FR3002718A1 - Method for processing multiplex i.e. transport stream in terminal i.e. set-top box, involves recording digital data packets of program selected in file transport stream between start time and end time - Google Patents

Abstract

The method involves receiving a multiplex i.e. transport stream (TS) (E2), and selecting a digital program (P1) from the transport stream (E1). A start time (T0) and an end time (T1) are selected, and digital data packets of a program selected in a file transport stream (FTS) are recorded between the start time and the end time, where the positions (IDX) of the digital data packets are recorded in an index file (20). The positions of the digital data packets are acquired for reading and decoding the digital data packets. Independent claims are also included for the following: (1) a terminal (2) a computer program for processing a transport stream.

Description

Processing of a video multiplex. TECHNICAL FIELD The invention relates to the audiovisual field. The invention is particularly applicable to the processing and recording of audiovisual digital content broadcast on a broadcast network of such content. STATE OF THE ART Digital television contents are today broadcast in the form of multiplexes in broadcast networks. In a multiplex, several channels, or programs, are combined (multiplexed) in order to be broadcast at the same time on the same frequency. By program, we mean all the digital components (audio, video or data) which constitute what is commonly called an audiovisual chain, that is to say a temporal sequence of contents, or events, audiovisuals (films, TV shows, games, etc.). When a user of digital content makes the request to receive a program, the multiplex is received in its entirety by its receiving terminal. Such a terminal, also called STB (English Set Top Box), comprises at least one demodulator (in English, tuner) capable of receiving the multiplex and a demultiplexer able to extract a program. Thus, when the user selects a given program from all the broadcast programs offered to him, the tuner selects the multiplex, receives it, demodulates it and transmits it to the demultiplexer which extracts the received data packets in order to reconstitute the required program. .

If the user wishes to record two different programs of the multiplex at the same time, he must have two tuners, even if both programs belong to the same multiplex.

To remedy this problem, a simple solution is to use a single tuner and record the entire multiplex. When replaying, only the required programs should be selected. However this solution is unnecessarily expensive, because in such a context, even the programs of the multiplex which were not required are recorded. To improve this solution, it has also been proposed to use a single tuner to record only the requested programs, each in a separate file, to facilitate replay. This solution results in a noticeable drop in the performance of the storage device, since such a write (and read) mechanism must make constant round trips between the different files constituting the program recordings. The invention offers a solution that does not have the drawbacks of the state of the art. The invention For this purpose, according to a functional aspect, the subject of the invention is a method for processing at least one multiplex comprising at least one digital program consisting of digital data packets, comprising the steps of: minus one multiplex; - selection of at least one program; - selection of a start and end time; recording, between the start time and the end time, packets of said at least one selected program in a multiplex file. The invention thus makes it possible to record an entire multiplex using a single tuner, while not overloading the hard disk: only the packets resulting from the programs required by the user are recorded. The writing also respects the linear structure of the multiplex, thus facilitating a subsequent replay: if two programs have been selected, the replay makes it easy to find them in the multiplex file while saving the displacements of the storage disk read heads. According to a particular embodiment of the invention, the method is characterized in that it furthermore comprises, if at least two received multiplexes respectively comprise at least one selected program, a step of remultiplexing the selected programs in the file. multiplex. By remultiplexing is meant here the constitution of a single multiplex from several input multiplexes. Thus, the invention makes it possible to generate a single multiplex recorded in a multiplex file, even if there are several input sources: all the programs of all the sources are optimally recorded in a single multiplex file, offering a replay easy programs required for later viewing, without unnecessary displacement of the read heads. According to a second particular embodiment of the invention, which may be implemented alternatively or cumulatively with the previous one, the method according to the invention further comprises a step of recording the positions of the data packets of the selected programs. in the multiplex file. The invention thus offers direct access to the packets of a program (from any multiplex) during the replay, without having to search the information in the packet headers: it is sufficient to read the position of a packet as it was registered, and then directly access said packet from that position. According to a variant of this second embodiment, the positions of the packets are further recorded in an index file. The storage, in this index file, of the position data makes it possible, in a way, to produce a virtual file system (in English: vfrtual file system) for access to the data of the multiplex file. It is thus possible to overcome, by reading this single file, the reading of the packet headers of the multiplex by directly accessing, via their position, or address, stored in the file, to the packets of the selected programs. According to a second variant of this second embodiment, which may be implemented alternatively or cumulatively with the previous embodiment, the method further comprises a step of restoring a digital program of the multiplex file, comprising the sub-steps of: acquiring the positions of the data packets of the program to be restored; - reading and decoding data packets.

The index file is accessed to obtain the addresses of the packets on the disk. Thus, everything happens, during the replay, as if the program was directly accessible in a single file. The replay mechanism is transparent to the user and provides the best data access performance on the disk.

According to a material aspect, the invention also relates to a terminal comprising at least one demodulator able to receive at least one digital program multiplex and a recording medium able to record digital data, characterized in that it comprises: module capable of selecting at least one program to record in at least one multiplex; a module able to select a start and end time; A module capable of recording, between the start time and the end time, the packets of the at least one selected program in a multiplex file on the recording medium.

According to another material aspect, the invention also relates to a computer program capable of being implemented on a terminal as described above, the program comprising code instructions which, when the program is executed by a processor, performs the steps of the method of processing a multiplex defined above. The invention will be better understood on reading the description which follows, given by way of example and with reference to the accompanying drawings.

The figures: FIG. 1 represents the general context of the invention; FIG. 2 represents the architecture of a digital decoder capable of implementing one embodiment of the invention; Figure 3 schematically shows the constitution of a video multiplex; FIG. 4 schematically represents the steps of a recording according to one embodiment of the invention; FIG. 5 schematically represents the steps of a recording according to a second embodiment of the invention.

Figures 6a and 6b respectively illustrate the structure of the data according to the state of the art and this second embodiment. DETAILED DESCRIPTION OF AN EMBODIMENT EXCHANGING THE INVENTION FIG. 1 represents the general context of the invention. This is for example a digital broadcast network DVB (acronym for Digital Video Broadcast, a set of digital television standards issued by the European consortium DVB). The underlying infrastructure may be satellite (1) or digital terrestrial television (DTT) (2), as shown schematically in the figure, or cable, not shown. Different broadcast programs (5) are distributed in different transport streams (TS), also called multiplexes. The multiplexes are received by users digital decoders (STB, 6) via appropriate reception media (antennas, cables, etc.) and the various programs that constitute them (5) are made available to a user, for example to for viewing purposes on a television (7).

FIG. 2 represents the architecture of a digital decoder capable of implementing an embodiment of the invention, for example the decoder (6) of FIG. 1. Such equipment, also called STB (of the English language) Set Top Bof, is able to receive different transport streams (denoted TS, of the English Transport Stream) thanks to tuners In the example of Figure 2, the decoder includes two tuners (TUNER, 10,11) , which allows it to receive both two multiplexes (TS1, TS2) coming for example respectively from a satellite network (3) and a TNT network (4) Each of the two tuners can demodulate the received multiplex and transmit it to a demultiplexer (DEMUX) which extracts the data packets and transmits them to the decoding module (DEC) which decodes the audio-visual data packets in order to present them to the users The presentation may be conditioned by the rights users (some feeds nsports may be accessible to some users and others not, just like some programs inside a transport stream).

The decoder (6) also conventionally comprises memories (M) associated with a processor (CPU). The memories can be ROM (Read Only Memory) or RAM (Random Access Memory) or Flash, etc. The decoder (6) communicates with the outside, in particular the television (7) via an input-output module (IO) which can for example be of the HDMI (High Definition Multimedia Interface) type. It also communicates with a recording medium, for example a hard disk (8), which may be internal or external (for example, remote in the network) via another input-output module (R / W).

The decoder (6) further comprises a recording control module according to the invention, hereinafter called REC (English Record). The REC module, which can be software or hardware, is in particular capable of controlling the writing of audiovisual data on the disk via an input-output module (R / W) and reading these data on the same disk before, for example, a visualization of one of the recorded programs. The REC module is associated with a data multiplexing module (MUX), the purpose of which is to reconstruct a single recorded multiplex from several input multiplexes, as will be described later in support of FIG. these modules communicate classically via a data bus (9). FIG. 3 schematically represents the constitution of a video multiplex according to the state of the art, for example a transport stream (TS) according to the DVB standard; the constitution of the multiplex can be broken down into three steps denoted respectively A, B and C in the figure. Each audiovisual program (P1, P2, P3, P4) is represented on the left of the figure (step A) by a data segment between a start time (TO) and an end time (T1) on a time axis. (t). During the preparation of the flow, each of the programs is conventionally divided into data packets (step B), for example in accordance with the ISO / IEC 13818 standard, better known by the acronym MPEG-2, for transport and synchronization. audiovisual data.

The resulting packets of the different programs are multiplexed into a transport stream (TS) as shown in step C. Each data packet is identifiable in the stream TS by a set of characteristic header data, including a flag of the component (audio, video, etc.) and the program ("PiD" according to the aforementioned MPEG-2 standard) to which it belongs, which defines a single sub-stream, and the packet number in this sub-stream, which allows scheduling packages. In this example, it is assumed that the user is interested in an event of the program P1 (for example, a movie) which starts at the instant TO (eg the start time of the film credits) and an event P2 program (for example, a sequence of information) that starts later than TO and also ends later, at time Ti (end of the show). FIG. 4 diagrammatically represents the steps of a recording according to one embodiment of the invention, in the case where the decoder is equipped with a single tuner, and can therefore receive a single multiplex (TS) at a given instant. It is recalled that the object of the invention is to record on the disk the programs required by the user, in the most efficient manner, that is to say without unnecessary displacement of the read and write heads of the disk, without writing unnecessary data, and with easy proofreading. During a first step El, the user selects two programs for recording, for example "Orange Sports" (PI) and "Orange TV" (P2). This selection is transmitted to the decoder (STB, 6) which then controls its tuner so as to receive (step E2) the multiplex of the desired programs (which is supposed to belong to the same multiplex). The user also specifies the beginning (TO) and the end (Ti) of the desired recordings, for example it may be the start and end time of an event (a movie and a broadcast) of the channels " Orange Sports "(PI) and" Orange TV "(P2), as shown in Figure 3. More precisely, according to this example, TO is the start time of the first event selected in the PI program and Ti is the instant end of the selected event of the program P2 that ends later. During a step E3, the pilot program of the recordings according to the invention (module REC of FIG. 2) controls the recording on the hard disk (8) of all the packets composing the multiplex for the selected programs (P1 and P2) between the two moments TO and Ti. Thus, it is sort of a "drilled" version of the multiplex, named FTS (for: File Transport Stream) that is recorded on the hard disk. Naturally, this representation is very pictorial since the data packets are written linearly, sequentially, on the disk, the "holes" represented by absences of packets in the example of Figure 4 remaining virtual. This linearity ensures that the read heads move as little as possible when writing and replaying packets on the disk. Parallel to the writing on the hard disk, the REC module according to the invention can record, according to a variant, the position (IDX) of the packets in a file called index file (20). This record will subsequently allow direct access to packets in the recorded stream without having to read through the data packets to access their identifiers (Pid). During a step E4, the user requests to view a recorded program event, for example a P2 transmission. The REC module according to the invention then supports the reading of P2 program packets on the disk. Two cases may arise: - if it does not have the file 20 according to the recording variant discussed above, the REC module can read back the packet headers in which it finds the relevant information, and do not hold in read that the registered multiplex packets (FTS) which correspond to the program 2 (gray packets not hatched in the figure). if it has the file 20 according to the recording variant discussed above, it can simply use this file to directly access the P2 program packets, without necessarily reading their contents on the disk. This leads to a data management that can be assimilated to a file management via a virtual system (vfrtual file system in English): everything happens, for the user, and for the STB, as if each of the programs (P1 and P2) was stored on the disk in an individual file that it is sufficient to read between two positions (index).

During a step E5, the data stream corresponding to the P2 program is conventionally decoded and transmitted to the television which can display it for the user (step E6).

FIG. 5 diagrammatically represents the steps of a recording according to a second embodiment of the invention, in the case where the decoder (6) is equipped with two tuners (10, 11), and can thus receive two multiplexes (TS1 , TS2) at a given moment. The object of the invention is to record the programs required by the user on the disk, in the most efficient manner, that is to say without unnecessary displacement of the writing heads, without writing unnecessary data, and while ensuring easy replay. In this perspective, the various demultiplexing modules (DEMUX, two in this example) are associated with a data remultiplexing module (MUX), the purpose of which is to reconstitute a recorded multiplex (FTS for File Transport Stream). from two "hole" multiplexes from the two input multiplexes. Note that, according to this example, in order to keep an exploitable final file, it may be necessary to modify part of the additional data of the recorded flows, such as the headers, including the data (program number "Pid", etc. .) can conflict. It will therefore be preferable, when remultiplexing, to process these flows by adapting these references while keeping the integrity and consistency of the recorded data. This type of adaptation will not be detailed further because it is within the reach of the skilled person with knowledge of digital video broadcasting standards (DVB). FIG. 6b illustrates the advantage of this solution compared to the state of the art shown schematically in FIG. 6a. In the state of the art according to FIG. 6a, the different programs originating from the two multiplexes (TS1, TS2) represented at the input are stored in different files: a file F3 for the program P1 of the first multiplex (TS1), and two Fl and F2 files for P2 and P3 programs from the second multplex (TS2). The invention, as represented in FIG. 6b, makes it possible to remultiplex the data coming respectively from multiplexes TS1 and TS2 to form a single file on the disk (FTS). During writing, the data packets from the three programs P1, P2 and P3 of the two multiplexes are written sequentially in the FTS file. It goes without saying that the embodiment which has been described above has been given for purely indicative and not limiting, and that many modifications can be easily made by those skilled in the art without departing from the scope of the invention.

Claims (7)

REVENDICATIONS1. A method for processing at least one multiplex (TS) comprising at least one digital program (P1, P2, P3, P4) consisting of digital data packets, comprising the steps of: - receiving (E2) said at least one multiplex ( TS); - selecting (El) at least one program (P1); - selection of a start time (TO) and end time (T1); recording, between the start time (TO) and the end time (T1), packets of the said at least one selected program in a multiplex file (FTS). 2. Method according to claim 1, characterized in that it further comprises, if at least two received multiplexes (TS1, TS2) respectively comprise at least one selected program (P1, P2, P3, P4), a step of remultiplexing selected programs (P1, P2, P3, P4) in the multiplex file (FTS). 3. Method according to claim 1, characterized in that it further comprises a step of recording the positions (IDX) of the data packets of the selected programs (P1, P2) in the multiplex file (FTS). 4. Method according to claim 3 characterized in that the positions of the packets (IDX) are recorded in an index file (20). 5. Method according to claim 3, characterized in that it further comprises a step of restoring a digital program (P1) of the multiplex file, comprising the substeps of: - acquisition of the positions (IDX) of the data packets the program to be returned (P1); - reading and decoding data packets. Terminal (STB) comprising at least one demodulator able to receive at least one digital program multiplex (TS) and a recording medium (8) capable of recording digital data, characterized in that it comprises: module capable of selecting at least one program to record (P1, P2) in at least one multiplex (TS); a module able to select a start time (TO) and end time (T1); a module able to record, between the start time (TO) and the end time (T1), the packets of the said at least one selected program in a multiplex file on the recording medium. 7. A computer program adapted to be implemented on a device as defined in claim 6, the program comprising code instructions which, when the program is executed by a processor, performs the steps of the method defined according to the claim 1.15