ITU-T Recommendations

This Recommendation defines the use of advanced video codecs, including ITU-T Rec. H.264, in ITU-T Recs H.310, H.320, H.321, H.322, H.323 and H.324 terminals. It also defines generic extended signalling for use with all video codecs in the H.300-series terminals.This revised version adds clarifications regarding H.264 VCL HRD (Type I HRD) versus NAL HRD (Type II HRD) bit rate usage, sample aspect ratio capabilities for H.264, signalling for Reduced Complexity Decoding Operation (RCDO) for H.264 bitstreams, and a new Annex B, "RCDO for H.264 Baseline Profile bitstreams". Annex A has been replaced with an inclusion by reference of the recently approved RFC 3984 (without actual change in content). New Annex B specifies a reduced-complexity decoding process to be applied to H.264 Baseline profile bitstreams when such use has been negotiated using ITU-T Rec. H.241.Amendment 1 to this Recommendation provides a new clause 6.2.5 allowing for the negotiation of particular video submodes of H.264 encoding along with associated additions to Appendix I. It also includes a new Appendix II which contains non-normative examples describing the use of this new clause.Amendment 2 to this Recommendation provides a new clause 8.3.2.14 defining a new optional H.264 capability parameter (MaxFPS). It also includes revised text for Appendix II.Corrigendum 1 to this Recommendation revises the units used for the CustomMaxDPB parameter value to 256/3 macroblocks, which makes this parameter consistent with Table A.1/H.264 (2010). The scaling of this revised parameter is carefully chosen to maintain interoperability with existing systems. The equation for the number of decoded frames in clause 8.3.2.6 is removed, as it produces incorrect results when applied to some H.264 picture formats. It is replaced with new text that applies to all picture formats and profiles. Corrigendum 1 also includes a note added to Table 8-8/H.241, clarifying that cpbBrVclFactor and cpbBrNALFactor units are not used for the value of the CustomMaxBRandCPB parameter.