Joint Collaborative Team on Video Coding (jct-vc) Contribution
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- 7.6.3Colour-related SEI and VUI (3)
- 7.6.4Other SEI (3)
7.6SEI and VUI (9)7.6.1General (1)JCTVC-Q0183 MV-HEVC/SHVC HLS: SEI message cleanups [Hendry, Y.-K. Wang, A. K. Ramasubramonian (Qualcomm)] [late] 7.6.2Overlay-related SEI (2)JCTVC-Q0045 MV-HEVC/SHVC HLS: Proposal for an SEI message on selectable overlays [N. Stefanoski, O. Wang, A. Smolic (DRZ), T. Szypulski (ESPN)] Discussed 31 March p.m. (GJS). In this document, an SEI message is proposed to realize the functionality of selectable overlays. selectable overlays is a functionality which enables viewers to turn on and off single overlay elements, like score bars, information panels, news tickers, etc. on their display device. An SEI message is proposed that describes overlays with three different categories of auxiliary pictures, representing overlay content, overlay label, and overlay alpha information. The syntax is identical to the second option that is proposed in JCTVC-Q0096. This proposal is based on the input documents JCTVC-P0092, JCTVC-P0135, and JCTVC-O0358 and intends to harmonize the designs of the SEI messages proposed in these documents. The selectable overlays functionality was first proposed in JCTVC-O0358 at the 15th JCT-VC meeting (there this functionality was called optional overlays). Auxiliary picture types have been adopted for which the interpretation can be specified by an SEI message. It was proposed to use that approach for the selectable overlays functionality with help of auxiliary pictures. At the last JCT-VC meeting (16th JCT-VC-Meeting in San Jose), two proposals, i.e. JCTVC-P0092 and JCTVC-P0135, were presented that proposed the selectable overlays functionality using auxiliary pictures. When discussed previously, it was recorded that "At the concept level, it was agreed to plan to support such a capability. Further study was needed to work out details." General question: What, in general, is the association between auxiliary pictures and primary pictures? String coding using UTF-8 with null termination was suggested per the scalability information SEI message in AVC (H.263 refers to ISO/IEC 10646 for UTF-8, AVC has a similar reference). It was noted that ISOBMFF has strings with a string type defined and could be studied as an example of how to convey and specify them. It was remarked, and agreed, that this is not essential to delivering SVC or other major projects, and could be considered on a slower schedule if it does not mature sufficiently rapidly. Roughly the same as proposed in Q0096.
Discussed 31 March p.m. (GJS). A new SEI message is proposed to support overlay pictures with individually controllable overlay elements using three categories of auxiliary pictures, representing overlay content, overlay label, and overlay alpha. The proposed SEI message describes the overlays, by indicating the layer_id values of the various aux pic layers, and providing overlay label mapping parameters. Two options are proposed regarding AuxId values. In the first option, a single AuxId value is proposed to be allocated to overlay pictures. In the second option, AuxId values from the already allocated “Unspecified” range are used. The syntax in the second option is identical to that proposed in JCTVC-Q0045. Other related contributions are JCTVC-P0135, JCTVC-O0358, and JCTVC-P0092. In the v2 version of this document, editorial improvements have been made to the semantics of overlay_content_layer_id[ i ]. The argument for allocating a special aux type code to be used with overlays would be to be able to identify at the VPS level (rather than from an SEI message) whether overlays are (or may be) present. Closely related to JCTVC-Q0045, see notes on that contribution. 7.6.3Colour-related SEI and VUI (3)JCTVC-Q0074 SEI message for Colour Mapping Information [P. Andrivon, P. Bordes, E. François (Technicolor)] Discussed Tues pm (GJS). The proposal is to provide information about how to convert the decoded pictures from the colour space in which the decoded pictures are represented to a different colour space – e.g., for use on an alternative display. For example, if the decoded pictures are in the Rec. BT.2020 colour space, the proposal is to provide guidance to perform a better mapping to a more limited colour space such as BT.709 – e.g., performing clipping. The concept was previously discussed in JCTVC-N0180, JCTVC-O0363, JCTVC-P0126. The model is asserted to be compatible with built-in functionality in CE devices. It is stated that software is supplied to identify proposed model parameters. Implementation is provided in HM-13.0+RExt-6.0 encoders and decoders. When the proposed colour mapping information SEI message is present, colour mapping is applied to the decoded output pictures. The proposal is asserted to be similar in concept (and in syntax and semantics) to the current tone mapping SEI message type 3 but extended to support one LUT per channel instead of just one LUT that applies to all three channels, and a matrix is also proposed for cross-component transformation. At the decoder side, the LUT would applied first, followed by the matrix (in the opposite order ordinarily used, e.g. for YUV to RGB to linear conversion). At the previous meeting, some concerns were expressed about editorial quality and persistence aspects. Quote from previous meeting: "Some additional study was requested by some participants, although there was some support for the proposal (at least in concept). No particular problems were identified with the proposal." Q0183 was related regarding persistence and was asserted to have been taken into account. It was remarked that the syntax elements pre_lut_num_pivots_minus1[ c ] and post_lut_num_pivots_minus1[ c ] were proposed to have a very large range of values. The proponent indicated that their testing was done with 33 pivot points. A suggestion was 64 * 2^(bit depth – 8). The proposed syntax was somewhat similar to the prior tone mapping information SEI message. The distinction made here is that the proposed information is more about colour space transformation than about dynamic range transformation. The proponent indicated that RP 177 is a relevant SMPTE recommendation, but the proponent indicated that its use would result in clipping. Further discussed 2 April p.m. (GJS). It was suggested to adopt this into the SHVC draft; however, a final review is anticipated to occur at the next meeting to determine whether it is fully mature or not at that time for final approval (or should wait for a next amendment/revision). Decision: Agreed.
Discussed Tues noon (GJS). Proposes adding precision.
Editorial issues:
JCTVC-Q0084 VUI entries for YZX and digital cinema EOTF [C. Fogg, J. Helman (Movielabs)] Discussed Tues noon (GJS). This contribution suggests changes to address feedback received since the previous meeting in San Jose (January 2014) on the XYZ color description information in HEVC Annex E (video usability information, a.k.a. VUI). In the matrix_coeffs semantics, it is proposed that the YZX mapping from real values to integer follow convention for YCbCr and GBR signals for both video_full_range_flag=0 and video_full_range_flag=1. A transfer_characteristics code point for digital cinema EOTF (with gamma 2.6) is also requested. Technical actions:
Editorial actions:
Decision: Adopted (RExt). (Confirmed 2 April p.m. GJS.)Recommend adoption with refinements as described above. 7.6.4Other SEI (3)JCTVC-Q0090 HEVC/MV-HEVC/SHVC HLS: Redundant picture SEI message [M. Sychev, V. Stepin, S. Ikonin (Huawei)] JCTVC-Q0164 MV-HEVC/SHVC HLS: On sub-bitstream property SEI [T. Ikai, T. Yamamoto, T. Tsukuba (Sharp)] JCTVC-Q0167 MV-HEVC/SHVC HLS: On layers not present SEI [T. Ikai (Sharp)] Yüklə 0,82 Mb. Dostları ilə paylaş:
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