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Merge "Convert VP8LFastSLog2 to fixed point" into main

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This commit is contained in:
Vincent Rabaud
2024-07-10 21:52:39 +00:00
committed by Gerrit Code Review
parent 4838611f91 fb444b692b
commit d27d246e42
7 changed files with 128 additions and 260 deletions
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8
src/enc/histogram_enc.c
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@ -229,8 +229,6 @@ void VP8LHistogramAddSinglePixOrCopy(VP8LHistogram* const histo,
static WEBP_INLINE uint64_t BitsEntropyRefine(const VP8LBitEntropy* entropy) {
uint64_t mix;
const uint64_t fixed_point_entropy =
(uint64_t)(entropy->entropy * (1ll << LOG_2_PRECISION_BITS) + .5);
if (entropy->nonzeros < 5) {
if (entropy->nonzeros <= 1) {
return 0;
@ -240,7 +238,7 @@ static WEBP_INLINE uint64_t BitsEntropyRefine(const VP8LBitEntropy* entropy) {
// distributions of these are combined.
if (entropy->nonzeros == 2) {
return DivRound(99 * ((uint64_t)entropy->sum << LOG_2_PRECISION_BITS) +
fixed_point_entropy,
entropy->entropy,
100);
}
// No matter what the entropy says, we cannot be better than min_limit
@ -260,8 +258,8 @@ static WEBP_INLINE uint64_t BitsEntropyRefine(const VP8LBitEntropy* entropy) {
uint64_t min_limit = (uint64_t)(2 * entropy->sum - entropy->max_val)
<< LOG_2_PRECISION_BITS;
min_limit =
DivRound(mix * min_limit + (1000 - mix) * fixed_point_entropy, 1000);
return (fixed_point_entropy < min_limit) ? min_limit : fixed_point_entropy;
DivRound(mix * min_limit + (1000 - mix) * entropy->entropy, 1000);
return (entropy->entropy < min_limit) ? min_limit : entropy->entropy;
}
}

7
src/enc/predictor_enc.c
View File

@ -57,7 +57,9 @@ static float PredictionCostSpatialHistogram(
// Compute the new cost if 'tile' is added to 'accumulate' but also add the
// cost of the current histogram to guide the spatial predictor selection.
// Basically, favor low entropy, locally and globally.
retval += VP8LCombinedShannonEntropy(&tile[i * 256], &accumulated[i * 256]);
retval += (float)VP8LCombinedShannonEntropy(&tile[i * 256],
&accumulated[i * 256]) /
(1ll << LOG_2_PRECISION_BITS);
}
// Favor keeping the areas locally similar.
if (mode == left_mode) retval -= kSpatialPredictorBias;
@ -541,7 +543,8 @@ static float PredictionCostCrossColor(const uint32_t accumulated[256],
// Favor low entropy, locally and globally.
// Favor small absolute values for PredictionCostSpatial
static const float kExpValue = 2.4f;
return VP8LCombinedShannonEntropy(counts, accumulated) +
return (float)VP8LCombinedShannonEntropy(counts, accumulated) /
(1ll << LOG_2_PRECISION_BITS) +
PredictionCostBias(counts, 3, kExpValue);
}