1、 International Telecommunication Union ITU-T H.241TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (02/2012) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMSInfrastructure of audiovisual services Communication procedures Extended video procedures and control signals for ITU-T H.300-series terminals Recom
2、mendation ITU-T H.241 ITU-T H-SERIES RECOMMENDATIONS AUDIOVISUAL AND MULTIMEDIA SYSTEMS CHARACTERISTICS OF VISUAL TELEPHONE SYSTEMS H.100H.199 INFRASTRUCTURE OF AUDIOVISUAL SERVICES General H.200H.219 Transmission multiplexing and synchronization H.220H.229 Systems aspects H.230H.239 Communication p
3、rocedures H.240H.259Coding of moving video H.260H.279 Related systems aspects H.280H.299 Systems and terminal equipment for audiovisual services H.300H.349 Directory services architecture for audiovisual and multimedia services H.350H.359 Quality of service architecture for audiovisual and multimedi
4、a services H.360H.369 Supplementary services for multimedia H.450H.499 MOBILITY AND COLLABORATION PROCEDURES Overview of Mobility and Collaboration, definitions, protocols and procedures H.500H.509 Mobility for H-Series multimedia systems and services H.510H.519 Mobile multimedia collaboration appli
5、cations and services H.520H.529 Security for mobile multimedia systems and services H.530H.539 Security for mobile multimedia collaboration applications and services H.540H.549 Mobility interworking procedures H.550H.559 Mobile multimedia collaboration inter-working procedures H.560H.569 BROADBAND,
6、TRIPLE-PLAY AND ADVANCED MULTIMEDIA SERVICES Broadband multimedia services over VDSL H.610H.619 Advanced multimedia services and applications H.620H.629 Ubiquitous sensor network applications and Internet of Things H.640H.649 IPTV MULTIMEDIA SERVICES AND APPLICATIONS FOR IPTV General aspects H.700H.
7、719 IPTV terminal devices H.720H.729 IPTV middleware H.730H.739 IPTV application event handling H.740H.749 IPTV metadata H.750H.759 IPTV multimedia application frameworks H.760H.769 IPTV service discovery up to consumption H.770H.779 For further details, please refer to the list of ITU-T Recommendat
8、ions. Rec. ITU-T H.241 (02/2012) i Recommendation ITU-T H.241 Extended video procedures and control signals for ITU-T H.300-series terminals Summary Recommendation ITU-T H.241 defines the use of advanced video codecs, including those based on Recommendation ITU-T H.264, in ITU-T H.300-series termina
9、ls, including ITU-T H.310, ITU-T H.320, ITU-T H.321, ITU-T H.322, ITU-T H.323 and ITU-T H.324 terminals. It also defines generic extended signalling for use with all video codecs in the ITU-T H.300-series terminals. This revised version introduces a number of enhancements and clarifications to the p
10、revious version. Clarification concerns primarily the description on the signalling for ITU-T H.264 Annex G Scalable Baseline and Scalable High Profiles, a procedure for selecting the operating point of a scalable video coding (SVC) video stream, and the Capability Class of ITU-T H.241 capabilities.
11、 This version incorporates clause 6.2.5 introduced in ITU-T H.241 (2006) Amd. 1 (2008), allowing for the negotiation of particular video submodes of ITU-T H.264 encoding. It also incorporates clause 8.3.2.14, defining a new optional ITU-T H.264 capability parameter (MaxFPS), and Appendix II which co
12、ntains non-normative examples describing the use of clause 6.2.5. Clause 8.3.2.14 and Appendix II were both introduced in ITU-T H.241 (2006) Amd. 2 (2009). History Edition Recommendation Approval Study Group 1.0 ITU-T H.241 2003-07-14 16 1.1 ITU-T H.241 (2003) Cor. 1 2004-03-15 16 1.2 ITU-T H.241 (2
13、003) Amd. 1 2005-01-08 16 2.0 ITU-T H.241 2005-09-13 16 3.0 ITU-T H.241 2006-05-29 16 3.1 ITU-T H.241 (2006) Amd. 1 2008-06-13 16 3.2 ITU-T H.241 (2006) Amd. 2 2009-12-14 16 3.3 ITU-T H.241 (2006) Cor. 1 2011-05-14 16 4.0 ITU-T H.241 2012-02-29 16 ii Rec. ITU-T H.241 (02/2012) FOREWORD The Internati
14、onal Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operat
15、ing and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, pro
16、duce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In th
17、is Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., i
18、nteroperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not sugges
19、t that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the eviden
20、ce, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be
21、required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2012 All rights reserved. No part of this publication may be repr
22、oduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T H.241 (02/2012) iii Table of Contents Page 1 Scope 1 2 References. 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 2 4 Abbreviations and acronyms 2 5 Conventions 3 5.1
23、System terminology 3 5.2 Message names . 3 5.3 Requirement terminology . 4 6 Commands and indications . 4 6.1 Control and ndication (C users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references
24、listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T H.221 Recommendation ITU-T H.221 (2009), Frame structure for a 64 to 1 9
25、20 kbit/s channel in audiovisual teleservices. ITU-T H.230 Recommendation ITU-T H.230 (2009), Frame-synchronous control and indication signals for audiovisual systems. ITU-T H.239 Recommendation ITU-T H.239 (2005), Role management and additional media channels for H.300-series terminals. ITU-T H.242
26、 Recommendation ITU-T H.242 (2009), System for establishing communication between audiovisual terminals using digital channels up to 2 Mbit/s. ITU-T H.243 Recommendation ITU-T H.243 (2005), Procedures for establishing communication between three or more audiovisual terminals using digital channels u
27、p to 1 920 kbit/s. ITU-T H.245 Recommendation ITU-T H.245 (2011), Control protocol for multimedia communication. ITU-T H.261 Recommendation ITU-T H.261 (1993), Video codec for audiovisual services at p 64 kbit/s. ITU-T H.262 Recommendation ITU-T H.262 (2000), Information technology Generic coding of
28、 moving pictures and associated audio information: Video. ITU-T H.263 Recommendation ITU-T H.263 (2005), Video coding for low bit rate communication. 2 Rec. ITU-T H.241 (02/2012) ITU-T H.264 Recommendation ITU-T H.264 (2011), Advanced video coding for generic audiovisual services. ITU-T H.310 Recomm
29、endation ITU-T H.310 (1998), Broadband audiovisual communication systems and terminals. ITU-T H.320 Recommendation ITU-T H.320 (2004), Narrow-band visual telephone systems and terminal equipment. ITU-T H.323 Recommendation ITU-T H.323 (2009), Packet-based multimedia communications systems. ITU-T H.3
30、24 Recommendation ITU-T H.324 (2009), Terminal for low bit-rate multimedia communication. IETF RFC 3550 IETF RFC 3550 (2003), RTP: A Transport Protocol for Real-Time Applications. IETF RFC 6184 IETF RFC 6184 (2011), RTP Payload Format for H.264 Video. IETF RFC 6190 IETF RFC 6190 (2011), RTP Payload
31、Format for Scalable Video Coding. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: None. 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 picture aspect ratio: The ratio between the intended horiz
32、ontal width and the intended vertical height of a displayed picture. Picture aspect ratio is expressed as h:v, where h is horizontal width and v is vertical height (in arbitrary units of spatial distance). For the purposes of this definition, a picture is the complete displayed image (including both
33、 fields in the case of interlaced-scan video). For example, the picture aspect ratio for a common intermediate format (CIF) picture according to ITU-T H.263 is 4:3. 3.2.2 sample aspect ratio: The ratio between the intended horizontal distance between the columns and the intended vertical distance be
34、tween the rows of the luma sample array in a frame. Sample aspect ratio is expressed as h:v, where h is horizontal width and v is vertical height (in arbitrary units of spatial distance). For the purposes of this definition, a sample is an individual luma picture element (pixel) making up the comple
35、te displayed image (including both fields in the case of interlaced-scan video). For example, the sample aspect ratio for a CIF picture according to ITU-T H.263 is 12:11. 3.2.3 terminal: A terminal is any end point and may be a users terminal or some other communication system such as a multipoint c
36、ontrol unit (MCU) or an information server. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: 4CIF 4x Common Intermediate Format 4SIF 4x Standard Interchange Format AL-SDU Adaptation Layer Service Data Unit Rec. ITU-T H.241 (02/2012) 3 ASN.1 Abstract Syn
37、tax Notation One BAS Bit-rate Allocation Signal C these include ITU-T H.320, ITU-T H.321 and ITU-T H.322 systems “ITU-T H.245-based systems“ refers to those systems that use signalling according to ITU-T H.245; these include ITU-T H.310, ITU-T H.323 and ITU-T H.324 systems. 5.2 Message names In this
38、 Recommendation, signalling messages which are common to both ITU-T H.245 and BAS signalling systems are referred to by their names, as given in Annex A of ITU-T H.245, except in cases where their use in the unique BAS signalling environment is described. Message names are presented in bold font to
39、distinguish them from the other text of this Recommendation. Table 5-1 provides a reference for corresponding ITU-T H.245 and ITU-T H.242/ITU-T H.230 messages mentioned in this Recommendation. 4 Rec. ITU-T H.241 (02/2012) Table 5-1 Corresponding ITU-T H.245 and BAS video signals ITU-T H.245 name ITU
40、-T H.230 mnemonic h263Options.customPictureClockFrequency CPCF h263Options.customPictureFormat CSFMT h263Options.customPictureFormat CPAR h263VideoCapability.enhancementLayerInfo SCLPREF lostPartialPicture lostPartialPicture lostPicture lostPicture recoveryReferencePicture recoveryReferencePicture v
41、ideoBadMBs VBMBC videoFastUpdateGOB videoFastUpdateGOB videoFastUpdateMB videoFastUpdateMB videoFastUpdatePicture VCU videoFreezePicture VCF videoNotDecodedMBs videoNotDecodedMBs videoSendSyncEveryGOB GHOP videoSendSyncEveryGOBCancel cancel-GHOP 5.3 Requirement terminology In this Recommendation the
42、 following conventions are used: “shall“ indicates a mandatory requirement “should“ indicates a suggested but optional course of action “may“ indicates an optional course of action rather than a recommendation that something take place. 6 Commands and indications 6.1 Control and ndication (C&I) appl
43、icable to all video codecs For further study. 6.2 C&I for use with ITU-T H.264 The following C&I signals shall not be used with regard to any channel operating according to ITU-T H.264: BAS signals CPCF, CSFMT, CPAR, SCLPREF lostPartialPicture lostPicture recoveryReferencePicture videoBadMBs videoFa
44、stUpdateGOB videoFastUpdateMB videoNotDecodedMBs videoSendSyncEveryGOB Rec. ITU-T H.241 (02/2012) 5 videoSendSyncEveryGOBCancel. NOTE 1 The above signals are either specific to ITU-T H.263 or have parameters which do not correspond to ITU-T H.264 structures or value ranges. Replacement signals which
45、 could be used either with ITU-T H.264 or in a generic form for any video codec are for further study. All other C&I not mentioned in this clause shall be used as specified elsewhere. NOTE 2 For example, the use of videoIndicateReadyToActivate and corresponding BAS signal VIR is not affected by this
46、 Recommendation. 6.2.1 videoFreezePicture command in ITU-T H.264 When a video decoder according to ITU-T H.264 receives a videoFreezePicture command, it shall freeze its displayed picture until one of the following events occurs: a) a recovery point signalled in a recovery point service end interfac
47、e (SEI) message (D.2.7 of ITU-T H.264) is reached b) reception of an instantaneous decoding refresh (IDR) picture c) A timeout period of at least six seconds has elapsed since the videoFreezePicture command was received. 6.2.2 videoFastUpdatePicture command in ITU-T H.264 When a video encoder accord
48、ing to ITU-T H.264 receives a videoFastUpdatePicture command, the encoder shall enter the fast update mode by using one of the procedures specified in clause 6.2.2.1 or 6.2.2.2 below. The procedure in 6.2.2.1 is the preferred response in a lossless transmission environment. Both procedures satisfy t
49、he requirement to enter the fast update mode for ITU-T H.264 video encoding. NOTE 1 The procedures re-initialize an ITU-T H.264 decoder completely so that valid video frames will be decoded. Such re-initialization is effective regardless of whether or not the decoder was previously decoding any video stream from any end point. The procedure should be accomplished as quickly as possible, but the re-initialization video stream shall be completely tran
