1、 ETSI TS 102 542-3-2 V2.1.1 (2016-04) Digital Video Broadcasting (DVB); Guidelines for the implementation of DVB-IPTV Phase 1 specifications; Part 3: Error Recovery; Sub-part 2: Application Layer - Forward Error Correction (AL-FEC) TECHNICAL SPECIFICATION ETSI ETSI TS 102 542-3-2 V2.1.1 (2016-04) 2
2、Reference RTS/JTC-DVB-360-3-2 Keywords broadcasting, digital, DVB, IP, 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 Grass
3、e (06) N 7803/88 Important notice The present document can be downloaded from: http:/www.etsi.org/standards-search The present document may be made available in electronic versions and/or in print. The content of any electronic and/or print versions of the present document shall not be modified with
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5、he present document should be aware that the document may be subject to revision or change of status. Information on the current status of this and other ETSI documents is available at https:/portal.etsi.org/TB/ETSIDeliverableStatus.aspx If you find errors in the present document, please send your c
6、omment to one of the following services: https:/portal.etsi.org/People/CommiteeSupportStaff.aspx Copyright Notification No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm except as authorized by written permission of ETSI
7、. The content of the PDF version shall not be modified without the written authorization of ETSI. The copyright and the foregoing restriction extend to reproduction in all media. European Telecommunications Standards Institute 2016. European Broadcasting Union 2016. All rights reserved. DECTTM, PLUG
8、TESTSTM, UMTSTMand the ETSI logo are Trade Marks of ETSI registered for the benefit of its Members. 3GPPTM and LTE are Trade Marks of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. GSM and the GSM logo are Trade Marks registered and owned by the GSM Associati
9、on. ETSI ETSI TS 102 542-3-2 V2.1.1 (2016-04) 3 Contents Intellectual Property Rights 5g3Foreword . 5g3Modal verbs terminology 5g31 Scope 6g32 References 6g32.1 Normative references . 6g32.2 Informative references 6g33 Abbreviations . 7g34 Overview of DVB AL-FEC implementation guidelines 7g35 Config
10、uring FEC protection . 8g35.0 General Preparations 8g35.1 Correcting for burst losses 8g35.2 Correcting for random losses 8g36 FEC sending arrangement considerations 9g36.1 Introduction 9g36.2 Client considerations 9g36.3 FEC Sending Arrangements . 10g36.3.0 General 10g36.3.1 Constant rate, non-inte
11、rleaved sending . 10g36.3.2 Fully interleaved sending 11g36.3.3 Partially interleaved sending . 11g36.3.4 Faststart sending for stored/buffered content 12g37 Layered multicast sending 12g38 Criterion for selection of Forward Error Correction for the protection of audiovisual streams delivered over I
12、P Network Infrastructure . 13g38.1 Requirements 13g38.2 System description . 14g38.3 Packet loss characteristics 14g38.4 FEC Scheme Evaluation Criteria 15g39 AL-FEC evaluation report for DVB-TM IPI 16g39.0 General . 16g39.1 Introduction 16g39.2 Sending arrangement considerations 16g39.3 Bandwidth co
13、sts . 17g39.3.0 Objectives . 17g39.3.1 Loss models 17g39.3.2 Multicast case . 17g39.3.2.0 Simulation results 17g39.3.2.1 Results with constant sending arrangement 18g39.3.2.2 Results with burst sending arrangement 19g39.3.3 Unicast case 22g39.3.3.1 Stored/buffered content . 22g39.3.3.2 Live content.
14、 24g39.3.3.2.0 Simulation results for unicast delivery 24g39.3.3.2.1 Constant sending arrangement . 25g39.3.3.2.2 Burst sending . 26g39.3.4 A note on latency, jitter and traffic shaping 29g39.3.5 Summary of simulation results . 30g39.4 Flexibility . 31g39.5 Processing and Memory requirements . 31g39
15、.6 Additional criteria. 32g39.7 Content Download 33g3ETSI ETSI TS 102 542-3-2 V2.1.1 (2016-04) 4 9.8 Raptor vs. Pro-MPEG Summary 33g39.9 Conclusions 34g310 Sending arrangements used for simulations . 35g310.1 DF Raptor default sending arrangement . 35g310.2 Pro-MPEG COP3 fully interleaved sending ar
16、rangement 36g310.3 Pro-MPEG COP3 burst sending arrangement 36g310.4 Concurrent Interleaved sending 37g310.5 DF Raptor faststart sending for stored/buffered content . 38g311 Concurrent interleaving results 39g312 Hybrid code 43g312.0 General . 43g312.1 Hybrid code results . 44g3History 48g3ETSI ETSI
17、TS 102 542-3-2 V2.1.1 (2016-04) 5 Intellectual Property Rights IPRs essential or potentially essential to the present document 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
18、SR 000 314: “Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards“, which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web server (https:/ipr.etsi.org/). Pursuant to the ETSI IPR Policy, no in
19、vestigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence 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 Spe
20、cification (TS) has been produced by Joint Technical Committee (JTC) Broadcast of the European Broadcasting 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
21、to co-ordinate the drafting of standards in the specific field of broadcasting and related fields. Since 1995 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 E
22、BU is a professional association of broadcasting organizations whose work includes the co-ordination of its 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 headquarter
23、s is in Geneva. European Broadcasting Union CH-1218 GRAND SACONNEX (Geneva) Switzerland Tel: +41 22 717 21 11 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, co
24、ntent owners and others committed to designing global standards for the delivery of digital television and data 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 te
25、levision from transmission through interfacing, conditional access and interactivity for digital video, audio and data. The consortium came together in 1993 to provide global standardization, interoperability and future proof specifications. The present document is part 3, sub-part 2 of a multi-part
26、 deliverable. Full details of the entire series can be found in part 1 i.1. Modal verbs terminology In the present document “shall“, “shall not“, “should“, “should not“, “may“, “need not“, “will“, “will not“, “can“ and “cannot“ are to be interpreted as described in clause 3.2 of the ETSI Drafting Ru
27、les (Verbal forms for the expression of provisions). “must“ and “must not“ are NOT allowed in ETSI deliverables except when used in direct citation. ETSI ETSI TS 102 542-3-2 V2.1.1 (2016-04) 6 1 Scope The present document is designed as a companion document to help implement the DVB-IPTV Phase 1 spe
28、cification ETSI TS 102 034 1, which is referred to as the Handbook. Part 3 of this multi-part deliverable deals with Error recovery technologies i.2 and i.3. The present document provides guidelines on the Application Layer - Forward Error Correction (AL-FEC) technology. 2 References 2.1 Normative r
29、eferences 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 latest version of the referenced document (including any amendments) applies
30、. 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 publication, ETSI cannot guarantee their long term validity. The following refe
31、renced documents are necessary for the application of the present document. 1 ETSI TS 102 034: “Digital Video Broadcasting (DVB); Transport of MPEG-2 TS Based DVB Services over IP Based Networks“. 2 ETSI TS 126 346: “Universal Mobile Telecommunications System (UMTS); Multimedia Broadcast/Multicast S
32、ervice (MBMS); Protocols and codecs (3GPP TS 26.346 Release 7)“. 3 SMPTE Specification 2022-1 (2007): “Forward Error Correction for Real-time Video/Audio Transport Over IP Networks“. 4 ETSI TS 102 005: “Digital Video Broadcasting (DVB); Specification for the use of Video and Audio Coding in DVB serv
33、ices delivered directly over IP protocols“. 2.2 Informative 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 latest version
34、of the referenced document (including any amendments) applies. NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee their long term validity. The following referenced documents are not necessary for the application of the present document bu
35、t they assist the user with regard to a particular subject area. i.1 ETSI TS 102 542-1: “Digital Video Broadcasting (DVB); Guidelines for the implementation of DVB-IPTV Phase 1 specifications; Part 1: Core IPTV Functions“. i.2 ETSI TS 102 542-3-1: “Digital Video Broadcasting (DVB); Guidelines for th
36、e implementation of DVB-IPTV Phase 1 specifications; Part 3: Error Recovery; Sub-part 1: Overview of DVB-IPTV Error Recovery“. i.3 ETSI TS 102 542-3-3: “Digital Video Broadcasting (DVB); Guidelines for the implementation of DVB-IPTV Phase 1 specifications; Part 3: Error Recovery; Sub-part 3: Retrans
37、mission (RET); IPTV Implementation Guidelines“. ETSI ETSI TS 102 542-3-2 V2.1.1 (2016-04) 7 3 Abbreviations For the purposes of the present document, the following abbreviations apply: AL-FEC Application Layer - Forward Error Correction AVC Advanced Video Coding CBMS Convergence of Broadcast and Mob
38、ile Services DF Digital Fountain DMA Direct Memory Access DSL Digital Subscriber LineDVB Digital Video Broadcasting DVB-TM Digital Video Broadcasting - Technical Module FEC Forward Error Correction HD High Definition IP Internet ProtocolIPI IP Infrastructure IPTV IP TeleVision KB Kilo ByteMIPS Mega
39、Instructions Per Second MPEG Moving Picture Experts Group PLR Packet Loss Ratio REIN Repetitive Electrical Impulse Noise RTCP Real-time Transport Control Protocol RTP Real-time Transport Protocol SD Standard Definition SD the AL-FEC overhead. The AL-FEC block size is the number of packets which are
40、protected together as a block, or equivalently the time required to send those packets at the stream rate (“protection period“). The AL-FEC overhead is the amount of additional FEC data (“repair packets“) that are sent as a fraction of the original data. For example, if the AL-FEC block size is 100
41、packets and 10 repair packets are sent for each block, then the AL-FEC overhead is 10 %. In order to determine the AL-FEC protection required, a good understanding of the loss characteristics of the target network is required. In general, the objective of AL-FEC is to provide error-free reception ov
42、er long periods of time (several hours) - loss events which cannot be corrected by the AL-FEC should therefore be very rare. This means that loss characteristics have to be understood over long time periods. The AL-FEC code operates on each FEC block independently. This means that loss characteristi
43、cs also have to be understood at a timescale equal to the FEC block size: averages over long time periods are not sufficient. For example, the average packet loss over a one hour period may be very low, but if many of the losses are concentrated in a short period of time they may still overwhelm the
44、 AL-FEC code. Clauses 5.1 and 5.2 provide some general guidelines on the effect of configuration parameters targeted at correcting for burst and random loss respectively. In practice, losses are a combination of these two. 5.1 Correcting for burst losses In order to correct for isolated burst losses
45、, a number of repair packets greater than or equal to the worst expected burst loss has to be provided for each FEC block. If only the AL-FEC base layer is used, then a number of repair packets equal to the worst expected burst loss has to be provided. Note that for the base layer, the number of rep
46、air packets per block has to be a divisor of the block size (in packets). This configuration will correct for isolated burst losses, but will often not correct randomly distributed losses and generally cannot correct for cases where multiple bursts occur within a block. When the AL-FEC base and enha
47、ncement layers are used, it is generally sufficient to provide a number of repair packets one greater than the worst expected burst loss per block. This configuration generally can also correct for randomly distributed losses or multiple bursts per block provided sufficient enhancement layer packets
48、 are sent. Note that the number of repair packets required per block is fixed independent of the block size. As a result longer block sizes will result in a lower relative AL-FEC overhead. However, longer block sizes will also contribute additional latency, affecting channel change times. 5.2 Correc
49、ting for random losses In order to correct for randomly distributed losses, it is necessary to understand the “worst case“ number of lost packets within an FEC block. If losses were truly random and independent, then the statistical probability of losing 1, 2, 3, etc. packets in a block could be calculated and from these probabilities the expected frequency of such events could also be calculated. The “worst case“ of interest is then the worst case occurring frequently enough to be an issue from a quality perspective (which is a judgement issue
