1、 ETSI TS 102 772 V1.1.1 (2010-09)Technical Specification Digital Video Broadcasting (DVB);Specification of Multi-Protocol Encapsulation - inter-burstForward Error Correction (MPE-iFEC)ETSI ETSI TS 102 772 V1.1.1 (2010-09)2Reference DTS/JTC-DVB-244 Keywords broadcasting, data, digital, DVB, IP, mobil
2、e, TV, video ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N 348 623 562 00017 - NAF 742 C Association but non lucratif enregistre la Sous-Prfecture de Grasse (06) N 7803/88 Important notice Individual copies of the present d
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6、ritten permission. The copyright and the foregoing restriction extend to reproduction in all media. European Telecommunications Standards Institute 2010. European Broadcasting Union 2010. All rights reserved. DECTTM, PLUGTESTSTM, UMTSTM, TIPHONTM, the TIPHON logo and the ETSI logo are Trade Marks of
7、 ETSI registered for the benefit of its Members. 3GPPTM is a Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. LTE is a Trade Mark of ETSI currently being registered for the benefit of its Members and of the 3GPP Organizational Partners. GSM and th
8、e GSM logo are Trade Marks registered and owned by the GSM Association. ETSI ETSI TS 102 772 V1.1.1 (2010-09)3Contents Intellectual Property Rights 5g3Foreword . 5g3Introduction 5g31 Scope 8g32 References 8g32.1 Normative references . 8g32.2 Informative references 9g33 Definitions, symbols and abbre
9、viations . 9g33.1 Definitions 9g33.2 Symbols 11g33.3 Abbreviations . 12g34 Sender operation . 12g34.1 Introduction 12g34.2 Parameters 13g34.3 Initialization . 14g34.4 Reception of New Datagram Burst . 14g34.5 Generation of IFEC-Burst 15g34.6 Time-Slice Burst Generation and Sending . 16g34.7 Datagram
10、 Burst to ADT Mapping 16g34.8 Generation of iFDT 16g35 Carriage of MPE-IFEC sections (normative) . 17g35.1 Generalities. 17g35.2 Syntax and semantics . 17g35.3 Real time parameters 18g36 Time Slice and FEC identifier descriptor (normative) . 19g36.1 Introduction (informative) 19g36.2 Descriptor (nor
11、mative) . 19g36.3 Sliding Encoding with RS code (normative) 23g36.3.1 General 23g36.3.2 Parameter Definitions . 23g36.3.3 Mapping Functions . 24g36.3.4 Generation of iFDT . 24g36.3.5 Memory considerations . 24g36.4 Generalized Encoding with Raptor code (informative) 24g36.4.1 General 24g36.4.2 Param
12、eter Definitions . 24g36.4.3 Mapping Functions . 25g36.4.4 Generation of iFDT . 25g36.4.5 Example Parameters . 25g3Annex A (informative): Receiver operation . 27g3A.1 Introduction 27g3A.2 General Process 27g3A.3 Parameters 28g3A.4 Burst number detection 28g3A.5 Section Reception . 30g3A.6 Padding in
13、 ADST mapping 30g3A.7 Decoding 31g3ETSI ETSI TS 102 772 V1.1.1 (2010-09)4A.7.1 Input . 31g3A.7.2 RS decoding . 31g3A.7.3 Raptor decoding . 32g3A.7.4 Output . 32g3History 33g3ETSI ETSI TS 102 772 V1.1.1 (2010-09)5Intellectual Property Rights IPRs essential or potentially essential to the present docu
14、ment may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found in ETSI SR 000 314: “Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of
15、 ETSI standards“, which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web server (http:/webapp.etsi.org/IPR/home.asp). Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to the exist
16、ence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present document. Foreword This Technical Specification (TS) has been produced by Joint Technical Committee (JTC) Broadcast of the European Broadcasting
17、Union (EBU), Comit Europen de Normalisation ELECtrotechnique (CENELEC) and the European Telecommunications Standards Institute (ETSI). NOTE: The EBU/ETSI JTC Broadcast was established in 1990 to co-ordinate the drafting of standards in the specific field of broadcasting and related fields. Since 199
18、5 the JTC Broadcast became a tripartite body by including in the Memorandum of Understanding also CENELEC, which is responsible for the standardization of radio and television receivers. The EBU is a professional association of broadcasting organizations whose work includes the co-ordination of its
19、members activities in the technical, legal, programme-making and programme-exchange domains. The EBU has active members in about 60 countries in the European broadcasting area; its headquarters is in Geneva. European Broadcasting Union CH-1218 GRAND SACONNEX (Geneva) Switzerland Tel: +41 22 717 21 1
20、1 Fax: +41 22 717 24 81 The Digital Video Broadcasting Project (DVB) is an industry-led consortium of broadcasters, manufacturers, network operators, software developers, regulatory bodies, content owners and others committed to designing global standards for the delivery of digital television and d
21、ata services. DVB fosters market driven solutions that meet the needs and economic circumstances of broadcast industry stakeholders and consumers. DVB standards cover all aspects of digital television from transmission through interfacing, conditional access and interactivity for digital video, audi
22、o and data. The consortium came together in 1993 to provide global standardisation, interoperability and future proof specifications. Introduction MPE-IFEC is introduced to support reception in situations of long duration erasure on the MPE section level spanning several consecutive time slice burst
23、s. Such erasure situations may for example occur on LMS channels without any terrestrial repeaters in the vicinity: obstacles may hinder direct satellite reception and induce losses of several successive bursts. For example, with an MPE-IFEC protection where about 30 % of TS data are allocated to pa
24、rity overhead computed over 10 successive bursts, it is possible to compensate up to 3 successive complete burst losses whereas recovery of a complete burst loss with DVB-H MPE-FEC protection would not be possible. Such erasure situation may also occur in terrestrial networks so that MPE-IFEC may be
25、 useful in other channels than LMS. ETSI ETSI TS 102 772 V1.1.1 (2010-09)6The MPE-IFEC protection is computed over several successive datagram bursts, as opposed to MPE-FEC where the computation is performed on a single datagram burst. This multi-burst protection is enabled by an enlargement of the
26、encoding matrix to sizes greater than one burst (an IFEC matrix is filled not by one burst as in MPE-FEC but by several successive bursts), by a parallelization of the encoding mechanism (instead of using only one matrix, the data are distributed to a number of parallel matrices equal to B) or by a
27、combination of both principles. The datagrams themselves are sent in MPE sections without any modification compared to EN 301 192 1, clause 9.6. The resulting parity may also be spread over several bursts instead of one single burst in the MPE-FEC case: each burst contains parity coming from S matri
28、ces. An overview of the link layer operations, especially the MPE-IFEC, in the case of DVB-SH is presented in figure 1. Datagram bursts of variable size (in terms of number of bytes and/or number of datagrams) are used as input and mapped by an ADST function on to the ADTs of up to M parallel encodi
29、ng matrices. The IFEC burst collects all MPE-IFEC sections from iFDTs of several encoding matrices. An MPE-IFEC section is comprised of a header, the data from multiple columns from the same iFDT, and a checksum. This IFEC burst is then merged with all MPE sections of an original datagram burst, inc
30、luding its MPE-FEC if present, to generate the time slice burst that is actually sent over the air. This merging is done with the datagram just received when the delay parameter D is set to D=0, or with a previously received datagram when D0. Note that the original data in MPE sections fully complie
31、s with EN 301 192 1, clause 9.6. This multi-burst parity computation and spreading is achieved at the expense of some latency for generating and receiving parity data. Nevertheless, as datagram bursts are sent unmodified, many well-known receiver operations are still possible. For example, the recei
32、ved MPE sections may be immediately forwarded to media decoders for fast channel-switching (zapping) support. Only when the parity is needed, the forwarding should be delayed to accumulate sufficient redundancy information. Datagram Burst k-DDatagram Burst k-1Datagram Burst kDatagram Burst kADT m AD
33、T M-1ADT 0IFEC Burst kBurst Generation and Time SlicingMPE-FEC (if used)Datagram Burst k-DEncodingiFDT m iFDT M-1Sections coming from S iFDTare interleaved inside the iFEC burst kiFDT 0Each ADST is split in B parts,each being placed in one ADTADSTMPE-IFEC ProcessEncodingEncodingDatagramBurst sizeEve
34、ry EP datagram bursts,encoding is calculated for the the current ADTsSEP datagramsburstsDatagram Burst k-DBFigure 1: MPE-IFEC encoding process ETSI ETSI TS 102 772 V1.1.1 (2010-09)7The MPE-IFEC is introduced in such a way that MPE-IFEC ignorant (but MPE and MPE-FEC capable) DVB receivers will be abl
35、e to extract the MPE stream in a fully backwards-compatible way. This backwards compatibility holds both when the MPE-IFEC is used with and without Time Slicing. The use of MPE-IFEC is not mandatory and is defined separately for each elementary stream in the transport stream. For each elementary str
36、eam it is possible to choose whether or not MPE-IFEC is used, and if it is used, to choose the trade-off between IFEC overhead, extra delay and performance. Time critical services, without MPE-IFEC and therefore minimal delay, could therefore be transmitted together with less time critical services
37、using MPE-IFEC, on the same transport stream but on different elementary streams. ETSI ETSI TS 102 772 V1.1.1 (2010-09)81 Scope The present document specifies a protection scheme for the MPE sections specifically adapted for broadcasting environments supporting long duration fadings such as DVB-SH.
38、Clause 3 introduces the (normative) definitions, symbols and abbreviations. Clause 4 introduces the (normative) sender operation. The present document specifies a generic framework that exhibits enough flexibility for a variety of applications, some of which are mandated for a usage in DVB-SH in the
39、 “framework mapping“ in clause 6. Clause 5 describes the (normative) carriage of MPE-IFEC sections. Clause 6 provides (normative) syntax of Time Slice and FEC identifier descriptor. Two mapping of the generic framework are given: - One based on MPE-FEC Reed Solomon code (EN 301 192 1, clause 9.5.1)
40、and called “sliding RS encoding“ is normative. - Another based on Raptor code (TS 102 472 2) and called “generalized encoding with Raptor code“ is informative. Annex A introduces (informative) prototype IFEC decoding. NOTE: The present document is intended to be ultimately added as an annex to EN 30
41、1 192 1 but can be used independently as it is natively self-contained. 2 References References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the l
42、atest version of the reference document (including any amendments) applies. Referenced documents which are not found to be publicly available in the expected location might be found at http:/docbox.etsi.org/Reference. NOTE: While any hyperlinks included in this clause were valid at the time of publi
43、cation ETSI cannot guarantee their long term validity. 2.1 Normative references The following referenced documents are necessary for the application of the present document. 1 ETSI EN 301 192 (V1.4.1): “Digital Video Broadcasting (DVB); DVB Specification for Data Broadcasting“. 2 ETSI TS 102 472 (V1
44、.2.1): “Digital Video Broadcasting (DVB); IP Datacast over DVB-H: Content Delivery Protocols“. 3 ETSI TS 102 584 (V1.1.1): “Digital Video Broadcasting (DVB); DVB-SH Implementation Guidelines“. 4 ISO/IEC 13818-6: “Information technology - Generic coding of moving pictures and associated audio informa
45、tion - Part 6: Extensions for DSM-CC“. 5 ISO/IEC 13818-1: “Information technology - Generic coding of moving pictures and associated audio information: Systems“. ETSI ETSI TS 102 772 V1.1.1 (2010-09)92.2 Informative references The following referenced documents are not necessary for the application
46、of the present document but they assist the user with regard to a particular subject area. Not applicable. 3 Definitions, symbols and abbreviations 3.1 Definitions For the purposes of the present document, the following terms and definitions apply: Application Data Sub Table (ADST): function used to
47、 map IP datagrams in Application Data Tables (ADTs) NOTE: The Application Data Sub Table (ADST) is a function that allows mapping of a datagram burst to an ADT: ADST(j) refers to the jthcolumn of the result of the mapping of the datagram burst on an intermediate matrix of C columns and T rows whereb
48、y j=0,1, C-1. Mapping of a datagram burst with Layer 3 datagrams on such a C*T matrix is shown in figure 2: the leftmost columns of the matrix host all datagrams of a datagram burst. The remaining columns are filled with possible padding. The first datagram in the datagram burst starts with its firs
49、t byte in the upper left corner of the matrix and goes downwards to the first column. The length of the datagrams MAY vary arbitrarily from datagram to datagram. Immediately after the end of one datagram the following datagram starts. If a datagram does not end precisely at the end of a column, it continues at the top of the following column. When all datagrams have entered the matrix, any unfilled byte positions are padded with zero bytes, making all columns completely filled. After the mapping, each position in the matrix hosts an inform
