Amendment 2 to ITU-T Rec. H.264 (a twin text Recommendation with ISO/IEC 14496-10) “Advanced video coding for generic audiovisual services” creates a set of new video coding profiles intended primarily for professional applications. It also defines two new types of supplemental enhancement information (SEI) messages.
One such new profile is the High 4:4:4 Predictive profile. The High 4:4:4 Predictive profile, as drafted herein, has two different 4:4:4 operation modes depending upon the value of a new syntax element, separate_colour_plane_flag that is present in the sequence parameter set. When separate_colour_plane_flag is equal to 0, each macroblock contains both luma and chroma samples, and a decoding process similar to the luma decoding process that is used in the other profiles is used to decode the luma and chroma samples in each such macroblock. When separate_colour_plane_flag is equal to 1, the decoding process for monochrome sampled pictures as found in the other profiles is used to decode each colour plane individually as a distinct picture. In addition, a new intra decoding process that can be used by encoders to enable relatively-efficient lossless coding is also added for use when the qpprime_y_zero_transform_bypass_flag syntax element is equal to 1 and QP'Y is equal to 0. In the new High 4:4:4 Predictive profile, the bit depth is also extended up to 14 bits per sample.
In addition to adding the definition of the High 4:4:4 Predictive profile, four other profiles are also specified in this amendment. These profiles, referred to as the High 10 Intra, High 4:2:2 Intra, High 4:4:4 Intra, and CAVLC 4:4:4 Intra profiles, serve to enable applications demanding simple random-access and editing applications with low delay capability. Each of these profiles contains coding capabilities that similar to those of another corresponding profile, except for elimination of support for the decoding processes that involve inter-picture prediction and, in the case of the CAVLC 4:4:4 Intra profile, the additional elimination of support for the CABAC parsing process.
The two added SEI messages are the post-filter hint SEI message and the tone mapping information SEI message. The post-filter hint SEI message provides the coefficients of a post-filter or correlation information for the design of a post-filter for potential use in post-processing of the output decoded pictures to obtain improved displayed quality. The tone mapping information SEI message provides information to enable remapping of the colour samples of the output decoded pictures for customization to particular display environments.