JCTVC-O0342 Non-RCE2: Cross-check Results of 16 Bit Intermediate Buffer for HEVC Range Extension (JCTVC-O0233) [K. Kawamura, S. Naito (KDDI)] [late]
JCTVC-O0235 High Precision Weighted Prediction for HEVC Range Extension [W. Pu, J. Chen, M. Karczewicz, W.-S. Kim, J. Sole, L. Guo (Qualcomm)]
(Reviewed Fri 25th morning GJS & JRO)
For HEVC Range Extension, up to 16 bit video is supported. However, in the current HEVC Range Extension working draft, weighted prediction parameters (i.e. weight and offset) are both restricted to 8 bit precision, which may affect coding efficiency due to the lack of enough precision. A high precision weighted prediction is proposed, which extends the precision of the offset parameter. Simulation results show for fading high bit depth sequences, the high precision weighted prediction can achieve average BD-rate reduction of 1.3% and 2.8% for RA and LD-B, respectively, with reportedly almost no computation complexity increment..
Decision (BF): Adopt (with a high_precision_offset_flag at SPS level).
It was remarked that the clipping applied to the chroma offset range should be studied to consider potential need for large offsets, e.g., as the center of the range is ordinarily actually at 128 << (bitdepth − 8). Further study of that is encouraged.
JCTVC-O0336 Cross Check for High Precision Weighted Prediction for HEVC Range Extension [A. Khairat (Fraunhofer HHI)] [late]
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