1、 STD.ETS1 TR LOO 815-ENGL 1999 = 3400855 038LOb3 422 TR 1 O0 81 5 1.1.1 (1999-02) Technical Report Digital Video Broadcasting (DVB); Guidelines for the handling of Asynchronous Transfer Mode (ATM) signals in DVB systems STDOETSI TR LOO 815-ENGL 1999 m 3400855 0381064 869 m 2 TR 100 815 Vl.l.1 (1999-
2、02) Reference DTWJTC-DVB-30 (7joOOics.PDF) Kevwords ATM, broadcasting, digital, DVB, N, video ETSI Postal address F-O6921 Sophia Antipolis Cedex - FRANCE Office address 650 Route des Lucioles - Sophia Antipolis Valbonne - FRANCE Siret No 348 623 562 00017 - NAF 742 C Association but non lucratif enr
3、egistre la Sous-Prfecture de Grasse (06) No 7803/88 Tel.: +33 4 92 94 42 O0 Fax: +33 4 93 65 47 16 Internet secretariatetsi.fr Individual copies of this ETSI deliverable can be downloaded from http:i/www.etsi.org If you find errors in the present document, send your comment to: editoretsi.fr Copyrig
4、ht Notification No part may be reproduced except as authorized by Writen permission. The copyright and the foregoing restriction extend to reprcduction in all media. Q European Telecommunications Standards Institute 1999. Q European Broadcasting Union 1999. AU rights reserved. ETSI STDmETSI TR LOO 8
5、15-ENGL 1999 M 3400655 03B10h5 7T5 TR 1 O0 81 5 V1 . 1.1 (1 99942) 3 Contents Intellectual Property Rights 4 Foreword 4 1 2 3 3.1 3.2 4 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 Scope 5 References 5 Abbreviations and definitions 6 Abbreviations . 6 Definitions . 6 System description . 6 Mapping of ATM cells int
6、o DVBMEG-2 Transport Stream . 7 Frame format 7 Ceii rate adaptation 8 Header Error Control (HEC) generation 8 Scrambling of the ATM cell payload . 8 Ceii delineation 8 Cell header venfication and extraction 8 Physical iayer Operation And Maintenance (OAM) 9 signai processing for PLOAM cells in the t
7、ransmitter 9 signai processing for PLOAM cells in the receiver 10 5.7.1 5.7.2 6 Implementation aspects 10 ATM to WEG-TS gateway and MPEG-TS multiplexer 10 6.1 6.2 MPEG-TS demultiplexer . 11 7 Conditional Access 11 History 12 ETSI STD-ETSI TR 100 815-ENGL 1999 I 3400855 038LObb b3L H 4 TR 100 815 V1.
8、l.l (1999-02) Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essentiai IPRs, if any, is publicly available for ETSI members and non-members, and can be found in SR O00 314 “Intellecfuul
9、Property Rights (IPRs); Essential, orpotentially Essential, IPRs notijed to ETSI in respect ofETSZ standards”, which is available free of charge from the ETSI Secretariat. Latest updates are available on the ETSI Web server (http:/www.etsi.org/ipr). huant to the ETSI IPR Policy, no investigation, in
10、cluding IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in SR O00 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 Report (TR) has been pr
11、oduced by the Joint Technical Committee (JTC) Broadcast of the European Broadcasting Union BU), Comit Europen de Normalisation ELECtrotechnique (CENELEC) and the European Telecommunications Sandards Institute (ETSI). NOTE: The EBU/ETSI JTC Broadcast was established in 1990 to Co-ordinate the draftiu
12、g of sandards 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 EBU is a professional associ
13、ation of broadcasting organizations whose work includes the Co-ordination of its members activities in the technical, legal, programme-making and progrunme-exchange domains. The EBU has active members in about 60 countries in the Eusopean broadcasting area; its headquarters is in Geneva. European Br
14、oadcasting Union CH-1218 GRAND SACONNEX (Geneva) Switzerland Tel: Fax: +41 22 717 21 11 +41 22 717 24 81 Digital Video Broadcasting (DVB) Project Founded in September 1993, the DVB Project is amarket-led consortium of public and private sector organizations in the television industry. Its aim is to
15、establish the framework for the introduction of MPEG-2 based digital television services. Now comprising over 200 organizations frommore than 25 countries around the world, DVB fosters market-led systems, which meet the real needs, and economic circumstances, of the consumer electronics and the broa
16、dcast industry. ETSI 5 TR 1 O0 81 5 V1.l.l (1 99942) 1 Scope The present document provides the mapping scheme to be used for the transport of ATM cells over WEG-2 Transport Stream packets. The purpose of encapsulating ATM cells directly into an WEG-2 transport stream is to: The main constraints of t
17、his problem are to: interconnect ATM networks via DVB systems or provide ATM services to end-users using DVB systems; offer differentiated qdity of service to end-users by utilizing the ATM mechanisms. providing an efficient encapsulation mechanism; maintaining DVBMPE?G-2 compatibility when transpor
18、ting ATM cells; respecting ATM Quality-of-Service requirements thoughout DVB/MPEG systems. 2 References The following documents contain provisions which, through reference in this text, constitute provisions of the present document. References are either specific (identified by date of publication,
19、edition number, version number, etc.) or non-specific. For a specific reference, subsequent revisions do not apply. For a non-specific reference, the latest version applies. A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the same number. il
20、AF-PHY-0017.000: “The ATM Forum Technical Committee, UTOPIA Specification, Level 1, Version 2.01“. 21 31 EN 301 192: “Digital Video Broadcasting (DVB); DVB specification for data broadcasting“. IT-T Recommendation G.826: “Error performance parameters and objectives for international, constant bit ra
21、te digital paths at or above the primary sate“. ITU-T Recommendation 1.356: “B-ISDN ATM iayer cell transfer performance“. ITU-T Recommendation 1.371: “Traffic control and congestion control in B-ISDN“. ITU-T Recommendation 1.432.1: “B-ISDN user-network interface - Physical layer specifications: Gene
22、ral characteristics“. ITU-T Recommendation 1.432.2: “B-ISDN user-network interface - Physical layer specification: 155 520 kbit/s and 622 O80 kbitk operation“. ITU-T Recommendation 1,610: “B-ISDN operation and maintenance principles and functions“. ISO/IEC 13818-1: “Information technology - Generic
23、coding of moving pictures and associated audio information: Systems“. 41 PI i61 71 SI 191 STDeETSI TR 100 815-ENGL Lqqq 3400855 0383068 404 D 100 815 V1.1.1 (1999-02) 6 3 Abbreviations and definitions 3.1 Abbreviations For the purpose of the present document, the following abbreviations apply: ATM C
24、DV CEC CRC EDC HEC LOC LOS MPEG-TS OM PCR PES PID PL QOS RDI REF3 SAR TS VBR vc VP Asynchronous Transfer Mode Cell Delay Variation Cell Error Control Cyclic Redundancy Check Error Detection Code Header Emor Control Loss Of Cell delineation Loss Of Signal WEG Transport Stream Operation, Administratio
25、n and Maintenance Program Clock Reference Packetized Elementary Stream Packet Identifier Physical Layer Quaiity of Service Remote Defect Indication Remote Errored Blocks Segmentation And Re-assembly Transport Stream Variable Bit Rate Virtualchannel Virtual Path 3.2 Definitions For the purposes of th
26、e present document, the following terms and definitions apply: idle cell: a cell which is inserted and extracted by the physical layer in order to adapt the cell flow rate at the boundary between the ATM layer and the physical layer to the available payload capacity of the transmission used. valid c
27、ell: a cell whose header has no errors or has been modified by the cell Header Error Control (HEC) verification process. 4 System description The standard DVBIMPEG system defines all functionalitys for encoding video and audio into MPEG Transport Streams (TSs), which are then multiplexed, along with
28、 data, into a single Transport Stream This multiplex is modulated for transmission over the network. At the receiver side, the demodulator ouiputs the multiplex to a Transport Stream demultiplexer which extracts individual streams. The goal of this guideline is to give recommendations on carrying na
29、tive ATM services using the standard DVBMPEG system. Figure 1 shows an end-to-end DVBMPEG conceptual block diagram, where additional blocks have been added to insert ATM cells into the system and extract ATM cells at the user side. ETSI STD.ETS1 TR 100 L5-ENGL 1999 3400855 038l1067 340 7 TR 100 815
30、V1.1.1 (1999-02) The 188 bytes (4 bytes header) MPEG transport packet is part of the data link sublayer defined to cany MPEG-2 video, audio, and data streams in DVB system. A segmentation and re-assembly mechanism is needed to segment each information stream into WEG-TS packets. Different schemes ar
31、e presently defined in the MPEG standard ISOIIEC 13818-1 9 and the DVB data broadcasting standard EN301 1922. In the MPEG standard ISOIIEC 13818-1 9, the Packetized Elementary Stream (FES) and the Private Section are defined. For PES, WEG defines an Adaptation Field mechanism which provides a techni
32、que to stuff MPEG-TS packets with stuffhg bytes when transmit buffers are empty. For Private Sections, MPEG only defines a minimum structure. DVB specifies a formt for the Private Sections in order to carry Multi-Protocol Encapsulation which can transport any type of Network Layer traffic. Also, ano
33、ther scheme defined by DVB is called data piping, consists in putting the raw traffk directly over MPEG-TS packets without any extra overhead. In ATM, the typical data link layer is composed of 53 bytes cells (5 bytes header) and is using its own segmentation and re-assembly mechanism (AAL). Usually
34、, ATM cells are transported directly over a physical medium, which has its own transmission mechanism Although ATM cells are asynchronous by nature, they are usually transmitted over the physical medium of a synchronous hierarchy network. Transmit and Receive buffers take care of following the const
35、raints defined by IT-T Recommendation 1.356 4. - 0000 Video MPEG2 encoder DODO Modulator MPEG-TS MUX l I Video server I Encapsulation ATM witch or multiplexing m DVB transmission jT+Aj ATM from MPEGTS De-Encapsulation Figure 1: Conceptual DVBIMPEG chain carrying ATM 5 Mapping of ATM cells into DVB/M
36、PEG-2 Transport Stream 5.7 Frame format The basic MPEG-TS packet structure of 188 octets as described inISOIIEC 13818-1 9 shall be used. The ATM cells are mapped into the 184 payload octets of the TS packet with the octet structure of the cell aligned with the octet structure of the packet. The data
37、 piping mechanism described in EN 301 192 2 shall be used to transport ATM cells in MPEG-TS packets. The 53 bytes ATM valid cells are consecutively inserted into the 184 bytes payload of the MPEG- TS packets. When valid cells are not available from the ATM layer, the mechanism described in subclause
38、 5.2 shall be used. ETSI STD-ETSI TR LOO 815-ENGL 1999 9 3400855 0381070 Ob2 W ATM ATM 8 TR 1 O0 81 5 V1.l.l (1 99942) ATM ATM SQIt 5.2 Cell rate adaptation Adapt ATM ATM ATM FIdd The cell rate adaptation to the payload capacity of the MPEG-TS packets is performed either (i) by the insertion of idle
39、 cells, as described in ITU-T Recommendation 1.4321 6 (see Figure 2), or (ii) by using the MPEG-TS adaptation fields mechanism, as described in ISO/IEC 13818-1 9 (see Figure 3). A combination of these two mechanisms is possible. The start of an idle cell at the end of an MPEG-TS packet shall be comp
40、leted at the beginning of the next packet with the same PID. The MPEG adaptation fields mechanism ailows that the next WEG-TS packet can start immediately with a new valid cell. if available. ATM ATM ATM packet n packet n+l Figure 2: Idle cells inserted into the stream packet n packet n+ 1 Figure 3:
41、 Adaptation fields inserted into the MPEG-TS header When no valid cell is available from the ATM layer during the transmission of a full MPEG-TS packet, either (i) the MPEG-TS packet is transmitted filled up with idle cells, or (ii) a NULL MPEG-TS packet is sent to the transport multiplexer. 5.3 Hea
42、der Error Control (HEC) generation The HEC value is generated and inserted in the specific field in compliance with ITU-T Recommendation 1.432.1 6. 5.4 Scrambling of the ATM cell payload The ATM cell payload (48 bytes) shall be scrambled before mapping into the MPEG-TS. In the reverse operation, fol
43、lowing termhation of the WEG-TS, the ATM cell payload will be descrambled before being passed to the ATM layer. A self-synchronizing scrambler with the generator polynomial x“ + 1, as described in ITU-T Recommendation 1.432.1 6, shall be used. Cell payload field scrambling is required to provide sec
44、urity against false cell delineation and replication of the WEG-TS packets synchronization. 5.5 Cell delineation The cell delineation shall be performed using the Header Enor Control (HEC) mechanism as defined in ITU-T Recornmendation.432.16. The mechanism for the detection of loss and recovery of c
45、ell delineation shall follow the description given in subclause 8.2.2 of ITU-T Recommendation 1.432.2 7. Loss Of Cell delineation &OC) causes a LCD defect. 5.6 Cell header verification and extraction The cell header verification shall be performed in compliance with ITU-T Recommendation 1.432.1 163.
46、 All the physical layer cells shall be extracted and only the valid cells are passed to the ATM layer. Idle cells are discarded. 5.7 9 TR 1 815 V1.3.1 (199902) Physical layer Operation And Maintenance (OAM) OAM flows defined in IT-T Recommendation 1.610 8 for ATM shall be transmitted dong with traff
47、ic flows according to the present document. F1-F3 are physicai layer related OAM flows, whereas F4P5 flows are ATM iayer related and are camied using ATM celis with a specific VCI. In order to avoid specific definitions in the WEG-TS for ATM maintenance, F1 and F3 flows shaii be carried in maintenan
48、ce cells (PLOAM) using a specific pattern in the header as defined for ceil based transmission systems. The ATM cell header and the allocation of OAM functions in the information field of these special ATM celis shall follow the description given in subclause 7.2.2 of ITU-T Recommendation 1.432.2 7.
49、 These cels are not passed to the ATM layer. F2 flow is not provided, but the associated functions are supported by p3 flows. Each MPEG stream shall carry its OW Pl-F3 flows. Maximum spacing between PL-OAM cells: The spacing between two adjacent PGOAM cells is 216 celis using the block boundaries as described in subclause 7.2.2.3 of ITU-T Recommendation 1.432.2 7. This interval consists of 8 monitored blocks with each block containing 27 cells. 5.7.1 Signal processing for PL-OAM cells in the transmitter a) Continuity
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