Transmission method of digital services via network, and device for method realisation

FIELD: radio-engineering.

SUBSTANCE: invention refers to transmission of digital services, and namely to DVB- compatible services (digital video broadcasting). Method involves at least the following steps at which: receiver is connected to a stream of digital data in order to receive that stream of digital data; receiver extracts from the above stream the information on the network location, on the one hand, of streams transmitting contents of the above digital services, and on the other hand, of individual streams transmitting the information on the above digital services; receiver is connected at least to the stream of the above individual streams transmitting information that describes the service, in order to receive the information on those services; receiver uses that information for making the list that includes at least one service available in network.

EFFECT: receiver connected to bidirectional network identifies digital services in bidirectional network.

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The present invention relates to transmission of digital services, and more particularly services that are compatible with DVB standard (digital video broadcasting). DVB defines a service as "a sequence of programs under the control of the broadcasting station, which can be broadcast as part of the list" on the web usually type broadcast broadcast (terrestrial, cable or satellite), but also, especially in recent times, over an IP network-type, in other words, the network that supports Internet Protocol (IP). Specification IP can be found in RFC documents (request for comments), supported by the IETF (engineering problem group Internet under the number 791.

Recognition of digital services offered by the network, standardized by DVB in the context of satellite, cable or digital terrestrial transmission network. This standard is described in the document "Digital Video Broadcasting (DVB); Specification for Service Information (SI) in DVB Systems", published by ETSI (European Institute of telecommunications standards under the number ETSI EN 300 468. This document describes a set of tables containing information about the network, about the frequency at which the data streams containing the services transmitted on the services offered, etc. the Reader can also refer to the document "MPEG-2 system-ISO IEC 13818-1" to determine the format of the transport stream. The transport stream contains audio data, the VI is edanya, supporting data, such as subtitles, Teletext or interactive applications in the form of a simple flow, and the minimum required signal tables used to organize the content as a network information table (NIT), allowing other transport streams in the network to be found, the table associate programs (PAT) and a table of concordance programs (PMT) among others. These tables are combined into a transport stream, the receiver is configured with the data needed to connect to the first thread, allowing him to take these tables and create content database containing a list of services offered by the network, and data connections required to accept them.

With the proliferation of digital bidirectional data networks, particularly the Internet, and the aforementioned output high-speed services technical ability to transmit digital audiovisual services for this type of network is now available. Private, with a high data rate IP networks are developing for both corporate and home use. In this context, DVB is working to standardize the transmission of DVB services over IP networks. The working group, called DVB-IPI (Infrastructure Internet Protocol), is in the process of finalizing specifications the paths concerning the transport of DVB services over IP networks, and more specifically, recognition of these services. The proposal, as currently considered, are described in the document "DVB-IP Phase 1 Handbook" link IPI2003-227. The solution, as currently considered by the working group focused on the separation between broadcast services in the form of transport streams containing a single DVB service, on the one hand, and information describing these services are available in the form of XML files (extensible markup language)available terminals on request, for example, HTTP (hypertext transfer Protocol) may, for example, be used in order to find these files. This solution seems normal, because it exploits the bi-directional nature of the IP connection, as opposed to satellite transmission, for example. In practice standards, such as DVB, developed from a perspective of unidirectional transmission network, requiring that all information, which is probably useful for the receiver, transmitted constantly. The bidirectional nature of the considered networks means that the difference may be defined between information that is useful for decoding audiovisual services, and information description of services. These two types of information that are typically included in the DVB-stream, are not used simultaneously by the receiver. Their lane the cottage on the network can therefore be separated, thus providing a saving bandwidth by which signaling information is transmitted only on request, but not always in audio and video. In addition, providing information on network IP type from the HTTP server in the form of XML data files is the predominant solution that is widely accepted in this type of network.

However, this solution makes it necessary to develop a set of tools for the formation and management services, offering this signaling information in XML format. In fact, at the present time, the station broadcast broadcast content are managed infrastructure for the transmission of MPEG-2 DVB-services via satellite or cable. Since the adoption of this new signaling system means that new tools should be distributed in parallel with the existing system, operators must invest and take risk. In addition, the terminal does not currently contain the tools needed to analyze this information, such as an XML parser, for example. Combining these tools in an inexpensive receiver may be difficult or even impossible depending on the available hardware resources such as processor power or memory.

The image is the buy provides a method of digital services on the bidirectional network data and more specifically, recognition of the services offered in the network receiver. This method is used in DVB-context, allows most of the stages of the sequence of production, currently deployed for DVB services via satellite or cable, to be reused. This method will also allow you to limit the bandwidth used for the transmission of information for recognition of the services.

The invention relates to a method for recognizing a receiver connected to a bidirectional network, digital services in a bidirectional network, which includes a step in which the receiver is connected to the first flow, the stage at which the receiver extracts from the above-mentioned flow of location information in the network, on the one hand, streams, transmitting the contents of these services, and on the other hand, individual streams, transmitting information describing these services, the stage at which the receiver is connected, at least some of the threads that transmit information to describe services to obtain information about these services, and the stage at which the receiver uses this information to create a list of possible unitary, services available in the network.

According to a particular variant embodiment of the invention, all signaling tables relating to the service, contains at least one thread, well the stream, transmitting the contents of the aforementioned services.

According to a particular variant of the invention, the method includes a step for checking the correspondence between the identifier and the filter contained in the descriptor of the stream used to determine whether the table with this ID, in the mentioned thread.

According to a particular variant of the invention, the first IP address in the broadcast and the first port number entered by the user.

According to a particular variant of the invention, the first IP address and first port number is obtained from the network by the receiver.

According to a particular variant of the invention, the streams contain only one DVB-service.

According to a particular variant embodiment of the invention the list of services in NIT contained in the stream available on the first IP address broadcast by the first port.

The invention also relates to a device having means of connection to the IP address broadcast through the means of connection to an IP network and a means of decoding DVB-stream sent by this IP address broadcast, characterized in that the means of decoding DVB-stream has the opportunity analysis NIT extracted from the stream that contains the descriptors of the network correspond to the s IP network, and connect to each IP address broadcast described in the above-mentioned NIT to read it DVB-stream and extract from it the information about the services offered in the network, preferably according to any of the methods as defined above.

The invention also relates to handle services for broadcast DVB-stream for inclusion in the NIT, characterized in that it contains the IP address of the broadcast streaming server and the port number on which the said server transmits DVB-stream, transmitting the content services network IP type, and at least one descriptor that contains the IP address of the broadcast streaming server and the port number on which the said server transmits DVB-stream, transmitting signaling information on the aforementioned services.

According to a particular variant of the invention, the one or more descriptors containing the IP address of the broadcast streaming server and the port number on which the said server transmits DVB-stream, transmitting signaling information on the aforementioned services also contain a means of testing the correspondence between the identifier and the filter.

The invention will be better understood and other characteristics and advantages will become apparent upon reading below the following descriptions, referring to the accompanying drawings, among which:

figure 1 presents a diagram of the sequence of production DVB-services in the context of traditional satellite broadcasting;

figure 2 shows an example of the architecture of the DVB stream data in the context of one exemplary variant embodiment of the invention;

figure 3 shows an example of the architecture of the DVB stream data in the context of one exemplary variant embodiment of the invention;

figure 4 represents the operation of the receiver in the context of one exemplary variant embodiment of the invention;

figure 5 is a sequence diagram of production of DVB services in the context of one exemplary variant embodiment of the invention;

6 represents the structure of the NIT (network information Table) according to the DVB;

Fig.7 represents the structure of a standard digital decoder, for example, in the case of land acquisition;

Fig represents the structure of a digital decoder, suitable for reception by IP;

Fig.9 is a block diagram of the phase detection services;

figure 10 is a block diagram of the phase of the read information services.

Exemplary variant embodiment of the invention relates to the transmission of DVB services over IP networks, but can be applied to any other system for the transmission of digital services on the bidirectional network data.

The connection to the server over an IP network-type can be the t can be achieved by using IP multicast. One example of such a Protocol is the Internet group management Protocol Internet gateway), defined in RFC 2236. In this Protocol, the multicast server is associative multicast address. This address has the format of an IP address that is reserved for this purpose, but does not match the IP address of the machine, which can be accessed over the network. The receiver wants to connect to this server will send the request over the network that contains the IP multicast address. This request will be forwarded through the network until then, until it reaches a server that can respond to this broadcast, which will then register the receiver as client broadcast. The routers in the path between the server and the receiver will then be able to forward IP packets that make up the stream to a terminal subscribed to the broadcast. Knowing the IP address of the server machine in addition to the IP multicast address, an improved version of this Protocol can optimize the route passed through a subscription request, marshrutiziruya it directly to the destination server instead of broadcasting it all over the network. This improved version known as SSM (defined source multicast). Therefore, it is a system based on subscription broadcasting cyfrowy the data. The server transmits the digital data in packet form over the network. Until then, there is no receiver, the signatories to this broadcast, none of the package is not actually transmitted. When the receiver is signed, the packets are transmitted to him by routing through the network, following the route between the server and the client. The Protocol guarantees that packets will use only those routes network, which lead to the receivers that actually subscribe to the broadcast. When the receiver unsubscribes, the actual transmission of packets to the receiver stops. The Protocol also ensures that packets are not duplicated in the nodes of the route in the network, which leads to multiple receivers subscribed to the broadcast.

The transfer of data, which constitute the service can also be implemented using IP unicast. One example of such a Protocol is the Protocol stream real-time (RTSP), defined in RFC 2326. Since this Protocol is used to manage the stream broadcast over IP, it is designed to work in conjunction with the appropriate broadcast-based Protocol, such as RTP, the main difference from the system multicast is that for each client that wishes to connect to the stream, the server will initiate the translatio "point to point" between the server and the client. Obviously, this solution is more intensive in terms of bandwidth usage than the solution based on the multicast transmission. In practice, in this solution, the data packets travelling along part of the route network, which leads to a number of subscribed receivers are duplicated as many times as there subscribed receivers. This decision may be reviewed in the context of limited network in which only a small number of terminals are suitable in order to connect to the stream.

To limit the bandwidth used for transmission of DVB services over IP network, while limiting the modifications that must be made in the sequence of production services that are used by broadcasting stations, are already offering services of this type on other media transmission, such as satellite or cable, we will accept data organization, shaping services, as follows. On the one hand, the so-called flow installation will contain a table of information about the network, close inherited from the DVB NIT, and only this table, which we will call the modified NIT in the sense that it uses the same syntax as DVB NIT contains special handles, suitable for broadcast DVB services over IP. In addition, services will be divided into the content stream, which will bring the best simple audio, video and subtitles streams, and the streams of other services, as well as the minimum signaling used to organize these simple flows, such as PAT and PMT, and the stream descriptions, containing only the information of the service description. Only content streams will support the format of the transport stream, as defined by MPEG-2. The streams installation and descriptions directly compiled from tables, such as NIT flow installation and SDT or other tables for flow descriptions. These tables use the syntax sections MPEG-2. In practice, access to information describing the service is a single requirement, not in connection with the need to decode audio and video content. The current bandwidth in the IP and the need to limit the bandwidth of the network make it possible that a thread will be created for each service, but it is possible to combine several services into a single stream in the context of the invention.

In order to adapt NIT for use in the IP network must be defined descriptors applicable to location of stream in an IP network. This handle, suitable for use multicast, the following:

SyntaxThe number Bito the ID
Ip_stream_descriptor () {
Descriptor_tag8uimsbf
Descriptor_length8uimsbf
Content_multicast_address32bslbf
Content_multicast_port_number16bslbf
Content_multicast_protocol_mapping8bslbf
Content_source_address32bslbf
For (i=0; i < N; i++) {
Descriptor () }
}

Field "Descriptor_tag (tag descriptor)" is an identifier corresponding to the new type of descriptor.

Field "Descriptor_length (length descriptor)specifies the length of the descriptor.

Field Content_multicast_address (address multicast content)" specifies the IP address of mnogoe resnoy transfer server, which available content stream.

Field Content_multicast_port_number (the port number of the multicast content)" is the port number of the server to which the receiver should connect in order to receive the content stream.

Field Content_multicast_protocol_mapping (according to the Protocol multicast content" - this field identifies the Protocol encoding all or each service, transmitted by this address. The Protocol can be MPEG-2, MPEG-4, MHP or the other. This optional field can be used to filter by content type to save only those services that the receiver is able to decode.

Field Content_source_address (address of the content source)" is a real IP address of the server that provides efficient routing of the connection request to the multicast server according to the SSM Protocol.

The cycle descriptors used to manage handles detection of all or each thread descriptions relating to the service that contains content that is broadcast on a previously defined address.

The following is a description of another example of such a handle, suitable for use for unicast transmission:

Ip_stream_descriptor () {
Descriptor_tag8uimsbf
Descriptor_length8uimsbf
Content_unicast_address32bslbf
Content_unicast_port_numberbslbf
Content_unicast_protocol_mappingbslbf
For (i=0; i < N; i++) {
Descriptor () }
}

Field "Descriptor_tag" is an identifier corresponding to the new type of descriptor.

Field "Descriptor_length" specifies the length of the descriptor.

Field Content_unicast_address (address unicast content)" specifies the IP address of the unicast server, which is available to stream, transmitting the content.

Field Content_unicast_port_number (the port number of unicast content" is the port number on the server to which the receiver should connect in order to receive the stream, transmitting the content.

Field Conent_unicast_protocol_mapping (according to the Protocol unicast content)" - this field identifies the Protocol encoding all or each broadcast services at this address. This Protocol can be MPEG-2, MPEG-4, MHP or the other. This optional field can be used to filter by content type to save only those services that the receiver is able to decode.

The cycle descriptors used to manage handles detection of all or each thread descriptions concerning the service, the contents of which are broadcast on a previously defined address.

We will see in the structure of the DVB NIT and, therefore, the modified NIT that there is a cycle in traffic flow, which means that all traffic flows that make up the entire network broadcasting station can be described in this cycle. In this way the receiver can make a list with the IP addresses to multicast or unicast traffic flows broadband TV broadcast over IP network. The list of descriptors services may not necessarily be included in the modified NIT in order to accelerate the establishment phase of the receiver.

Can also be considered the servers stream multicast and unicast present in the same network.

In another, more complex implementation descriptors location information descriptive of threads related to passing the emnd service you can, for example, take the following form:

Ip_stream_multicast_locator_descriptor () {
Descriptor_tag8uimsbf
Descriptor_length8uimsbf
Filter_length8uimsbf
Filter_descriptor()
multicast_address32bslbf
multicast_port_number16bslbf
multicast_protocol_mapping8bslbf
source_address32bslbf
}

Here we'll find the standard descriptor fields to determine the location of the broadcast stream for IP multicast mode. Only fields Filter_length (filter length)and Filter_descriptor (filter descriptor)" require clarification. The prospect is ctice, in the illustrative context of a variant embodiment of the invention, the information describing the service is separated from the information content and is transmitted in some other thread. In addition, it is also possible to transmit this signal information, i.e. these tables, in many different threads. Absolutely right to take this possibility into account that the descriptor "Ip_stream_descriptor" contains a cycle. In addition, when this descriptor is being scanned does not have to know what the flow in the cycle descriptors will contain the table that is searched for services affected by the descriptor. Action from the introduction of the fields "Filter_length" and "Filter_descriptor" in the descriptor makes it possible to implement a means for storing descriptor information to determine which tables are contained in each thread in a loop. One way to encode this information may be, for example, to place in this field "Filter_descriptor strings of bits used, for example, to program the demultiplexer in order to filter the tables. As each table type has an assigned identifier, the filter can be programmed using bit strings representing the ID of the table contained in the stream. In cases where it is desirable to be able to have a number of tables in the stream can be passed with the persons, used to program the filter demultiplexer. The first string specifies the identifier that must be filtered and the second line the same length specifies for each bit of the first line, defined or not this value. This ID will therefore correspond to the filter, if for each bit of the identifier, for which the corresponding bit of the second bit line is set to one, the corresponding bit of the first row has the same value. For example, when considering strings of three bits of the first bit string in 0b101, the second string value 0b110 - IDs matching this filter will have values 0b101 and 0b100. This method can be used to determine the tables that are contained in the stream, in the same way as the demultiplexer will be programmed to look for them.

In another, simpler implementation, the descriptor descriptive information flows relating to the service broadcast, may, for example, take the following form:

Ip_stream_multicast_locator_descriptor_table_ids () {
Descriptor_tag8uimsbf
Descritor_length 8uimsbf
NbOfTableIDs8uimsbf
TableIDList()
multicast_address32bslbf
multicast_port_number16bslbf
multicast_protocol_mapping8bslbf
source_address32bslbf
}

Here we'll find the standard descriptor fields used to determine the location of the broadcast stream for IP multicast mode. Only fields NbOfTableIDs" and "TableIDList" require explanation.

Field TableIDList" corresponds to the list of identifiers of the tables that are included in the appropriate thread, and the "NbOfTableIDs" represents the number of table identifiers included in the list. Thus, the stream containing information relative to the signal information about current and future events of the current thread, for it is which the ID of the table is equal 0x4E, and signaling information about current and future events other threads for which the ID of the table is equal to 0x4F, will have a descriptor with a value of 2 for "NbOfTableIDs and value 0x4E and 0x4F in the "tableIDList".

Another possibility broadcast streams containing signaling information may be to choose a simple file transfer Protocol between the server and the receiver Protocol instead of multicast. Such a Protocol may for example be a hypertext transfer Protocol (HTTP). This Protocol is simple to implement, especially if it is limited to the realization of the possibility to perform a "GET"to retrieve the file from the server. This Protocol is much simpler than XML, in order to control the processing of the file described in the introduction. In this case, it is important to have a different handle, such as handle below, which is used to associate with the table ID, the URL (uniform resource locator) of the file that contains this:

Ip_stream_HTTP_locator_descriptor () {
Descriptor_tag8uimsbf
Descriptor_length8 uimsbf
Table_id8bslbf
For (i=0; i<N; i++) {
Char8bslbf
}
}

However, this method is not preferable embodiment of the invention, since broadcast broadcast via HTTP, exactly the same as for unicast transmission of these signaling tables, includes the duplication of the data stream over the network for each receiver that you want to install. Besides this, however, is an embodiment, which may be considered in networks that do not contain a lot of receivers, such as home networks.

Figure 1 describes the overall architecture of the sequence of production of MPEG-2 DVB-services in the context of satellite broadcasting. At the beginning of the sequence there is audio and video content 1.1, which should be transferred. This content is encoded according to the MPEG-2 encoder 1.2 in order to form a simple audio/videopost what to 1.5. In parallel with the encoding of audio and video content is generated signaling information 1.3, which is typically generated from a database containing information describing a service that needs to be translated. This information is generated in the form of a signal flow 1.6. Another module 1.4 controls the generation of flow 1.7 subtitles. It is also possible to enable a flow of 1.8 interactive applications, the production sequence which is not described in detail herein. All of these simple threads with other threads, if necessary, transmitting more audio and video content, or other related alarms, are then combined in the multiplexer 1.9 to generate a transport stream MPEG-2, which is then modulated and converted to the frequency selected by the modulator/Converter 1.10. The set of threads of this type can be mixed by the mixer 1.11 for transmission to the satellite 1.13 through the station 1.12 transmission. In this case, the required synchronization signaling information between different threads in order to include information about other threads in the tables describing each thread. These programs can then be taken home user through a satellite antenna 1.14 to be decoded by the decoder of the television signals and displayed on the TV. This system is mA currently is quite within the capabilities of the stations broadcast.

Figure 2 shows an example of the architecture of the stream according to an exemplary variant embodiment of the invention. In this example, the first flow 2.1, called thread installation. This thread installation does not contain audio or video content, but only modified NIT 2.4, containing network information. This thread installation can directly use the syntax of MPEG-2 sections and does not require encapsulation of signs in the form of a transport stream due to the fact that the data is directly transmitted over the IP network.

This modified NIT describes the number of threads that contain services. Standard structure NIT, as defined by DVB, is shown in Fig.6. Although the stream, regardless of the transmission medium may contain a number of DVB services, perhaps for reasons of bandwidth that only threads containing only one DVB-service, will be used in the initial stage in the context of the broadcast IP. Therefore, the example described in figure 2, reflects this case. However, it is obvious that the invention is not limited to the use of streams containing only one DVB-service flow. Therefore, we have modified NIT 2.4 description of the three services 2.5, 2.6 and 2.7. Service description will contain descriptors 2.8 and 2.9 to determine the location of the flow 2.2 content, as well as stream containing the description relating to the contest shall be services 2.3. Flow 2.2 content will contain PAT (table associate programs)indicating the contents related to the service 2.11 composed of PMT (table compliance programs). The flow 2.3 description therefore is a separate thread from the previous. This thread has no format transport streams MPEG-2, and table directly with the syntax section MPEG-2. This separation allows the client to connect to this stream, only when you need to access the information, descriptions, and therefore avoids the bandwidth usage for the permanent transfer of this information. Thus, the use of this bandwidth is improved. Recall that when broadcast over IP, when the receiver unsubscribes from broadcast, the actual transmission of packets over the network to this receiver is terminated. In the example, the flow description contains information about events 2.14, such as information from the current event to the next event, and, where appropriate, a complete calendar of events, so that may be generated electronic guide program. It also contains information about the service 2.13, such as SDT (table service description).

Figure 3 is another example of the architecture of the stream according to an exemplary variant embodiment of the invention. This example is more simple in comparison with the pre is Adumim, which is represented in figure 2. The difference is that in this case the information of the description relating to events, and information related to the service are transmitted through two different threads. So in this case we have for services 1 3.5 three of the mapped descriptor 3.8, 3.9 and 3.10 instead of the previous two, pointing to the stream 3.2 content stream 3.3 information about the service and the flow of 3.15 information about the event. Therefore, it is possible to separate different tables that comprise signaling information in different streams according to the tables and use that will be made of them, in order to manage the network bandwidth. It is also possible to take into account the limitations of the service management, grouping together the tables that have the same refresh rate.

Figure 4 presents a diagram showing the participants, describing the phase detection services available in the network. Objects represent, on the one hand, the system user who looks your receiver, the receiver and the streams installation, service content and service description. Other threads related to other services, may be present in the network, but not shown in figure 4. In the initial stage, the user turns on his receiver. The receiver then connects to the flow of the installation. The receiver has parameters, once chausie him to connect at the initial stage to the IP address multicast or unicast. The simplest solution is to accept that this IP address broadcast manually entered in the configuration menu. This is the IP address of the broadcast may also be assigned to the receiver in-phase connection via protocols such as DHCP (dynamic host configuration Protocol dynamic host configuration) or PPP Protocol (point to point). However, there is any other way of determining that the first IP address. This address consists of an IP multicast address or a unicast transmission and the corresponding port number. The installer flow transmitted by this email.

Since the receiver is connected to the flow of the installation, it can decode the modified NIT and read the information contained in it. Therefore, the receiver is able to create a list of services available in the network. Scanning this list gives him access to the addresses broadcast content streams and broadcast streams descriptions on the network. Therefore, this receiver can be connected, in turn, to these threads to gather information about the services, which includes the name of each service. This means that it is then possible for the receiver to provide a list of services to the user. The user then selects the service, which he wants to view, and the receiver uses the thread handle of the content found in the modified NIT for the selected services, and connects to the flow of the contents of the selected services is I. Then can start decoding and displaying the selected services. If the user then wishes to access information about the current event or the next event, it sends a request to this action, and the receiver will again use the descriptor contained in the modified NIT, in order to find the location in the stream network descriptions containing information about events. This information may be contained in the same thread as the information describing the services, or in a separate thread, as described in figure 2 and 3. The receiver then connects to this thread and find information about events so that it can display information to the user.

The receiver can be connected to the stream, for example, through IGMP. Usually this transport stream is encapsulated MPEG-2 over IP type, using the levels of IP/UDP/RTP Protocol (user datagram Protocol real-time), but can also be MPEG-4, MHP or stream of another type.

Figure 5 represents the sequence of production facilities according to the invention. First, the raw audio and video content 5.1 encoded by the encoder 5.4 in order to give a simple audio and video streams 5.7. Base 5.2 data contains a full description of services and information about events. Module 5.5 is used to create a signaling table 5.8 with this info what Razia. Signaling information 5.8, threads 5.7 audio and video content and other optional information, such as interactive and other applications 5.6, combined 5.9 to create a thread 5.10 content. The first module 5.11 format uses signaling table 5.8 created, where necessary, from information contained in the database 5.2 data and additional information about other services 5.3, in order to create a thread 5.12 description. The second module 5.13 format uses additional information about the network services 5.3 in order to create a thread 5.14 installation, which will contain a description of all the threads available in the network with addresses that provide access to them. The main modules that do not exist in the traditional sequence of production DVB-services, are these modules 5.11 and 5.13 format. However, these modules are simple to create because they just create threads containing signaling tables, such as those that are already established signaling module 5.5, innovation is generated from the use of descriptors that are appropriate in order to determine the location of the flow in an IP network, whether this stream in multicast mode or unicast or even accessible via the file transfer Protocol such as HTTP. These threads 5.10, 5.12 and 5.14, once created, can then be transferred to the servers IP network.

Fig.7 describes the architecture of the traditional decoder, such as a digital terrestrial decoder. The decoder 7.1 has a screen 7.3. The 7.2 user interacts through the application 7.4 browser, which is displayed on the screen 7.3. All functions of the decoder are controlled by the control application, traditionally referred to as middleware 7.5. This application controls the hardware modules, namely tuner 7.8, the demultiplexer 7.7 and decoder 7.6. The tuner is responsible for the restoration of the DVB stream, received by the antenna 7.9. This thread demultiplexes the demultiplexer, in other words, the demultiplexer capable to recreate a different elementary stream, which constitute the transport stream DVB, such as audio, video and auxiliary data (e.g., captioning, Teletext or interactive application) or a separate signaling table. In DVB-stream every simple stream is identified by an identifier, and the demultiplexer can be programmed to filter out full stream, which is accepted, simple flows that are of interest to us. At least the audio and video streams are encoded to compress and/or encrypt the information they contain, and the decoder in order to decode and/or decrypt these flows in order to restore audio and videocodecid the e to the user.

Fig describes the IP decoder designed to receive DVB-streams over the IP network. The architecture is exactly the same as in the conventional decoder, the difference is that the tuner is replaced by a network interface 8.10 connected to an IP network 8.11.

Figure 9 details the steps for recognition of services in the network. The first step consists in obtaining flow 9.1 installation. This thread is available in the network. There are many ways to make this thread available, of which at least three can be mentioned, and this stream can be transmitted in the multicast mode, and can also be transmitted in unicast mode, or can be accessed via the file transfer Protocol, such as HTTP, for example. Not paying attention to how this thread installation is broadcast over the network, the decoder must be able to accept him, so he must know the address and connection parameters to connect to this stream. The first address can be either represented in the permanent memory of the device, or to be transferred by the user or even be transferred to the device server when connecting to the network via the communication Protocol, allowing to obtain parameters such as DHCP Protocol (dynamic host configuration) or PPP Protocol (point to point). The receiver connects to the flow 9.2 setup and then not looking at the modified NIT 9.3. When this modified NIT is found, it reads in this modified NIT description of the first transport stream, characterized by its ID (TSID) of the transport stream and its original network ID (ONID) 9.4. Then, as the transport stream can contain a number of services, the receiver begins to read the service description contained in the transport stream. For each service, the receiver starts reading service identifier and data to determine the location of the flow 9.5 content. For each service, information about this service can contain many threads describing services. The location of this set of threads of the description is in the sequence of descriptors, which are now shown as 9.6 and 9.7. Then for each service is stored identifier of the transport stream, the initial network ID, service ID, the descriptor of the location of the stream, transmitting the contents of the services (CSL denoting the index of the location of the content stream"), as well as a table of pointers to the location of the stream description of services (SDSL) 9.8. These operations are repeated for each service contained in the transport stream, as well as for each transport stream 9.9 and 9.10. In this way a list of all services available in the network, it turns out, together with descriptors broadcast streams passing them as for the content, and information describing the content.

Figure 10 details the example of the way in which information about the services can be restored, because the list of services was created by scanning the modified NIT, as explained in figure 9. In order to recover information about the different services offered in the network, the receiver must find the table (SDT) of the service description for each service. To do this, it starts by reading the descriptor of the first services 10.1. He then reads the first location index stream service description (SDSL). Then, if this SDSL does not contain the fields "Filter_length" and "Filter_descriptor"that provides information about whether the assigned flow SDT, it should connect to the stream 10.9, read from this stream section in search of SDT, for which the ID of the table is equal 0x42, 10.10, 10.11 and 10.12. In the case where the field "Filter_length" and "Filter_descriptor" exist, it will use these objects information in order to verify the presence of SDT in the stream 10.3. If it is not present, it tests the following descriptor 10.13, 10.14 and finishes, removing from list service for which he cannot find SDT 10.15. When he found the stream containing the SDT, it reads this table 10.5 and finds in it the name of the service and the service provider, which it stores in memory 10.6. This operation is repeated for all services, 10.7, 10.8 until the end of the list s is g 10.16.

The invention allows the broadcasting stations to re-use most of their existing production sequences, in particular the multiplexers. Development is needed only in those of formatters for creating streams containing only signal table, all or part of them and, where necessary, without encapsulating them in a transport stream. This development is minimal. The invention also limits the modifications that can be done in software running on the decoders. In practice, mainly the part that manages the IP interface instead of the interface cable or satellite reception, must be added, while the application that manages the installation must be slightly modified. All the other operations of the device are the same as for the standard decoder. Similarly, the access control can be reused identically. The invention therefore makes it possible to receive the broadcast of DVB services over broadband IP networks by minimizing investments and risks for broadcasting stations and the use of available network bandwidth.

1. Method detection receiver is connected to a bidirectional network, digital services in a bidirectional network, characterized in that it contains at least the following steps, are:
a receiver connected to a digital data stream for reception of the digital data stream;
the receiver extracts from the above-mentioned flow of location information in the network, on the one hand, flows, transferring the contents of specified digital services, and, on the other hand, individual streams that carry information describing these digital services;
the receiver is connected, at least to some thread of these individual streams that carry information to describe services to receive information about these services;
the receiver uses this information to compile a list containing at least one service available in the network.

2. The method according to claim 1, in which all signalling tables relating to the service, contains at least one thread other than the thread that transmits the contents of the aforementioned services.

3. The method according to claim 2, which contains the stage at which test the correspondence between the identifier and the filter contained in the thread handle, used to determine whether the table with this ID, in the mentioned thread.

4. The method according to claim 1, wherein the first IP address of the broadcast and the first port number entered by the user.

5. The method according to claim 1, wherein the first IP address of the broadcast and the first issue of the ORT is obtained from the network by the receiver.

6. The method according to claim 1, in which threads contain only one DVB-service.

7. The method according to claim 1, wherein the list of services is included in the NIT contained in the stream available on the first IP address broadcast by the first port.

8. A receiving device for reception of digital services through a bidirectional network, having means of connection to the IP address broadcast through the means of connection to an IP network and a means of decoding broadcast DVB-flow in this IP address, broadcast, characterized in that the means of decoding DVB-stream has the ability to retrieve location information flows in the network from NIT, extracted from the stream that contains the descriptors of the network that are appropriate to an IP network, and the ability to connect to each IP address broadcast described in the above-mentioned NIT, in order to believe in it DVB-stream and extract from it the information about the services offered in the network, according to the method according to any one of the preceding paragraphs.



 

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