1、 International Telecommunication Union ITU-T H.262TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Corrigendum 2(05/2006) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMSInfrastructure of audiovisual services Coding of moving video Information technology Generic coding of moving pictures and associated a
2、udio information: Video Technical Corrigendum 2 ITU-T Recommendation H.262 (2000) Technical Corrigendum 2 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 mu
3、ltiplexing and synchronization H.220H.229 Systems aspects H.230H.239 Communication procedures H.240H.259 Coding 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 multime
4、dia services H.350H.359 Quality of service architecture for audiovisual and multimedia 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-Se
5、ries multimedia systems and services H.510H.519 Mobile multimedia collaboration applications 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.550
6、H.559Mobile multimedia collaboration inter-working procedures H.560H.569 BROADBAND AND TRIPLE-PLAY MULTIMEDIA SERVICES Broadband multimedia services over VDSL H.610H.619 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. H.262 (2000)/Cor.2 (05/2006) i INTERNATIONAL ST
7、ANDARD ISO/IEC 13818-2 ITU-T RECOMMENDATION H.262 Information technology Generic coding of moving pictures and associated audio information: Video Technical Corrigendum 2 Source Corrigendum 2 to ITU-T Recommendation H.262 (2000) was approved on 29 May 2006 by ITU-T Study Group 16 (2005-2008) under t
8、he ITU-T Recommendation A.8 procedure. An identical text is also published as Technical Corrigendum 2 to ISO/IEC 13818-2. ii ITU-T Rec. H.262 (2000)/Cor.2 (05/2006) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. T
9、he ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Stand
10、ardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce 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
11、 technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Co
12、mpliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other o
13、bligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implement
14、ation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As
15、 of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to
16、consult the TSB patent database. ITU 2006 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. H.262 (2000)/Cor.2 (05/2006) iii CONTENTS Page 1) Clause 2 “Normative references“ . 1 2) Subclause 5.4 “Arith
17、metic precision“ 1 3) Clause 7 “The video decoding process“. 1 4) Subclause 7.4.4 “Mismatch control“. 1 5) Subclause 7.5 “Inverse DCT“ 2 6) Subclause 7.6 “Motion compensation“ 2 7) Annex A “Inverse discrete transform“ 3 ISO/IEC 13818-2:2000/Cor.2:2006 (E) ITU-T Rec. H.262 (2000)/Cor.2 (05/2006) 1 IN
18、TERNATIONAL STANDARD ITU-T RECOMMENDATION Information technology Generic coding of moving pictures and associated audio information: Video Technical Corrigendum 2 1) Clause 2 “Normative references“ In clause 2, make the following changes. Insert the following reference. ISO/IEC 23002-1:2006, Informa
19、tion technology MPEG video technologies Part 1: Accuracy requirements for implementation of integer-output 8x8 inverse discrete cosine transform. Remove the following reference: IEEE 1180:1990, Standard Specifications for the Implementations of 8 by 8 Inverse Discrete Cosine Transform. 2) Subclause
20、5.4 “Arithmetic precision“ In subclause 5.4, replace the paragraph which states as follows: a) Where arithmetic precision is not specified, such as in the calculation of the IDCT, the precision shall be sufficient so that significant errors do not occur in the final integer values. with the followin
21、g: a) Where an arithmetically-precise result is not fully specified, such as in the calculation of the IDCT, the precision shall be sufficient so that significant errors do not occur in the final integer values. 3) Clause 7 “The video decoding process“ In clause 7, replace the paragraph which states
22、 as follows: The IDCT function fyx used in the decoding process may be any of several approximations of the saturated mathematical integer-number IDCT defined in Annex A. Requirements on the accuracy of the IDCT function used in the decoding process are specified in Annex A. with the following: The
23、IDCT function used in the decoding process for computation of fyx may use any method of integer approximation of the mathematical integer-number IDCT defined in Annex A, provided the approximation conforms to the accuracy requirements specified in Annex A. 4) Subclause 7.4.4 “Mismatch control“ In su
24、bclause 7.4.4, replace Note 2 which states as follows: NOTE 2 Warning Small non-zero inputs to the IDCT may result in zero output for compliant IDCTs. If this occurs in an encoder, mismatch may occur in some pictures in a decoder that uses a different compliant IDCT. An encoder should avoid this pro
25、blem and may do so by checking the output of its own IDCT. It should ensure that it never inserts any non-zero coefficients into the bitstream when the block in question reconstructs to zero through its own IDCT function. If this action is not taken by the encoder, situations can arise where large a
26、nd very visible mismatches between the state of the encoder and decoder occur. ISO/IEC 13818-2:2000/Cor.2:2006 (E) 2 ITU-T Rec. H.262 (2000)/Cor.2 (05/2006) with the following: NOTE 2 Warning Small non-zero inputs to the IDCT may result in all-zero output for some IDCT approximations that conform to
27、 the requirements specified in Annex A. If this occurs in an encoder, a mismatch may occur in decoders that use a different conforming IDCT approximation than the approximation used in modelling the decoding process within the encoder. An encoder should avoid this problem and may do so by checking t
28、he output of its own IDCT approximation. It should ensure that it never inserts any non-zero coefficients into the bitstream when the block in question reconstructs to zero through the encoders own IDCT function approximation. If this action is not taken by the encoder, situations can arise where la
29、rge and very visible mismatches between the state of the encoder and decoder occur. 5) Subclause 7.5 “Inverse DCT“ Replace subclause 7.5, which states as follows: 7.5 Inverse DCT Once the DCT coefficients, Fvu are reconstructed, an IDCT transform that conforms to the specifications of Annex A shall
30、be applied to obtain the inverse transformed values fyx. with the following: 7.5 Inverse DCT Once the DCT coefficients, Fvu are reconstructed, an IDCT function that conforms to the accuracy requirements specified in Annex A shall be applied to obtain the integer inverse transformed values fyx. 6) Su
31、bclause 7.6 “Motion compensation“ In subclause 7.6, third paragraph, make the following changes: Replace the sentence stating “The saturation shown in Figure 7-5 is still required in order to remove negative values from fyx“ with “The saturation shown in Figure 7-5 is still required in order to remo
32、ve negative values and values in excess of 255 (if present) from fyx“. Insert the following additional paragraphs: For establishing a requirement of bitstream conformance, for each macroblock in a P-picture, a prediction count increment value shall be derived as follows. If a macroblock in the curre
33、nt picture is skipped, its prediction count increment value shall be equal to 0. Otherwise, its prediction count increment value shall be equal to 1. For establishing a requirement of bitstream conformance, for each macroblock in each I-picture and P-picture, a prediction count shall be derived as f
34、ollows. If a macroblock is an intra coded macroblock, its prediction count shall be equal to 0. Otherwise, if the current picture is a field picture and the most recently reconstructed reference picture is also a field picture or if the current picture is a frame picture and the most recently recons
35、tructed reference picture is also a frame picture, the prediction count for a macroblock in the current picture shall be equal to the prediction count increment value plus the value of the prediction count for the macroblock in the most recently reconstructed reference picture that corresponds to th
36、e position of the selected macroblock in the current picture. Otherwise, the prediction count for a macroblock in the current picture shall be equal to the prediction count increment value plus the maximum of the values of the two prediction counts for the two macroblocks in the area of the most rec
37、ently reconstructed reference picture that corresponds to the position of the selected macroblock in the current picture. It is a requirement of bitstream conformance that for each macroblock in a P-picture, the value of the resulting prediction count shall be less than 132. ISO/IEC 13818-2:2000/Cor
38、.2:2006 (E) ITU-T Rec. H.262 (2000)/Cor.2 (05/2006) 3 7) Annex A “Inverse discrete transform“ Replace Annex A, which states as follows: Annex A Inverse discrete transform (This annex forms an integral part of this Recommendation | International Standard) The N N two dimensional DCT is defined as: N2
39、v)1y2(cosN2u)1x2(cosy)f(x,C(u)C(v)N2v)F(u,1N0x1N0y+=with u, v, x, y = 0, 1, 2, . N 1 where x, y are spatial coordinates in the sample domain u, v are coordinates in the transform domain C(u), C(v) = =otherwise10vufor21The definition of the DCT (also called forward DCT) is purely informative. Forward
40、 DCT is not used by the decoding process described by this Specification. The mathematical real-number IDCT is defined as: N21)v(2ycosN21)u(2xcos v)u,C(u)C(v)F(N2y)f(x,1N0u1N0+=vf (x, y) is a real number. The mathematical integer-number IDCT is defined as: f (x, y) = round(f(x, y) where round() is t
41、he rounding to the nearest integer, with half-integer values rounded away from zero. No clamping or saturation is performed. The saturated mathematical integer-number IDCT is defined as: f “(x, y) = saturate(f (x, y) where saturate() is the saturation in the range 256, 255, defined as: saturate (x)
42、= 256, fyx shall be equal to 255 and when f (x, y) 257, fyx shall be equal to 256. For all values of f (x, y) in the range 257, 256 the absolute difference between fyx and f “(x, y) shall not be larger than 2. 4) Let F be the set of 4096 blocks Biyx (i = 0 4095) defined as follows: a) Bi00 = i 2048.
43、 b) Bi77 = 1 if Bi00 is even, Bi77 = 0 if Bi00 is odd. c) All other coefficients Biyx other than Bi00 and Bi77 are equal to 0. For each block Biyx that belongs to set F defined above, an IDCT that conforms to this specification (see Annex A) shall output a block fyx that has a peak error of 1 or les
44、s compared to the reference saturated mathematical integer-number IDCT f “(x, y). In other words, | fyx f “(x, y) | shall be = 1 for all x and y. In addition to these requirements, the following is a recommendation on the accuracy of the IDCT function fyx. 5) When item 3) does not apply, i.e., for i
45、nput blocks of DCT coefficients causing the output of the mathematical integer-number IDCT f (x, y) to contain one or more values out of the range 384, 383, it is desirable that fyx be as close as possible to f “(x, y) for all bitstreams produced by reasonably well-designed encoders. NOTE Clause 2.3
46、 IEEE Standard 1180-1990 “Considerations of Specifying IDCT Mismatch Errors“ requires the specification of periodic intra-picture coding in order to control the accumulation of mismatch errors. Every macroblock is required to be refreshed before it is coded 132 times as predictive macroblocks. Macro
47、blocks in B-pictures (and skipped macroblocks in P-pictures) are excluded from the counting because they do not lead to the accumulation of mismatch errors. This requirement is the same as indicated in 1180-1990 for visual telephony according to Recommendation H.261. with the following. Annex A Inve
48、rse discrete cosine transform (This annex forms an integral part of this Recommendation | International Standard) The N N two-dimensional mathematical real-number IDCT is defined as: N2v)1y2(cosN2u)1x2(cosv)u,C(u)C(v)F(N2y)f(x,1N0u1N0v+=with u, v, x, y = 0, 1, 2, N 1 where x, y are spatial coordinat
49、es in the sample domain u, v are coordinates in the transform domain f(x, y) and F(u, v) are real numbers for each pair of values (x, y) and (u, v) is Archimedes constant 3,141 592 653 589 793 238 462 643 . C(u), C(v) = =otherwise10vufor21ISO/IEC 13818-2:2000/Cor.2:2006 (E) ITU-T Rec. H.262 (2000)/Cor.2 (05/2006) 5 The N N two-dimensional mathematica
