Changes between Initial Version and Version 1 of Ticket #1114, comment 2
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 30 Jun 2020, 07:43:16 (2 years ago)
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Ticket #1114, comment 2
initial v1 1 1 There will be a mismatch between spec and SW for the RPR case though no issue for the nonRPR case, due to the 2x2 chroma subblock MC manner in the spec. 2 rom eq.(935) and eq.(936), we can find that for the topleft position of each subblock, we keep a precision of 14 bit + 5 bit = 19 bits (14 scaling window + 5 MV), as shown in (935). But for other positions, the calculated precision is 10 bits. That's why we have ( ( Sign( refxSbC ) * ( ( Abs( refxSbC ) + 256 ) >> 9 ) in eq. (936).2 From eq.(935) and eq.(936), we can find that for the topleft position of each subblock, we keep a precision of 14 bit + 5 bit = 19 bits (14 scaling window + 5 MV), as shown in (935). But for other positions, the calculated precision is 10 bits. That's why we have ( ( Sign( refxSbC ) * ( ( Abs( refxSbC ) + 256 ) >> 9 ) in eq. (936). 3 3 As a results of rounding, for a specific position, whether it is calculated as the topleft sample of a subblock, or it is calculated as an inner sample, the results may be different. Attached is an example to show such a difference.