WO2013135976A1

WO2013135976A1 - Method of teletransmission of a data set from a sender device destined for at least one destination device, associated sender device and destination device

Info

Publication number: WO2013135976A1
Application number: PCT/FR2012/050531
Authority: WO
Inventors: Thierry Lelegard
Original assignee: Logiways France
Priority date: 2012-03-14
Filing date: 2012-03-14
Publication date: 2013-09-19

Abstract

Method of teletransmission of a data set from a sender device (2) destined for at least one destination device (4), comprising the following steps: • a step of constructing a stream to be teletransmitted (FD VoDl) comprising the data set; • a step of teletransmission of the stream thus constructed destined for at least the destination device; • at least one information element (30) is introduced into the stream to be teletransmitted, indicating a size of a part of the set of data present in the stream to be teletransmitted upstream of the information element and/or a size of a part of the set of the data present in the stream to be teletransmitted downstream of the information element.

Description

Method for teletransmission of a data set from a transmitting device to at least one destination device, associated sending and receiving devices. The present invention relates to a method for teletransmission of a data set from a transmitting device to at least one destination device, comprising the following steps:

a step of constituting a stream to be transmitted,

a step of teletransmission of the stream thus constituted to at least the destination device.

Such a transmission method is for example implemented in video-on-demand services.

There are three types of video-on-demand (VoD) services.

Demand ") implemented between a broadcast server and a decoder associated with a TV screen, which receives a video broadcast from the broadcast server over a broadcast network, for example wireless.

In the "live" video on demand service, the user selects content and watches the content while his set-top box receives it from a remote service provider server. This is a streaming broadcast to a particular user who has selected that content. The user can select "pause" type instructions,

"Stop", "go back", "review from the beginning", "jump forward" etc. Each of these instructions is transmitted to the server, which adapts in real time the broadcast content according to the transmitted instructions. For this type of VoD, it is necessary to have very broadband networks with a return channel, with very low latencies to provide a good quality service.

In the "Pull VoD" type VoD service, the user selects a content, buys it and requires a download of the selected content from a remote server provider. Once downloaded by the decoder, the content is stored locally at the decoder, before being viewed. For this type of VoD, it is necessary to have broadband networks with a return channel and the decoder must have a storage memory of the downloaded content.

In the "Push" type VoD service, an operator performs a selection of contents and "pushes" all of these contents via a broadcast network to all the decoders, in which the contents are then saved. At any moment, the user can choose one of the contents and watch it, provided that he is entitled, for example if has purchased a subscription giving access to this selected content, or provided that he buys it beforehand. A conventional unidirectional broadcast network can be used and current technologies allow decoders to have large storage capacities.

However, in current VoD "push" systems, it is difficult to locate and effectively correct missing data in a broadcast stream received by a decoder.

For this purpose, according to a first aspect, the subject of the invention is a teletransmission method of the aforementioned type, characterized in that the step of constituting a stream to be transmitted further comprises the steps according to which:

at least one piece of information is introduced into the stream to be transmitted, indicating a size of a part of the set of data present in the stream to be transmitted upstream of the piece of information and / or a size of part of the set of data present in the stream to be transmitted downstream of the information element.

In embodiments, the remote transmission method according to the invention further comprises one or more of the following features:

an information element indicating a size of the data of all the data present in the stream to be transmitted upstream of the information element and / or a size of the data of all the data present in the stream to teletransmitting downstream of the information element is inserted into the stream;

the information element further comprises an identifier of the data set;

elements of information are introduced into the stream to be transmitted, at regular or non-regular intervals, each piece of information indicating a size of a part of the set of data present in the stream to be transmitted upstream of the an information element and / or a size of a portion of the set of data present in the stream to be transmitted downstream of the information element;

a destination device is a set-top box;

the data set comprises metadata and / or audio and / or video services of a TV service in "push" mode;

- the information element indicates a number of next retransmission (s) of the data set;

the method comprising the following steps implemented by the recipient device:

- reception of the telepransmitted stream; detecting the start of a set of data in the telecontrol stream and storing the segments of said set of teletransmitted data;

the recipient device identifies, based on the segments of the set of data received and at least one size indicated in said information element, that data from the data set have not been received, and identifies in addition according to at least said indicated size, at least one segment, of said set of teletransmitted data, in which data are missing;

after reception of a retransmission of the data set of a stream to be transmitted comprising said set of data, the recipient device stores, the, or the segment (s) of said set of data identified (s) during previous teletransmission as segments in which data is missing;

the destination device determines a data set corrected according to the segments recorded for said set of data during a previous remote transmission and segment (s) recorded during the retransmission.

According to a second aspect, the subject of the invention is a device for teletransmission of a set of data destined for at least one recipient device, adapted to constitute an upload stream comprising the set of data and for teletransmitting said stream as well. constituted to at least the destination device; said device being characterized in that during the constitution of a stream to be transmitted, it is adapted to determine at least one piece of information indicating a size of a part of the set of data present in the stream to be transmitted by teletransmitting. upstream of the information element and / or a size of a part of the set of data present in the stream to be transmitted downstream of the information element and introduce at least said information element into the stream to teletransmit.

According to a third aspect, the subject of the invention is a device for processing a set of data, adapted to receive by remote transmission a stream comprising the set of data, said processing device being adapted to memorize at least a part of said set teletransmitted data device, said processing device being characterized, in that it is adapted to detect at least one piece of information introduced in the stream to be transmitted, indicating a size of a part of the set of data present in the stream to be transmitted upstream of the information element and / or a size of a part of the set of data present in the stream transmitted downstream of the information element and in that it is adapted for processing said data set according to at least said detected information element. Such a device makes it possible to identify and complete the missing portions of the stream transmitted during a first broadcast.

According to a fourth aspect, the subject of the invention is a data stream adapted to be transmitted between a transmitting device and a receiving device, comprising a set of data, characterized in that it comprises at least one piece of information indicating a size of a part of the data set present in the stream, upstream of the information element and / or a size of a part of the set of data present in the stream and downstream of the information element.

The invention will be better understood on reading the description which follows and on examining the figures which accompany it. These figures are given for illustrative purposes but in no way limitative of the invention. These figures are as follows:

FIG. 1 is a view of a system in one embodiment of the invention;

FIG. 2 is a graph showing the use of the bandwidth of a broadcast channel as a function of time for a VoD Push broadcast service in one embodiment of the invention;

FIG. 3 represents the structure of a VoD broadcast file in one embodiment of the invention;

FIG. 4 is a flowchart of steps implemented in one embodiment of the invention;

FIG. 5 is a flowchart of steps implemented in one embodiment of the invention.

According to the invention, upstream of the broadcast, the original data of the contents (audio, video, ...) are analyzed, then they are multiplexed with other information (metadata, posters, images, etc.). And packet counters of each of the components of the VoD unit thus constituted (audio / video contents and / or metadata, etc.) are inserted at regular intervals or not, as is detailed hereinafter.

A video-on-demand system 1 offering a VoD service of the Push type, hereinafter referred to as "Push VoD service", generally involves a large number of actors, among whom:

audiovisual content providers and metadata providers associated with each of these audiovisual contents,

a technical operator who prepares, using each content and associated metadata, a VoD unit, which codes all the VoD units and prepares a corresponding broadcast file or TS file ("Transport Stream") comprising this VoD unit, the broadcasting operator who is in charge of creating the global transport stream, possibly comprising several TS files, possibly multiplexed, and furthermore performing the broadcasting of the resulting TS stream, intended for users who own decoders.

With reference to FIG. 1, the video push system 1 is considered in a simplified representation, in which a server 2 is adapted to constitute the video elements on demand and to broadcast them via a teletransmission channel. a broadcast network 3, in the form of a transport stream comprising VoD broadcast files and where appropriate, further comprising current TV broadcast programs, to user decoders 4.

The broadcast network 3 may be, for example, a digital television broadcasting network, terrestrial (wireless or wired) or satellite type MPEG or DVB (in English "Digital Video Broadcasting"). In this case, the broadcast network 3 is a digital terrestrial broadcasting network.

In the embodiment of the invention described, a VoD unit - outside the VoD units containing only metadata and not containing an image or audio / video or playlist - comprises an element defining a content directly or indirectly, eg a film, a documentary etc.

A VoD unit comprises several distinct types of data, described below. A VoD unit first comprises a VoD unit identifier, for example a 32-bit number, which defines it uniquely.

A VoD unit includes, besides its identifier,

a dynamic content that can be read (ie restored) by a decoder 4 on a screen associated with it, comprising:

o an audio / video sequence, or

a playlist, including an ordered list of identifiers of other VoD units;

a static content, which can be displayed at least partially by a decoder on an associated screen, comprising:

o an image or a set of images, and / or

o a set of metadata.

In one embodiment, the dynamic content comprises one and only one audio / video sequence, or a playlist, but not both, so that the playback command of the VoD unit received by a decoder from, for example, 'a remote control, is unambiguous. An audio / video sequence includes a video track and / or any number of audio tracks and subtitles.

A VoD unit may not contain dynamic content, but only static content with an image of wallpaper or advertising image, which may for example be used as a background image to display menus on the screen.

A VoD unit may not have dynamic content or image.

The VoD unit necessarily has a set of metadata. The only element needed in the metadata of the VoD unit is the VoD unit identifier. In one embodiment, a VOD unit identifier is unmodifiable.

Some of the metadata are of an informational nature, for displaying this metadata by the decoder 4 on the screen. Other metadata have a technical impact on the life of the VoD unit and are used by the decoder to drive its operation of the VoD unit.

Metadata can be classified into several categories and subcategories and can include:

Editorial information about the content: title, description, actors, producer, production date, chapters ...

Classification information, for example according to local laws: parental control, minimum age, content classification ...

- Commercial information: purchase price of the VoD unit, link to commercial lots of which the VoD element is part ...

Technical informations :

o "visible" or "hidden" character (depending on the character indicated, the decoder will make the VoD unit explicitly visible and selectable in the decoder menus intended for the user, or not;

VoD "hidden" are objects referenced elsewhere that are not selected directly by the user: simple images, advertising banner etc.);

o playing time, audio / video format;

o deletion date (the decoder will delete the VoD unit at a specific time according to this date);

o identification of the content provider;

o dates and count of VoD transmissions to the decoder, minimum accepted download quality.

- References to other VoD units (for example when the current VoD unit is the trailer of one or more VoD units). - Access control: identification of the type of subscription required if necessary, or indication that a separate purchase is necessary; additional technical access criteria.

- Control of use:

o Time window allowed for purchase or selection of the VoD unit

(the decoder 4 is adapted to allow the purchase or selection of this unit only during this time window);

o Maximum duration of provision of the VoD unit for reading, and / or maximum number of readings allowed (the decoder 4 is adapted to stop the provision of the unit in the menus and / or screen areas if these maximum thresholds are exceeded),

o Expiration date (the decoder 4 is adapted to stop the provision of the unit in the menus and / or screen areas if the expiration date is exceeded).

The server 2 comprises a memory 9 and a processor 10.

The memory 9 is adapted on the one hand to store the data corresponding to the VoD units and on the other hand to store a computer program P1.

The computer program P1 includes software instructions adapted to implement the steps described below with reference to FIG. 4 when they are executed by the processor 10.

Thus, in the context of constituting the portion of a TS stream corresponding to a VoD unit, here a unit named VoD1, the server 2 performs the steps indicated below.

In a step 100, the various data constituting the unit VoD1 are optionally encrypted, then they are distributed in TS packets ordered according to the DVB standard, for example the first packets correspond to the metadata, and the last packets corresponding to the dynamic data or images for example. The unit VoD1 thus corresponds to an ordered chain of N packets TS.

A type field in each packet indicates the type of data present in the packet (eg an "X" value in the type field indicates metadata, an "X + 1" value indicates audio, a "X" value +2 "indicates video, an" X + 3 "value indicates subtitles, etc.).

In a step 101, with reference to FIG. 3, a start primer 10 comprising specific packets 20, 21, 22, 23, 24, of the "sequencing" type, also called DMT type (for "Download Marker Table"), is added before packets from the VoD unit. On the other hand, an end leader 12 also including DMT specific packets 40, 41, 42, 43, 44 is after the packets of the VoD unit.

A DMT packet consists of the following data fields:

a field A _DM T indicating the identifier of the unit VoD considered, here the unit VoD1;

a B _DM T field indicating a remaining number of future reruns of the VoD1 unit as part of the VoD Push service;

a field C _DM T indicating the number of packets of the unit VoD considered, here the unit VoD1, which are situated between the beginning of the ordered chain of the packets of the unit VoD, and the packet DMT considered;

a D _DMT field indicating the total number of packets of the ordered string of packets of the VoD unit.

Thus, in the case considered, each DMT file 20-24 from the start primer 10 to the zero value indicated in the field C _DM T- Each DMT file 40-44 of the end primer 12 to the value N indicated in the field C _DM T- Each DMT file 20-24 and 40-44 of the start primers 10 and end 12 at the value N indicated in the _DMT field.

In a step 102, DMT packets 30, 31, 32, 33, 34, 35 are further inserted at various locations of the ordered string of data packets obtained from the VoD unit. The number of these DMT packets, here of 6, can actually take varied values.

In one embodiment, such a DMT packet is inserted all n data packets of the VoD unit (eg n = 1000).

The portion of flow between 2 DMT (information elements) implicitly constitutes a segment of the flow.

The D _DM T field of each DMT 30-35 packet indicates N. The A _DM T field of each DMT 30-35 packet indicates the identifier of the VoD1 unit.

In this case, the DMT packet 30 is inserted between the segments 11a and 11b of data packets of the VoD1 unit. The DMT field C _DM T 30 indicates the number of packets present in the segment 1 1 a.

The DMT packet 31 is inserted between the segments 11b and 11c of data packets of the VoD1 unit. The DMT field C _DM T 31 indicates the number of packets present in the segments 1 1 a and 1 1 b.

The DMT packet 32 is inserted between the segments 1 1 c and 1 d of data packets of the unit VoD1. The DMT field C _DM of the DMT packet 32 indicates the number of packets present in the segments 1 1a, 1 1b and 1 1c. The packet DMT 33 is inserted between the segments 1 1 d, 1 1 e of data packets of the unit VoD1. The C _D MT field of the DMT packet 33 indicates the number of packets present in the segments 1 1a, 1 1b, 1 1c and 1 1d.

The packet DMT 34 is inserted between the segments 1 1 e, 1 1 f of data packets of the unit VoD1. The C _D MT field of the DMT packet 34 indicates the number of packets present in the segments 1 1 a, 1 1 b, 1 1 c, 1 1 d and 1 1 e.

The packet DMT 35 is inserted between the segments 1 1 f, 1 1 g of data packets of the unit VoD1. The DMT _DM field DMT 35 indicates the number of packets present in the segments 1 1a, 1 1b, 1 1c, 1 1d, 1 1e and 1 1f.

The FD VoD1 broadcast file thus determined for the unit VoD1 comprises the start 10 and end 12 primers, the set 11 comprising the packet segments of the VoD unit separated by the DMT packets 30-35.

In a step 103, the server broadcasts the broadcast file FD VoD1 in the stream TS on the remote transmission channel of the broadcast network 3, to the decoders 4.

The information indicated in the data fields of the DMT packets is previously prepared by the server 2. In particular, the remaining number of future repeats indicated in the field B is decremented before each rebroadcast of the VoD unit.

The location of the DMT files is preferably kept unchanged between the different broadcast operations of the same unit VoD.

The VoD broadcast file of a VoD unit containing audio / video is large, typically several gigabytes. The broadcast file of a VoD unit containing only metadata is typically a few megabytes.

For example, each transport packet has a size of 188 bytes.

The VoD Push broadcast service in the form of a broadcast stream comprising VoD broadcast files can be permanently active, or during specified time windows or according to the bandwidth currently available on the broadcast network 3.

A graph having the abscissa time and ordered the bandwidth of the broadcast channel used by the VoD Push service is shown in Figure 2, illustrating a VoD Push broadcast service in an embodiment of the present invention.

Thus during a day (24 hours), a PMT (Program Map Table) broadcast file is broadcast continuously on the broadcast channel. This PMT message has respective data fields A _PMT and B _PMT . The _PMT data field identifies the proposed VoD push service. The data field Β _ΡΜ τ defines the window time T _VO D during which VoD units of the VoD Push service will be broadcast.

In one embodiment, the data field Β _ΡΜ τ further identifies the time windows for broadcasting the service over the next few days.

During this time window, VoD broadcast files are broadcast: in this case the FD VoD1 file considered above comprising for example a film "Movie 1", the VoD2 file corresponding to a second unit VoD, for example the promotional advertisement of the film "Film 1", followed by a VoD3 file including for example an audio / video advertising sequence.

The decoders 4 each comprise a data storage hard disk 5, a microprocessor 6 and a smart card 7. They are adapted to monitor the remote transmission channel, to receive the TS stream, to extract the data from the VoD units from the data files. VoD broadcast received in the TS stream, storing the VoD units on the hard disk 5, and subsequently processing them so as to render viewable on a display screen information relating to audio / video contents present in the VoD units and / or the contents themselves.

The display screen is for example a television screen connected to the decoder 4.

In the embodiment considered, the hard disk 5 is adapted on the one hand to store the data corresponding to the VoD units and on the other hand to store a computer program P2.

The computer program P2 comprises software instructions adapted to implement the steps described below with reference to FIG. 5 when they are executed by the microprocessor 6.

In a step 200, implemented on a regular basis, in particular when the decoder 4 is not downloading a VoD unit on its hard disk 5, the decoder 4 scans the teletransmission channel to detect, in the stream TS that it receives a PMT file relating to the VoD Push service, based on the information present in the data field A _PMT of the PMT file

When the decoder 4 detects such a PMT file, according to the time window T _VO D, the decoder 4 puts to sleep its scan function of the broadcast channel until the beginning of the time window indicated in the data field B _PMT PMT file.

In a step 201, for example implemented from the beginning of the indicated time window, the decoder 4 scans the teletransmission channel in order to detect the presence of DMT packets in the TS stream received. When the decoder 4 detects a DMT packet from a start start of a broadcast file of a VoD unit (DMT packet with the null value in the C _D MT field) OR a DMT packet whose B _DM T field indicates a non-zero number of future rebroadcasts of the VoD unit considered, or when the identifier of the VoD unit considered is in a list L2 of the hard disk 5, in a step 202, the decoder 4 stores in the disk hard 5, in association with the identifier of the considered VoD unit, for example the VoD1 unit, the set of broadcast file packets that follow the detected DMT packet, in the order in which they are received.

The detection with the value in the field D _DMT equal to the value in the field CDMT (ie of a DMT packet of the end primer) signals to the decoder 4 the end of the broadcast file of the unit VoD1 considered.

Another broadcast file corresponding to another Vod unit may follow this first file and the processing operated by the decoder 4 is then similar to that described above.

The identification by the decoder 4 of the value of the field C _DM T of a DMT file commonly received during the download enables it, using the values provided in the fields C _D MT and D _DM T, to determine an index of download progress of the VoD1 unit.

In one embodiment of the invention, in a step 203, which can be consecutive to the end of the recording of data packets of the VoD1 unit or which can take place in parallel with this recording, the decoder 4 is adapted to determine missing or defective packets, as well as their location relative to DMT packets.

The decoder 4 initializes in the hard disk 5 an LVOD1 list for each operation of downloading a broadcast file of a VoD unit, here the unit VoD1.

It successively identifies each DMT packet relating to the registered or currently recorded VoD1 unit, it compares the number of packets actually received upstream of the DMT packet identified for the VoD1 unit (outside the DMT files) and recorded by it in the hard disk 5, with the number indicated in the field C _DM T of the identified DMT packet. When the two numbers are equal, no missing packet is deplored in the segments of the VOD unit upstream of the DMT packet considered. It updates the L _VO DI list by adding a pair of data, whose first term is the number indicated in the C _DM T field of the new detected DMT file and the second term is 0.

When the two numbers are not equal, the decoder 4 updates the list

LVODI, adding a couple of data, whose first term is the specified number in the C _D MT field of the new detected DMT file and the second term is the number of missing packets (result of the difference between the number indicated in the C _D MT field of the identified DMT packet and the number of packets actually received until then for the VoD1 unit, except DMT packets).

The list L _V ODI therefore comprises a sequence of pairs, which is considered hereinafter in increasing order of the values of their first term (field C _D MT) -

Based on this L _VO DI list, the decoder 4 determines the location of missing packets (s) with respect to the DMT packets it has received in the VoD1 broadcast file.

The decoder 4 identifies the presence of missing packets when it detects two successive pairs in the list L _VO DI ordinate, whose values of the second terms differ between it. If one names CMT, the value of the first term indicated by the first, in the list L _VO DI, of these two couples including and CMT _{i + 1} the value of the first term indicated by the second in list L _VO DI of these two pairs, the decoder 4 detects missing packets in the data from the VoD unit located between the two DMT packets having respectively as value CMT, and CMT _{i + 1} in their C T _DM _field. These two DMT packets are called terminal DMT packets. They are the terminals of a failure interval. The number of packets that are missing between these two packets is equal to the difference between the value of the second term of the second of the two pairs and that of the second term of the first of the two pairs.

In one embodiment, the decoder 4 further detects packets or packet sequences of the broadcast file of the VoD unit for which the quality is degraded (high error rate) and determines the two closest DMT packets, which will be called terminal DMT packets) between which each of these packets or packet sequences appear, in order to download or process only the packets between these two DMT packets. These two terminal DMT packets are the terminals of a failure interval.

The decoder 4 performs one or more treatments depending on the location of missing packets.

In one embodiment, when for a given VoD unit, the decoder 4 has identified missing or insufficient quality packets, that these packets have been located between two given terminal DMT packets as indicated above, the decoder 4 is adapted to evaluate the quality of the stored VoD unit, based on the amount of missing or low quality data and their distribution in the known broadcast file chain through DMT fault terminal packets. The decoder 4 can then decide to delete the VoD unit when the quality of the VoD unit is below a determined threshold. For example, if the download quality evaluated by the decoder is below the threshold of the minimum download quality indicated in FIG. the metadata of a VoD unit, then the VoD unit is considered unavailable by the decoder.

Decoder 4 otherwise decides to wait for a next broadcast of the VoD unit to complete the VoD unit with at least some of the missing / failed packets before making the VoD unit available for playback to the user of the decoder 4.

The decoder 4 is then adapted to indicate in a list L2, the identifier of the VoD unit considered, as well as the failure intervals defined by the terminal DMT packets, each of these packets being associated with the value indicated in its field. C _DMT -

In one embodiment, the decoder 4 is adapted for a future broadcast of a VoD unit indicated in the list L2, scan the broadcast file being received and do not record the packets broadcast for this purpose. VoD unit between the two DMTs packets of each failure interval associated in the L2 list with the identifier of the considered VoD unit.

Once the decoder 4 has stored the newly received data packets in the hard disk for each failure interval, it can complete the stored initial broadcast file by replacing, in this initial file, the packets of each failure interval. by the corresponding newly recorded packets following the replay, or by combining in each failure interval the original and newly registered file packets.

The metadata are stored in plain text in a database on the hard disk 5, in correspondence with an identifier of the VoD unit to which they belong. In some cases, an audio, video or image type content, present in a VoD unit is stored in encrypted form under the hard disk and can not be "read", ie decrypted, and then restored on the screen, only if was purchased by the user of the decoder 4.

It should be noted that some of the audio, video or image contents present in a VoD unit are not in encrypted form and are freely accessible to the user, for example, content relating to movie trailers, movie posters, films and videos. images or audio / video of commercials ...

The purchase can be made in different ways, for example by subscription, and / or online and / or offline transaction. Once the purchase has been made, the decoder 4 receives an authorization which it stores on the smart card 7 and which makes it possible to implement decryption by the decoder.

The decoder 4 is adapted to determine, according to the metadata of the VoD units, menus offering contents of the available VoD units stored in the hard disk 5 following the broadcast in "push" mode, and to display these menus on a connected screen. to the decoder.

On a display screen may appear menus for example organized by themes (movies, documentaries, children, sports etc.), proposing user-purchasable content, and also areas on which, automatically, without selection of the user, audio / video contents are read and / or images are displayed: for example, trailers, advertisements, movie posters ...

The decoder 4 is further adapted to read / display on the screen content present or referenced in the VoD unit corresponding to the selection of the user in a menu (and after verification by the decoder access rights, including in particular the verification on the smart card 7 of the corresponding authorization relating to the user).

In one embodiment, the decoder 4 for a "visible" VoD unit of audio / video type, for example comprising an audio / video sequence (a film) and an image (for example the film poster), is adapted to display in menus the editorial and classification information, as well as the image. Then upon user selection of this VoD unit from this display, it processes the audio / video content of the VoD unit so as to render it on the screen, by means of access control checks and so on.

The decoder 4 is adapted to process the VoD units and to read / display the audiovisual content contained according to the information and constraints stipulated in the metadata of these VoD units.

In one embodiment, the DMT packets present in the broadcast file of a VOD unit are used by the decoder 4 to implement the fast read, or the read hop, of the VoD unit.

The present invention has been described with reference to a Push type VoD service. However, it can be implemented during any type of data transmission.

In one embodiment, other information is indicated in a packet

DMT, in addition to, or instead of, the parameter C _DM T, to indicate the place of the DMT packet with respect to the broadcast file for example, the number of packets between the DMT packet and the end of the broadcast file, or still the number of packets separating the considered DMT packet from the immediately preceding or immediately following DMT packet.

In one embodiment, a DMT packet provides separate packet counters for different data types of the originating unit, for example a counter video data, a counter for each audio track, a counter for subtitles, etc. The decoder is then adapted to perform a rendering of the VoD unit and / or a combination with data of a subsequent rediffusion, further depending on the types of data identified as missing based on the received DMT packets.

According to the invention, depending on the information inserted into the stream, the decoder determines the volume of data that it should have received in each of several segments.

The present invention makes it possible to expell the transmitted stream from any useless data. Notably, the various information not referenced directly by the original signaling is not taken into account for the generation of the output stream, likewise for the different stuffing packets. or so-called "no payload" packets.

Claims

Method for teletransmission of a data set from a transmitting device (2) to at least one destination device (4), comprising the following steps:

a step of constituting a stream to be transmitted (FD VoD1) comprising the data set;

a step of teletransmission of the stream thus constituted destined for at least the recipient device;

said method being characterized in that the step of constituting a stream to be transmitted further comprises the steps according to which:

at least one piece of information (30) is introduced into the stream to be transmitted, indicating a size of a part of all the data present in the stream to be transmitted upstream of the piece of information and / or a size of a part of the set of data present in the stream to be transmitted downstream of the information element.

A teletransmission method according to claim 1, wherein an information element (30) indicating a data size of all the data present in the stream to be transmitted (FD VoD1) upstream of the information element and / or a data size of the set of data present in the stream to be transmitted downstream of the information element, is inserted into the stream.

The remote transmission method according to claim 1 or 2, wherein the information element (30) further comprises an identifier of the data set.

Remote transmission method according to one of the preceding claims, wherein information elements 30, 35) are introduced into the stream to be transmitted, at regular or non-regular intervals, each piece of information indicating a size of a part of all the data present in the stream to be transmitted (FD VoD1) upstream of the information element and / or a size of a part of the set of data present in the stream to be transmitted downstream of the information element. Remote transmission method according to one of the preceding claims, wherein a destination device (4) is a set-top box.

The remote transmission method according to one of the preceding claims, wherein the data set comprises metadata and / or audio and / or video services of a TV service in "push" mode.

The remote transmission method according to one of the preceding claims, wherein the information element (30) indicates a number of next retransmission (s) of the data set.

Teletransmission method according to one of the preceding claims, comprising the following steps implemented by the destination device (4):

- reception of the telepransmitted stream;

detecting the beginning of a data set in the telecontrol stream and storing the segments of said remote data set.

A remote transmission method according to claim 8, wherein the destination device (4) identifies, as a function of the segments (11a, 11g) of the received data set and at least one size indicated in said data element. information, that data from the data set has not been received, and further identifies according to at least said indicated size, at least one segment, of said set of tele-transmitted data, in which data are missing.

A teletransmission method according to claim 9, wherein following reception of a retransmission of the data set of a stream to be transmitted comprising said data set, the recipient device (4) stores, the, or the segment (s) said set of data identified during a previous remote transmission as segments in which data are missing.

A teletransmission method according to claim 10, wherein the destination device (4) determines a corrected data set according to the segments recorded for said data set in a previous remote transmission and segment (s) recorded during the retransmission.

12.- Device for remote transmission (2) of a set of data destined for at least one destination device (4), adapted to constitute a stream for teletransmitting (FD VoD1) comprising the set of data and for teletransmitting said stream thus constituted to at least the destination device;

said device being characterized in that when constituting a stream to be transmitted, it is adapted to determine at least one piece of information (30) indicating a size of a part of the set of data present in the stream teletransmitting upstream of the information element and / or a size of a part of the set of data present in the stream to be transmitted downstream of the information element and introducing at least said information element in the stream to teletransmit.

13.- teletransmission device (2) according to claim 12, wherein an information element (30) introduced indicates a data size of the set of data present in the stream to be transmitted upstream of the element of information and / or data size of all the data present in the stream to be transmitted downstream of the information element.

14. - A remote transmission device (2) according to claim 12 or 13, wherein the information element further comprises an identifier of the data set.

15. - teletransmission device (2) according to one of claims 12 to 14, adapted to introduce information elements in the stream to be transmitted, at regular intervals or non-regular, each piece of information indicating a size of a part of the set of data present in the stream to be transmitted upstream of the information element and / or a size of a part of the set of data present in the stream to be transmitted downstream of the element of information.

16. - Teletransmission device (2) according to one of claims 12 to 15, wherein the dataset comprises metadata and / or audio and / or video services, a TV service in "Push" mode. ".

17.- teletransmission device (2) according to one of claims 12 to 16, wherein the information element indicates a number of next (s) retransmission (s) of the data set.

18. A data set processing device (4) adapted to receive by remote transmission a stream (FD VoD1) comprising the data set, said processing device being adapted to memorize at least a part of said set of data. teletransmis, said processing device being characterized in that it is adapted to detect at least one information element (30) introduced in the stream to be transmitted, indicating a size of a part of the set of data present in the stream to be transmitted upstream of the information element and / or a size of a part of the set of data present in the stream transmitted downstream of the information element and in that it is adapted for processing said set of data based on at least one of said detected information element.

19. A data set processing device (4) according to claim 18, adapted to identify, as a function of the set of data received and at least one size indicated in said information element (30). , that data from the data set have not been received, and further identifying as a function of at least said indicated size, at least one segment (11a, 11g) of said set of transmitted data, in which the data are missing. 20. A processing device (4) of a data set according to claim 19, adapted for, following the reception of a retransmission of the data set of a stream to be transmitted comprising said set of data, record in memory, the segment (s) of said set of data identified during a previous remote transmission as missing data segments.

21. - Device for processing (4) a data set according to claim 20, adapted to determine a set of data corrected according to segments of said set of data recorded during a previous remote transmission and segment (s) of said set of data recorded during retransmission.

22. - Device for processing (4) a data set according to one of claims 18 to 21, adapted to detect an item of information (30) indicating a data size of all the data present in the stream to be transmitted upstream of the information element and / or a data size of all the data present in the stream transmitted downstream of the information element.

23. - Device for processing (4) a data set according to one of claims 18 to 22, adapted to detect an item of information (30) further indicating an identifier of the data set.

24. - Device for processing (4) a data set according to one of claims 18 to 23, adapted to detect elements of information in the stream to be transmitted at regular intervals or non-regular, each element of information indicating a size of a portion of all the data present in the stream transmitted upstream of the information element and / or a size of a part of all the data present in the downstream tele-transmitted stream of the information element.

25. - Device for processing (4) a data set according to one of claims 18 to 24, comprising a set-top box.

26. - Device for processing (4) a data set according to one of claims 18 to 25, wherein the data set comprises metadata and / or audio and / or video services of a service of TV in "Push" mode.

27. - Device for processing (4) a data set according to one of claims 18 to 26, wherein the detected information element indicates a number of next retransmission (s) of the data set.

28. - Data stream (FD VoD1) adapted to be transmitted between a transmitting device (2) and a receiving device (4), comprising a set of data, characterized in that it comprises at least one piece of information ( 30) indicating a size of a portion of the set of data present in the data stream, upstream of the information item and / or a size of a portion of the set of data present in the stream downstream of the information element.