[x265] [PATCH] Fix weighted prediction delta_chroma_offset non-conformance

[Richard]

From ac54e3ab6b5cbbd44129c2c2087dc87f963cfdea Mon Sep 17 00:00:00 2001
 From: Mr-Z-2697 <74594146+Mr-Z-2697 at users.noreply.github.com>
 Date: Mon, 12 May 2025 01:58:02 +0800
 Subject: [PATCH] Fix weighted prediction delta_chroma_offset non-conformance
 
 The calculation here is the same as final entropy coding.
 Specification says the valid range is [-512, 511].
 ---
  source/encoder/weightPrediction.cpp | 6 +++++-
  1 file changed, 5 insertions(+), 1 deletion(-)
 
 diff --git a/source/encoder/weightPrediction.cpp b/source/encoder/weightPrediction.cpp
 index bc842f173..fd010d032 100644
 --- a/source/encoder/weightPrediction.cpp
 +++ b/source/encoder/weightPrediction.cpp
 @@ -466,7 +466,11 @@ void weightAnalyse(Slice& slice, Frame& frame, x265_param& param)
                  }
              }
  
 -            if (!bFound || (minscale == (1 << mindenom) && minoff == 0) || (float)minscore / origscore > 0.998f)
 +            int predTemp = (128 - ((128 * minscale) >> (mindenom)));
 +            int deltaChromaTemp = minoff - predTemp;
 +
 +            if (!bFound || (minscale == (1 << mindenom) && minoff == 0) || (float)minscore / origscore > 0.998f ||
 +                (plane && (deltaChromaTemp < -512 || deltaChromaTemp > 511)) )
              {
                  SET_WEIGHT(weights[plane], false, 1 << denom, denom, 0);
              }
 -- 
 2.49.0
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