CPC H04N 19/70 (2014.11) [H04N 19/105 (2014.11); H04N 19/187 (2014.11); H04N 19/46 (2014.11)] | 20 Claims |
1. A method of video processing, comprising:
performing a conversion between a video comprising a plurality of video layers and a bitstream of the video,
wherein the bitstream comprises a plurality of output layer sets (OLSs), each of which comprises one or more of the plurality of video layers, and the bitstream conforms to a format rule,
wherein the format rule specifies that, for a layer i, where i is an integer, the bitstream includes a set of first syntax elements which is used to derive a first variable indicating whether the layer i is used as an output layer in at least one of the plurality of OLSs,
wherein the format rule further specifies that the bitstream includes a set of third syntax elements which is used to derive a second variable indicating whether the layer i is used as a reference layer for at least one of the plurality of video layers, and wherein the format rule disallows values of the first variable and the second variable both equal to 0, and
wherein disallowing the values of the first variable and the second variable both equal to 0 indicates that no layer that is neither a direct reference layer of any other layer nor an output layer of at least one OLS.
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