What is rtrs multiplex splicing. Methods of TV broadcasting in the dvb-t2 standard with the insertion of regional content. Network broadcasting systems architecture with digital program insertion

An analysis of the methods of organizing the broadcasting of the First multiplex in the DVB-T2 standard with the insertion of regional content in various options for building single-frequency SFN networks of digital terrestrial broadcasting in the Russian Federation is presented. The problems of import substitution of the technology of distributed modification of programs using a replayer are noted, since Enensys Technologies owns a Russian patent for a method of broadcasting DVB-T2 with the insertion of regional content and a device used in this method. The disadvantage of the technical solutions used in the Russian Federation to implement the task of delivering the regional version of the First multiplex is the need to broadcast combined T2-MI streams in different regions with uniform parameters set in the federal multiplexing center (FCFM). The uniform parameters set in the FCFM lead to a number of problems associated with different broadcasting conditions by the territorial location of transmitters, by the type and intensity of interference, as well as by different climatic and geographical conditions of broadcasting on the territory of the Russian Federation. The DVB-T2 broadcasting standard allows providing a wide range of parameters for the created SFN networks for their adaptation to the working conditions. It is necessary to select a guard interval for a specific topology of transmitter placement. To ensure synchronous operation of transmitters of a single-frequency network, a time stamp is set based on the resulting time delays of the information signal. The type and intensity of interference, geographical conditions of broadcasting depend on the choice of the pattern of carriers distributed in the frame, the type of modulation, the coding rate. The lack of opportunities to choose the optimal parameters in each of the regions, in aggregate, leads to problems of ensuring the necessary stability margins for the operation of SFN networks, estimated by the bit error rate, which can lead to disruption of the normal operation of networks (technical stops and technical rejects) and underutilization of the transmission speed capabilities of the networks being created. information.

Recently, the term "SCTE tags" has been used more and more often in the everyday life of television specialists. But not everyone is completely familiar with what these are notes, how they work and what they are used for. To clarify, SkyLark Technology contacted Alexander Peregudov, a well-known industry expert, who specially prepared an article on this topic for Mediavision magazine. The first part of the article is published below.

Network broadcasting systems architecture with digital program insertion

The fundamental principles and technological solutions for the use of SCTE-104/35 labels (messages) were developed by the American Society of Cable Television Engineers (SCTE). The initial purpose of using SCTE-104/35 tags is to control digital program insertion - DPI (Digital Program Insertion) - in TV broadcasting networks that relay the signal from the central station through digital broadcasting channels of MPEG-2 TS transport streams. The term Digital Ad Insertion is also used.

As technologies develop and the set of functions expands, the ideology of SCTE tags is constantly being improved and reflected in new standards and recommendations. These documents are freely available at www.scte.org. SCTE does not impose any restrictions or financial obligations on broadcast TV networks intending to use these digital ad insertion management methods.

This factor plays an important role in the constant development of TV technologies and the emergence of new solutions, equipment and systems. SCTE-104/35 specifications allow managing not only ad insertion, but also other procedures for modifying content in distributed TV systems, including banner and targeted advertising. SCTE-104/35 technology is also used in the distribution channels of video-on-demand programs over HTTP, including Adobe Dynamic Streaming (HDS), Apple Live Streaming (HLS), Microsoft Smooth Streaming (MSS), MPEG-DASH.

Linear network broadcasting

The linear network broadcasting model is based on the regional retransmission of the program signal generated by the network central station (Figure 1-1).

Figure 1-1. DPI-enabled broadcast system architecture

The central station program signal is generated at the program generation center (PSC). In the English language literature, the term Broadcast Operation Center (BOC) is used.

The HD / SD-SDI interface is usually used to transfer the program signal to the compression system. Here, video and audio signals are compressed and multiplexed into an MPEG-2 TS of one program (Single Program Transport Stream - SPTS). SPTS, in turn, can be multiplexed into a Multi Program Transport Stream (MPTS). The term Network Operation Center (NOC) is used for advanced multi-program compression systems.

SPTS or MPTS streams are transmitted via DVB or IP interfaces to Regional Program Relay Centers (RPC), where they are modified by inserting regional content and then retransmitted to their broadcasting territory in the form of modified SPTS or MPTS streams. In fig. 1-1 shows the path of SCTE-104/35 messages from the source (DSP) to the final destination - the splicer-server bundle as part of the DSP.

Slots

Insertions of regional content must occur at designated time slots in the broadcasting schedule of the central station. These time slots are called avails in SCTE documents. When translated into Russian, the terms "commercial time interval", "regional advertising window", "advertising time slot" and other variants are used. In what follows, the term "slot" will be used as an analogue of avail.

At the slot boundaries, switching, or splicing, is performed between signals from the main channel (signal from the central station) and from the input channel (signal from the regional station). The center / region switching point is called the Splice In Point, the region / center switching point is called the Splice Out Point.

Splicer functions

Switching signals in the digital control center is performed by a splicer (Splicer). DPI specifications define seamless - imperceptible to the viewer in image and sound - frame-accurate splicing.

In DPI systems, the interval of time of insertion (break) is usually considered as one event of replacement of a program fragment in the signal of the central station with an equal or close advertising block from the signal of the regional station. The ad unit includes separate ad clips.

The splicer receives the traffic flow from the central station through the main channel and the traffic flow from the advertising server through the input channel. At the time of the entry point, the splicer switches the input channel from the ad server to the output channel. At the time of the exit splicing point, reverse switching occurs.

Ad server functions

The ad server within the CRP is responsible for playing one or more files that make up the regional break. The insertion of a regional break from the input channel into the main channel occurs within a single session, during which the splicer and the advertising server synchronize their work via a TCP / IP connection in the local network of the CRP. The SCTE 30 specification describes standardized protocols for the interaction of the splicer and the ad server.

Seamless splicing conditions

Frame-accurate seamless splicing between MPEG-2 TS streams from central and regional stations requires several conditions.

First, the transport stream from the hub at the splicing points in MPEG-2 encoding must start with a closed GOP with an I-frame at the beginning of the group and I- or P-type frames in it. When encoding H.264 / AVC or H.265 / HEVC at splicing points, a closed group must begin with an IDR (Instantaneous Decoder Refresh) frame and end with an I or P frame. The decoder's reception of an IDR frame means that decoding after the splicing point can be performed without using the preceding frames. For Variable Bit Rate (VBR) encoding, it is recommended to switch to Constant Bit Rate (CBR) encoding in the slot interval. The condition is provided by the encoder as part of the compression system in response to receiving the SCTE-104 control message from the automation system.

Secondly, the transport stream reproduced from the files by the advertising server must be formed according to the same rules regarding the formation of the GOP structure. The parameters of the image and sound, the speed of the generated stream must be the same as that of the stream from the central station. The condition is ensured by proper compression of the ad break files.

Thirdly, the splicer must receive a message about splicing points from the automation system in advance, send a command to the advertising server to start the required break, and perform splicing at the inlet and outlet points. The condition is provided by the transmission of the SCTE-104/35 control message from the automation system to the address of the splicer.

And, fourthly, the ad server must start playing the regional break files at a certain time before the start of the replacement, and end it after the regional break with the condition that the start and end points of the break during playback coincide with the moment of channel switching in the splicer.

SCTE-104/35 Messages

The DPI implementation according to SCTE-104/35 specifications is based on the transmission of cueing messages about upcoming slots for inserting regional breaks. The term cueing message, when translated into Russian, is equally interpreted as "a message with the SCTE-104/35 tag" or as "the SCTE-104/35 tag". The term cueing message evolved from previous specifications for managing analogue ad insertion using DTMF (Dual Tone Multi-Frequency signaling), called analog cue tone. Therefore, sometimes the term digital cue tone is used instead of cueing message.

SCTE-104/35 messages about the upcoming splicing event are generated by the automation system, which is part of the FSC. As part of the message, among other data, the slot start / end time and slot identifiers are transmitted, allowing each slot to be associated with the required regional content.

Then these messages are sent to the address of the encoder and multiplexer as part of the compression system, as well as to the address of the splicer as part of the digital control center. The splicer relays the content of the message to the ad server, controlling its operation.

It should be noted that the use of SCTE-104/35 messages does not guarantee seamless splicing under all possible conditions, but ensures the frame accuracy of signaling about planned signal source switching events in the DRC.

SCTE-104/35 message transmission channels

The message with splicing data is transmitted through the chain "automation system - compression system - splicer", which consists of two segments.

The compression-splicer segment uses the MPEG-2 TS transmission channel. Here, the Splice Information Table is transmitted in SCTE-35 messages as the Splice_info_section bit sequence. SCTE-35 messages are generated by the SCTE-35 injector as a separate elementary private PID data stream, which is multiplexed into a common SPTS output stream together with video / audio PID streams linked to a single Presentation Time Stamps (PTS) timeline. The SCTE-35 PID stream identifier is declared in the Program Map Table (PMT) as an integral part of the program as part of a single-program (SPTS) or multi-program (MPTS) MPEG-2 TS transport stream. To transmit SCTE-35 messages, the bandwidth of the MPEG-2 TS channel must have several kbps in addition to the total rate of video / audio and other data streams. Equipment that changes the composition of programs or the speed of its constituent elementary video / audio streams should not change the binding of the SCTE-35 stream to the program or break its connection with the PTS timestamps.

The segment “automation system - compression system” can use two types of transmission channels. The first option is a loopback channel over a TCP / IP connection, the second option is an open loop channel over the SDI interface. In both cases, the Splice Information Table data in this segment is formatted as SCTE-104 messages (requests). The rules for sending and receiving SCTE-104 messages, as well as the data storage in them, are standardized by the SCTE 104 document in the form of an application programming interface (API).

Both types of messages are used for sequential transmission of splicing data from the automation system to the splicer, hence the term SCTE-104/35 messages.

SCTE-104 message transmission channel with feedback

The bi-directional communication channel between the automation system and the injector (Fig. 1-2) allows the injector and the encoder to confirm the receipt and processing of SCTE-104 messages received from the automation system.

Figure 1-2. Formation of SCTE-104 messages in a channel with feedback

There are undoubted advantages in this solution, but there are also implementation problems. SCTE-104/35 messages contain data in binary form. Text data like XML tags are not transmitted in SCTE-104/35 messages. This limitation significantly reduces the amount of data transferred and the bandwidth requirements of the transmission channel. On the other hand, the binary representation of data in SCTE-104 messages places special demands on the TCP / IP network linking automation and compression systems. It should be a strictly private network, in which the guaranteed message transmission delay time should be significantly less than the duration of the TV frame. It is recommended to use the standard port (socket) number for communication - 5167.

In most versions of such a channel, the DPC and the compression system are located at a considerable distance from each other and are controlled by different operators, which introduces the technical difficulties of creating a reliable TCP / IP connection between them via VPN (Virtual Private Network) networks.

SCTE-104 message transmission channel without feedback

The unidirectional SDI interface is an obligatory communication channel between the DFP and the compression system, and therefore it is logical to use it to transmit SCTE-104 messages. It is accepted to transmit SCTE-104 messages as additional data in the VANC interval (Vertical ANCillary) of the SDI signal according to the SMPTE 291M standard. The details of mapping SCTE-104 message data into VANC packets are regulated in SMPTE RP2010. The ANC type 2 packets are used, where the payload identifier (ID) of the packet is a pair of Data ID (DID) and Secondary Data ID (SDID). DID \u003d 41h and SDID \u003d 07h for VANC packets indicate that SCTE-104 is sent in these packets.

The VANC packet with SCTE-104 message data, in principle, can be placed on any line outside the active part of the frame. However, it is recommended to place the VANC data in the Y channel data stream on the second line after the Switch point defined in SMPTE recommendation RP168. In most cases, the 12th line of the first field is used for all SD / HD-SDI decomposition standards.

In fig. 1-3 shows the SCTE-104 unidirectional data transmission channel from the automation system to the injector and encoder as part of the compression system through an additional device called the SCTE-104 inserter. SCTE 104 uses the term Proxy Device to refer to an inserter, and SMPTE RP2010 uses the term inserter.

Figure 1-3. Formation of SCTE-104 messages in a channel without feedback

The job of the inserter is to encapsulate the SCTE-104 message into an SDI signal. The inserter is controlled from the automation system, has SDI inputs / outputs, and a broadcast program signal is input. SCTE-104 defines a standard API for managing the inserter from the automation system over the TCP / IP network to the FSC.

SCTE-104 messages formed by the inserter as part of the SDI signal are transmitted from the automation system to the next in-stream device to the final destination - the injector as part of the compression system. In this mode, the automation system operates without feedback messages from the compression system, on the principle of the best possible operation. For example, messages can be sent multiple times, duplicating the notification of the same splicing operation.

On the side of the compression system, splicing data from the SCTE-104 message is transferred to the SCTE-35 message using the SCTE-35 injector.

In this scheme, the SCTE-104 / SDI unidirectional transmission channel operates between the automation system and the injector. At the same time, between the automation system and the inserter, its own interaction is organized, which can also be bidirectional when using a TCP / IP or RS-422 connection, or unidirectional when controlling the inserter through GPI contacts. The first option is preferable, which is quite simple to implement, since the automation system and the inserter are part of the same DFP.

The lack of feedback between the automation system and the injector is compensated by the relative simplicity of constructing the SCTE-104 message delivery path based on standard hardware components with SDI interfaces. Equipment that does not change the content of the SDI signal (switches, distributors) almost always passes VANC data. Devices that change the content of the SDI signal (delay, signal mixing) must correctly pass VANC data from input to output. When the signal passes correctly through the HD / SD-SDI paths, SCTE-104 tags remain anchored to the frame in which they were originally inserted.

Keywords

STANDARD DVB-T2 / MULTIPLEX / FEDERAL TARGET PROGRAM / REGIONAL CONTENT / TRUNK NETWORK / REGIONAL NETWORK / REPLAYER / SFN / SYNCHRONIZATION / PROTECTION INTERVAL / MODULATION / CODING

annotation scientific article on electrical engineering, electronic engineering, information technology, the author of the scientific work - Karjakin Vladimir Leonidovich, Karjakin Dmitry Vladimirovich, Morozova Lyudmila Aleksandrovna

The analysis of methods for organizing broadcasting of the First multiplex in the DVB-T2 standard with an insert regional content in various versions of the construction of single-frequency SFN networks of digital terrestrial broadcasting of the Russian Federation. The problems of import substitution of the technology of distributed modification of programs using a replayer are noted, since Enensys Technologies owns a Russian patent for a DVB-T2 broadcasting method with an insert regional content and the device used in this method. The disadvantage of the technical solutions used in the Russian Federation to implement the task of delivering the regional version of the First multiplex is the need to broadcast combined T2-MI streams in different regions with uniform parameters set in the federal multiplexing center (FCFM). The uniform parameters set in the FCFM lead to a number of problems associated with different broadcasting conditions by the territorial location of transmitters, by the type and intensity of interference, as well as by different climatic and geographical conditions of broadcasting on the territory of the Russian Federation. The DVB-T2 broadcasting standard allows providing a wide range of parameters for the created SFN networks for their adaptation to the working conditions. Choice is needed guard interval for a specific topology of transmitter placement. To ensure synchronous operation of transmitters of a single-frequency network, a time stamp is set based on the resulting time delays of the information signal. The type and intensity of interference, geographical conditions of broadcasting depend on the choice of the pattern of carriers distributed in the frame, the type of modulation, the coding rate. The lack of opportunities to choose the optimal parameters in each of the regions, in aggregate, leads to problems of ensuring the necessary stability margins for the operation of SFN networks, estimated by the bit error rate, which can lead to disruption of the normal operation of networks (technical stops and technical rejects) and underutilization of the transmission speed capabilities of the networks being created. information.

Text of scientific work on the topic "Methods of TV broadcasting in the DVB-T2 standard with the insertion of regional content"

TV BROADCASTING METHODS IN DVB-T2 STANDARD WITH INSERTING REGIONAL CONTENT

Karjakin Vladimir Leonidovich,

doctor of Technical Sciences, Professor of the Department of Radio Communication, Radio Broadcasting and Television, Volga State University of Telecommunications and Informatics (PSUTI), Samara, Russia, [email protected]

Dmitry Karyakin,

ph.D., Senior Systems Engineer, Russian representative office of Juniper Networks, Moscow, Russia, [email protected]

Morozova Lyudmila Alexandrovna,

candidate of Technical Sciences, Associate Professor of the Department of Economics and Organization of Production of PSUTI, Samara, Russia, [email protected]

Keywords: DVB-T2 standard, multiplex, federal target program, regional content, backbone network, regional network, replayer, SFN network, synchronization, guard interval, modulation, coding.

For citation:

Karjakin V.L., Karjakin D.V., Morozova L.A. TV broadcasting methods in the DVB-T2 standard with the insertion of regional content // T-Comm: Telecommunications and transport. - 2016. - Volume 10. - No. 4. - S. 41-46.

Karyakin V.L., Karyakin D.V., Morozova L.A. Methods of TV broadcasting in the standard DVB-T2 with inserts regional content. T-Comm. 2016. Vol. 10.No.4, pp. 41-46. (in Russian)

1. Introduction

The digital terrestrial television and radio broadcasting network of the Russian Federation in the DVB-T2 standard is intended to cover the population of the Russian Federation by digital hanging of the teleradi package about the programs of the first multiplex in accordance with the Federal Target Program.

The list and sequence of TV and radio programs included in the first multiplex is determined by the Decree of the President of the Russian Federation, while the obligatory public TV programs included in the first multiplex are subject to modification in each of the regions in accordance with the requirements of broadcasting organizations.

The issue of choosing the architecture of the digital broadcasting distribution network is of particular importance, since the choice of the version of this architecture directly depends on the scheme for constructing single-frequency SFN (Single Frequency Network) digital broadcasting networks in each of the regions, the quality and cost of communication services provided by FGU11 Russian Television and broadcasting network ”(RTRS) to broadcasters.

One of the important criteria for the quality of communication services is the likelihood of technical defects and technical stops, i.e. the likelihood of disruptions to the normal operation of the digital television broadcasting network. A necessary condition for the high quality of digital radio and television broadcasting services is to provide a certain margin of stability for SFN networks in terms of the number of bit errors when receiving programs of the First multiplex in the service area.

In contrast to DVB-T, the DVB-T2 broadcasting standard has greater flexibility in the created single-frequency SFN networks and has a number of features that allow for more efficient regional modification of television and radio programs, especially when using satellite delivery of signals to transmitting stations.

The purpose of this work is to analyze the methods of organizing the broadcasting of the First multiplex in the DVB-T2 standard with the insertion of regional content in various options for building a digital terrestrial broadcasting network in the Russian Federation.

The digital terrestrial hanging network of the Russian Federation consists of 82 regional networks, in the center of each of which there is a regional center for the formation of multiplexes (RCFM).

The federal version of the first multiplex and its temporary duplicates to provide broadcasting in 5 broadcasting zones of the Russian Federation L, B, V, G and M should be delivered to all RCFMs via satellite communication lines. Signal transmission of the First multiplex via satellite communication lines is encrypted.

To compare various options for building a network, it is assumed that in each region, with the exception of Moscow, the Moscow region, Sapkg-Petersburg and the Leningrad region, three TV and radio channels will be modified: "Russia 1", "Radio Russia" and "Russia 24",

2. Composition of the network software substitution system

digital terrestrial television and radio broadcasting of the Russian

Federation of DVB-T2 standard

The system of program substitution of the digital terrestrial television and radio broadcasting network of the DVB-T2 standard has a structure.

consisting of the federal complex of program substitution (FKPZ) and the regional complex of program substitution (RKPZ).

The FKPZ (Fig. 1) includes not only the equipment of the federal center for the formation of multiplexes (FTSFM), but also part of the equipment of federal broadcasting companies, in particular, the equipment of the hardware-studio complex (ASK), which generates controllers for the replacement system.

dec ■ y l- * FCFM

; f Channels \\ Delivery)

Federal broadcaster 1 i Federal broadcaster 2 \\ Federal broadcaster N:

Figure: I. Scheme of the federal complex and program substitution

The regional complex of software replacement includes the equipment of the regional center for the formation of the RCFM multiplex and the equipment of the ASK of regional broadcasting companies. In addition, the RKPZ may include additional equipment located directly at the radio and television transmitting stations (RTPS) of a given region, in particular, equipment for inserting regional content - a replayer (Fig. 2).

ASK c RCFM

G Channels \\

Regional broadcaster i | fc-nI dmtvvki)

: Regional hanger 2

| Repin “alny broadcaster NÎ

Figure: 2. Scheme of the regional complex of program substitution

3. Schemes for building a digital terrestrial broadcasting network

A generalized diagram of the distribution network of the first multiplex is shown in Fig. 3.

The following abbreviations have been introduced here: FCFM - federal center for the formation of a multiplex; RCFM - regional center for the formation of the multiplex; FASK - federal hardware-studio complex; PACK - regional hardware-studio complex; FNMS - federal ground backbone network; RNRS - regional land distribution network; MZSSS - satellite communication peripheral earth station; Remote control DVB-S2 -transmitter of the DVB-S2 standard; Remote control DVB-T2 - transmitting device of DVB-T2 standard; PrU is a DVB-T2 standard receiver.

Various options for the formation of a regional version of the First TV and Radio Broadcasting Multiplex are considered below and a comparative analysis of these options from the point of view of technical and financial resources that will require the implementation of each of them is carried out.

T-Comm Volume 10. # 4-2016

T-Sott Volume 10. # 4-2016

The use of this option was not envisaged by the system projects for the digital terrestrial broadcasting network a peí ions of the Russian Federation, however, it is currently recommended)

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