbacks described above, while offering the advantages listed below. above. The proposed solution reduces the workload of the streaming server by reporting it to the terminals.

4. Presentation of the invention

The present invention provides a method of transmitting a linear content from a broadcast server to a plurality of terminals using the Wifi network. The method comprises a prior step of receiving said content by the broadcast server using a broadcast network a step of transmission by the broadcast server to a first terminal of said content in the form of a packet stream of data, a step of transmission by a second terminal of a request to the broadcast server to receive, by the Wifi network, the same content, said step of transmitting said request triggering a transmission step, by the server broadcast, a message identifying the first terminal as the transmitting terminal of this content, the second terminal then sending a request to receive this content to the first terminal to receive said content through a peer-to-peer link.

In this way, the broadcast server does not manage all the linear content transmission streams but entrusts some of them to the terminals connected to the Wifi network, thus freeing up the resources of the broadcast server which can use them for other tasks. .

According to a first embodiment, the method comprises a step of managing a list at the broadcast server, said list associating a given content with at least one identifier of a terminal that receives from the broadcast server this content. The step of transmitting a message, by the broadcast server, in response to a request sent by the second terminal to receive this content, comprises a substep of selection by the broadcast server selected in said list an identifier of a terminal that is associated with the requested content.

In this way, the broadcast server quickly determines the terminals capable of transmitting the requested content.

According to another embodiment, the method comprises a step of transmitting a message from a terminal to the broadcast server indicating that this terminal does not have the resources necessary to transmit to another terminal the content currently received and associated in the list, this information being entered into the list managed by the broadcast server, such a terminal not being selected by the broadcast server to transmit the content to another terminal.

In this way, the broadcast server does not indicate to a terminal an identifier of a terminal that actually receives the requested content but does not have the resources necessary to retransmit it.

According to another embodiment, the method comprises a step of transmitting a message from a terminal to the broadcast server indicating that this terminal has the resources necessary to transmit to another terminal a plurality of content currently received and associated in the list, this information being entered into the list managed by the broadcast server, such a terminal being selected by the broadcast server to transmit one of the contents to another terminal.

In this way, the method manages terminals having the necessary resources to retransmit several contents at the same time.

According to another embodiment, the method comprises the following steps:

transmission by a requesting terminal of a content to a so-called "previous" terminal of a request to receive this content by a peer-to-peer link,

transmission by the preceding terminal in response to the request of a message indicating to request this content to a so-called "next" terminal, the previous terminal already transmitting this content to the next terminal,

repetition of the two previous steps, the next terminal becoming the preceding terminal, until a subsequent terminal transmits said content at the requesting terminal.

In this way, true content transmission chains are formed to broadcast the different contents using peer-to-peer links. The dynamic management of the peer-to-peer links between terminals for transmitting the content is done by the terminals themselves and not by the broadcast server.

According to another embodiment, the method comprises a step of counting the iterations, the following steps are triggered when the number of iterations reaches a determined maximum value:

- stop iterations,

- Search by the broadcast server of another first terminal receiving the content of the server,

- sending by the requesting terminal a request to receive this content to the other first terminal to transmit said content.

In this way, the broadcast server manages the terminal chains transmitting the same content and stops the iterations within a chain when it includes a maximum number of terminals.

According to another embodiment, the message transmitted by the broadcast server in response to a request to receive a content by the Wifi network comprises a list of several terminals identified as terminals receiving said content, the requesting terminal of a content s'. addressing a first terminal of the list to receive this content and exploring a succession of terminals from this first terminal of the list by peer-to-peer links, a new request to receive this content to another first terminal of the list being triggered by the requesting terminal when the number of iterations reaches a determined maximum value without being able to receive the content. In this way, each requesting terminal manages its own chain of terminals to receive the requested content and does not mobilize the resources of the broadcast server for this management.

According to another embodiment, the requesting terminal issues a request to receive the requested content directly from the broadcast server when no terminal of terminal successions starting with the first terminals of the list transmitted in the message, is available to transmit the requested content. In this way, even if no terminal already receiving the requested content is available, the broadcast server can still directly transmit this content.

According to another aspect, the invention relates to a broadcast server receiving by means of reception of linear contents through a broadcast network and a communication means for transmitting and receiving messages to a plurality of terminals through a point of access. Wifi access. The communication means transmits to a first terminal and at its request a content in the form of a stream of data packets. The communication means receives from a second terminal a request to receive this same content by the Wi-Fi network, the reception of this request triggering the transmission by said communication means of a message identifying the first terminal as transmitting device of this content.

According to another aspect, the invention relates to a terminal intended to receive at least one linear audio and / or video content originating from a broadcasting network comprising at least one data storage memory of the at least one content and one medium. Wi-Fi communication to send and receive messages through a Wifi point. The communication means transmits to a broadcast server a request to receive the at least one content in the form of a stream of data packets. The communication means receives in response said data packets, said packets being stored in the data memory, said means subsequently receiving a request from another terminal to transmit to said other terminal said data packets previously stored in memory, said means transmitting in response said packets extracted from the data memory.

According to another aspect, the invention relates to a program product computer downloadable from a communications network and / or stored on a computer readable medium and / or executable by a central unit. Said computer program product comprises program instructions for implementing at least one step of the content transmission method as described above and in any one of the embodiments.

5. List of figures

Other features and advantages of the invention will appear more clearly on reading the following description of a particular embodiment, given as a simple illustrative and nonlimiting example, and the appended drawings, among which:

FIG. 1 shows an example of the main elements composing a system for broadcasting services to terminals,

FIG. 2 represents an example of a flowchart of the main steps for the implementation of a method according to an embodiment,

FIG. 3 represents a first state of the communication flows between terminals and the streaming server at a given instant,

FIG. 4 represents a second state of the communication flows between terminals and the streaming server at another given instant,

FIG. 5 illustrates the contents of a table for managing the broadcasting of services within a Wifi network.

6. Description of an embodiment of the invention

6.1 General principle

The invention relates to a method for transmitting a linear content of a streaming server to a plurality of terminals using the Wifi network. Initially, the streaming server transmits to a first terminal the requested content in the form of a stream of data packets. Then, a second terminal issues a request to the streaming server for receive the same content via the Wi-Fi network, the reception of this request triggering the transmission by the streaming server of a message identifying the first terminal as sending device of this content. The second device then sends a request to receive this content to the first terminal to receive said content by the first terminal through a peer-to-peer link, and no longer by the streaming server.

In this way, part of the management load of broadcast content transmissions is transferred to the terminals of the network and thus the resources of the streaming server are less used.

6.2 Particular embodiment

The diffusion system illustrated in FIG. 1 notably comprises an HLS encoder 1 which receives a plurality of streams carrying services. These services are, for example, audio and / or video channels, applications (teleshopping, traffic information, weather reports, ....). These services provide linear contents, that is to say, subject to the temporal constraint of being reproduced in near real time, the term "quasi" meaning that there may be a slight time difference between the emission by the head of network and reproduction at the terminal, such an offset being generally a few seconds, or even a few tens of seconds. The data of the services are presented at the input of the encoder HLS 1 (acronym of "HTTP Live Streaming") which segments the audio and / or video content in a succession of packets (or "chunk" - this name will then be used in the rest of the document). Segmentation techniques are known per se, for example the HLS, DASH or Smooth Streaming algorithms. Each chunk has a file data structure containing a payload (for example, audio and / or video data, with data synchronizing their reproduction - typically "timestamps"), a reference, and a source identifier ( typically the identifier of the associated service). In the case of audio and / or video content, the stream is generally of the MPEG type. Each chunk contains a succession of packets constituting an audio and / or video stream. The duration of reproduction of the audio and / or video data of each chunk of the same service is the same, typically a few seconds. Each chunk is organized into a file containing a set of audio and / or video data packets, and is identified chronologically by a reference. Having a nature of independent files, the chunks can be transmitted according to various ways and received non-chronologically by the terminal. The reference of each chunk makes it possible to reconstitute the sequencing of the data and to reproduce the content correctly.

The segmented contents of the services are transmitted to a server PUSH 2 to be broadcast to at least one broadcast server 3, which is the French translation of "streaming server", it is the Anglo-Saxon word that will subsequently be used . The encoder HLS 1 and the server 2 constitute a broadcast headend. Broadcasting can be carried out by digital television broadcasting networks, such as DTT networks, implementing the DVB-T standard ("Digital Video Broadcasting - Terrestrial" for "digital terrestrial video broadcasting"). Broadcasting of data packets is specified by standards so as to be received by a large number of receivers of any type. The network (terrestrial, satellite or cable) broadcasts audio and / or video content in data streams more commonly referred to as "service" and data intended to reference them. These data are for example defined in the DVB-SI ('Digital Video Broadcast - Specification for Service Information') or 'Digital Video Broadcasting - Specification of Service Data' specification EN 300 468 VI.3.1 (published by ETSI ) and the "Information technology - Generic coding of moving pictures and associated audio: System" standard, referenced MPEG ISO / IEC 13818-1, 2nd edition published on December 1, 2000.

The streaming server 3 has a central unit 4, a program memory 5 and a storage unit 6, typically one Hard disk. The program memory 5 contains in particular a distributed service management application which constitutes one of the objects of the present invention. The streaming server communicates with a Wifi point 7 managing a local Wifi network. The set formed by the streaming server 3 and the access point Media 7 is designated by "Media Server" or "MS" abbreviated, it being understood that the set can be embodied by a single device, or by two devices independent and connected to each other.

According to an alternative embodiment, the streams of chunks generated by the HLS encoder are transmitted by an HTTP server through a 3G / 4G network, ie a mobile telephone network, to be received by an access point. Wireless.

Whatever its type, the streaming server 3 unencapsulates the chunk received from the different streams, distributes them to reconstitute the services if necessary (when the broadcast data stream includes several multiplexed services) and stores them in a circular buffer memory 6. This circular buffer organized in FiFo ("First In First Out") permanently contains a certain amount of chunks per service which corresponds to a fixed period of reproduction of these services, for example one hour. In this way, if each chunk of a service allows the reproduction of 20 seconds of contents, the buffer allowing a reproduction of one hour of this service contains 180 chunks.

At the local level, the MS communicates with terminals such as smartphones 8 (or "smartphones" according to English terminology), computers 8a portable or not, 8 ter tablets, ... Each terminal (designated by the continued under the generic reference 8) uses the Wifi network managed by the access point 7 to transmit to the streaming server communication requests to receive duly referenced chunks. The communications between terminals are peer-to-peer, which is the French translation of "peer to peer", it is the Anglo-Saxon term that will be used later. Peer to peer communications are managed by the layer of Wifi communication without going through the streaming server 3.

When the MS receives a request from a terminal 8 specifying the IP address of the streaming server, the Wifi communication layer transmits the request to the streaming server. If the request is to receive chunks from a service currently broadcast, then the broadcast service management application searches in memory 6 the chunks requested by this terminal and transmits it through the Wifi point 7.

After having detailed the main elements of the system, we will now explain how these co-operate.

When reproducing audio and / or video content, the terminals 8 requests bursts of three consecutive chunks (this figure being given as an example), and at the beginning of the reproduction of the third, asks for the following three chunks . If a small number of terminals interact via the Wi-Fi network with the streaming server 3, then the latter can manage requests and respond to their requests. In some cases, the number of terminals 8 is important and the resources of the streaming server 3 are insufficient to extract the chunks requested memory 6. This case occurs especially when the MS is placed in a vehicle occupied by many users of terminals 8, whether this vehicle is moving or not, or in a waiting room or show room.

The present invention makes it possible in particular to reduce the workload of the streaming server 3 by transferring a portion to the level of the terminals 8.

Fig. 2 shows an example of a flow chart showing the steps of implementation of the invention according to an exemplary embodiment. According to a preliminary step, the streaming server 3 and the terminals 8 download their broadcast service management applications, the downloading is carried out from a remote site, or from a hardware medium (USB key, smart card, CD, ...).

In step 2.1, the streaming server 3 receives from the broadcast network at least one service. The broadcast service management application then stores the chunks services in the memory 6 managed circularly, and updates a first table listing the services received from the broadcast network. If the function allowing to go back in the content is not available, only the last three chunks can be memorized, ie a duration of the order of 60 seconds. If the rollback function is provided, then the streaming server manager can significantly increase the number of chunks in the circularly managed memory 6 to extend the available time of the audio and / or video contents. At any time, terminals 8 can interrogate the streaming server 3 via the Wifi network and its access point 7, and ask for a list of services currently available. The streaming server returns the list extracted from the first table (step 2.2).

In step 2.3, the user of the terminal TA requests the streaming server to receive the service SI which carries the audio and / or video content Cl. The management application of the broadcast services verifies that the requested service is broadcast and that the corresponding chunks are present in the memory 6. If this is the case, the streaming server extracts from the memory 6 the last chunks of the requested service and requests the Wifi point to transmit them to TA (step 2.4) . The streaming server updates the table indicating that the SI chunks are currently being transmitted to TA. At a later step 2.5, a second terminal TB requests the streaming server to receive the same service SI. The streaming server consults the service configuration table, and notes that this service is already transmitted to the TA terminal. In step 2.6, the streaming server 3 then transmits to the terminal TB not the last chunks of the requested service but the terminal identifier TA, for example its IP_A address.

By receiving this identifier, the terminal TB requests the Wifi point 7 to establish a Peer-to-Peer connection Wifi with the terminal TA identified by the IP_A address and sends a request for receipt of the SI service. Already receiving the chunks of this service and storing them temporarily in its memory, the terminal TA responds to the terminal TB in step 2.7 by a message Peer to Peer indicating that he has the last elements of this service by specifying the numbers of chunks stored in his memory. On receipt of the message, the terminal TB requests to receive a salvo of three chunks, preferably the last three received and stored by the terminal TA (step 2.8). The terminal TA then sends it to step 2.9.

Peer-to-peer exchanges between TA and TB are carried out through the Wifi point and without passing through the streaming server 3. The service chunks to the terminal TB pass through the terminal TA. In this way, the streaming server 3 ensures the supply of the chunks to a first terminal, but this terminal ensures the provision to the next terminal which reduces the workload to be executed by the streaming server. Of course, the solution is generalized by creating a real chain where a second terminal called "current" receives from a first terminal said "previous" the chunks and transmits to a third terminal said "next" who requests it.

Some terminals 8 do not have the resources to manage the retransmission of a service to another terminal in Peer to Peer, or have simply not downloaded their management application broadcast services. According to an improvement, during the request to receive a service, such a terminal signals this fact to the streaming server 3 which records it in the table by associating it with this information. The streaming server does not select to retransmit a service a terminal that does not have the resources to perform such retransmission.

The present invention also covers the fact that a terminal can receive several services at the same time, and that it can therefore transmit the chunks of services received on request from possibly different terminals. This management is possible provided that the resources of the terminal allow it.

According to another embodiment, in step 2.6, the streaming server transmits to the requesting terminal of a service several identifiers terminals. Peer-to-Peer connections are then established between the requesting terminal and the terminals identified by the streaming server. In this way, to receive a salvo of several chunks, a terminal requests a chunk (n) to a first terminal, the next chunk (n + 1) to a second and the next chunk (n + 2) to a third.

After a while, real chains of terminals are formed to broadcast the services within the Wifi network. At any time, a terminal in the chain can interrupt the reception of the chunks, either by cutting the reception, or by withdrawing from the Wifi coverage, or by turning off the device. The chain that is cut off must immediately re-form to continue transmitting the service to the chain terminals after the break.

Fig. 3 represents a local area network comprising a streaming server 3 and five terminals TA, TB, TC, TD and TD communicating with a Wifi point (not shown). Fig. 3 shows the data paths at a specific instant, where the server-side streaming application manages the transmission of the chunks of two services: the service SI to the terminal TA, and the service S2 to the terminal TE. TB receives via the Wifi point the chunks of the SI service transmitted by TA. To avoid burdening the figure, a single arrow TA to TB is represented when in fact the link between TA and TB passes through the access point Wifi 7. TC receives from TB the chunks of the service SI and TD receives from TC the SI service chunks. The table listing the services received from the broadcast network indicates that SI is transmitted to TA and that S2 is transmitted to TE.

Suppose now that the user of the terminal TC decides to no longer receive the service SI but the service S2. TC transmits a request to the streaming server 3 to receive this service and the broadcast service management application responds to it by indicating to transmit its request to TE. As described in FIG. 2, TC requests TE through a Peer to Peer link via the Wifi point to receive the chunks of the S2 service, and TC becomes the second terminal of the transmission chain of the S2 service. TC no longer asks to receive the SI chunks from TB, and no longer has them in memory. When TD asks TC to send him SI chunks, TC either does not answer him, or responds that he does not have them. TD then speaks to the streaming server 3 to request to receive SI. When reading the table, the streaming server responds to contact TA. TA acknowledges that its distributed service management application is already busy transmitting SI chunks to TB, and responds to TD to address TB. TD transmits its request to TB. TB finding that he is the last in the chain, responds that he has the last chunks of this service and he is ready to transmit. Thus, the situation illustrated in FIG. 4 intervenes quickly where two channels are operational, one to transmit SI from the streaming server 3 to TA, then to TB, then to TD, and another to transmit S2 from the streaming server 3 to TE, then to TC.

It can be seen that this dynamic management adapts well to the modification of the needs of the terminals in terms of reception of services.

According to one variant, the management of the terminal chains is carried out entirely at the level of the application for managing the services broadcast, this application being resident in the streaming server which thus has the total knowledge of the flows between terminals of the Wi-Fi network and the composition of the various current channels.

The passage from one terminal to another to convey the chunks causes a delay in the reception by the terminal at the end of the chain and therefore its reproduction. According to an improvement, the broadcast service management applications resident in the streaming server 3 and the terminals 8 limit the number of terminals forming a transmission chain of the audio and / or video contents. If a terminal finds that its sequence number in the chain exceeds the maximum number, for example, then it indicates this information to the streaming server. The streaming server records the fact that this channel is complete and knows that it must no longer provide connections to this service through this terminal, at least over a period of time. The streaming server transmits to the requesting terminal, either the identifier of another terminal to which it transmits the chunks of this service, or its own identifier indicating in this that assumes the management of this terminal and thus creates a new channel.

According to an alternative embodiment, in step 2.6, the streaming server transmits to a requesting terminal of a service a list of several terminal identifiers to which the streaming server is currently transmitting the requested service and which are therefore first terminals. of chain. The calling terminal is addressed to a first terminal of the list and finds that the maximum number of terminals is reached or that no terminal in the chain has the necessary resources to transmit the service to it, so it decides to pass itself. to another first terminal in the list. If no terminal of the channels thus explored can deliver this service, then the requesting terminal transmits to the streaming server a request to create a new channel in which it is the first terminal.

Fig. 5 shows an example of a table listing the services received from the broadcast network, this table is updated by the management application of the broadcast services present in the streaming server 3. The example presented shows four services broadcast and received by the streaming server. A first service called "Weather Info" is transmitted to the terminal T1 having the IP address "IP_1". A second service called "Channel 1" is transmitted to the terminal T5 and terminal T18. The table indicates that the chain that starts with the T5 terminal has reached its maximum number of terminals. If a terminal requests to receive this service, then the streaming server responds by transmitting the IP_18 address of the terminal T18. A third service called "Channel 2" is not transmitted to any terminal. A fourth service called "traffic information" is transmitted to terminals T3, T18 and T1. The terminal T3 is marked as not connectable because it does not have the resources necessary to support the transmission of chunks to another terminal. Terminal T18 is also marked as non-connectable because, already receiving the second service and retransmitting it to another terminal, it no longer has the resources to support the transmission of chunks to other terminals. If a terminal requests to receive this fourth service, then the streaming server transmits the Tl address. Note that Tl also receives the first service. Looking at the table, we can see that Tl has the resources to manage two service transmission chains.

The invention is not limited to the embodiments that have just been described. In particular, any computer device interacting with a server via a Wi-Fi connection is capable of implementing the present invention.

Claims

A method of transmitting at least one audio and / or linear video content from a broadcast server (3) to a plurality of terminals (8) using a Wifi network, comprising a prior step of receiving (2.1) said content by the broadcast server using a broadcast network and a broadcast step (2.4) by the broadcast server to a first terminal, said content in the form of a stream of data packets, the method comprising a step of transmitting (2.5) by a second terminal of a request to the broadcast server to receive, by the Wifi network, the same content, said step of transmitting said request triggering a transmission step (2.6 ) by the broadcast server of a message identifying the first terminal as the transmitting terminal of this content, the second terminal then sending a request to receive (2.8) this content to the first terminal to receive said content through an even link topeer, characterized in that it further comprises the following steps:

sending by a requesting terminal of a content to a so-called "previous" terminal of a request to receive this content by a peer-to-peer link,

transmission by the previous terminal in response to said request for a message to the requesting terminal indicating to request this content to a so-called "next" terminal, the previous terminal already transmitting this content to the next terminal,

reiteration of the two preceding steps, the next terminal becoming the previous terminal, until a subsequent terminal transmits said content to the requesting terminal

counting the iterations by the broadcast server, the following steps being triggered when the number of iterations reaches a determined maximum value:

o stop iterations, o search by the broadcast server of another first terminal receiving the content by the server,

o sending by the requesting terminal a request to receive this content to the other first terminal to transmit said content.

2. A method of transmitting content according to claim 1 characterized in that it comprises a step of managing a list at the broadcast server (3), said list associating a given content with at least one identifier of a terminal (8) which receives from the broadcast server this content, and in that the step of transmitting a message, by the broadcast server, in response to a request sent by the second terminal to receive this content, comprises a substep of selection by the broadcast server, in said list, of an identifier of a terminal which is associated with the requested content and a substep of transmission, in said message, of said selected identifier, to the second terminal .

3. A method of transmitting content according to claim 2 characterized in that it comprises a step of transmitting a message from a terminal (8) to the broadcast server (3) indicating that the terminal has not the resources necessary to transmit to another terminal the content currently received and associated in the list, this information being introduced into the list managed by the broadcast server, such a terminal not being selected by the broadcast server to transmit the content to another terminal.

4. A method of transmitting content according to claim 2 or 3 characterized in that it comprises a step of transmitting a message from a terminal (8) to the broadcast server (3) indicating that the terminal has the resources necessary to transmit to a different terminal a plurality of content currently received and associated in the list, this information being introduced in the list managed by the broadcast server, such a terminal being selected by the broadcast server to transmit one of the contents to another terminal.

A method of transmitting a content according to any one of the preceding claims; characterized in that the message transmitted by the broadcast server in response to a request to receive a content by the Wi-Fi network comprises a list of several terminals identified as terminals receiving said content, the requesting terminal of this content addressing a first terminal of the list to receive this content and exploring a succession of terminals from this first terminal of the list by peer-to-peer links, a new request for reception of this content to another first terminal of the list being triggered by the requesting terminal when the number of iterations reaches a maximum value determined without being able to receive this content.

A method of transmitting a content according to claim 5; characterized in that the requesting terminal issues a request to receive the requested content directly from the broadcast server when no terminal of the terminal successions starting with the first terminals of the list transmitted in the message is available to transmit the requested content. .

7. Terminal (8) called "requestor" intended to receive at least one linear audio and / or video content originating from a broadcast network, said terminal including at least one data storage memory of the content and a means of communication via Wifi for transmitting and receiving messages through a Wifi point (7), said communication means transmitting to a broadcast server a request for receiving said content in the form of a stream of data packets, said means of communication receiving in response said data packets, said packets being stored in the data memory, said means subsequently receiving a request from another terminal (8) for transmitting to said other terminal said previously stored data packets in said memory means transmitting in response said packets extracted from the data memory;

characterized in that the means of communication transmits to a so-called "previous" terminal a request to receive a content according to a peer-to-peer link, this content being already received by the preceding terminal, the communication means receiving from this previous terminal in response to said request a message indicating to request this content to a terminal called "next", the previous terminal already transmitting this content to the next terminal,

the requesting terminal reiterating the requests to each subsequent terminal, the next terminal becoming the preceding terminal, until a subsequent terminal transmits said content to the requesting terminal, the requesting terminal counting iterations and when the number of iterations reaches a determined maximum value triggering the following operations: stopping requests to the previous terminals,

sending to a broadcast server a request to receive the identity of another terminal receiving the content directly by this server,

sending by the requesting terminal a request to receive this content to this other terminal to transmit said content.

8. Computer program product downloadable from a communications network and / or stored on a computer-readable medium and / or executable by a central unit, characterized in that it comprises program instructions for the implementation of at least one step of the method of transmitting a content according to any one of claims 1 to 6.