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Faster alpha coding for webp

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No significant size degradation (+0.001 %) for 1000 image corpus

Fixes the 8 ms vs 2 ms degradation from:
"lossless: 0.37 % compression density improvement"

Change-Id: Id540169a305d9d5c6213a82b46c879761b3ca608
This commit is contained in:
Jyrki Alakuijala 2015-06-16 13:05:20 +00:00 committed by James Zern
parent 5e75642efd
commit 2cce031704
1 changed files with 6 additions and 4 deletions
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10
src/enc/vp8l.c
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@ -289,6 +289,12 @@ static int AnalyzeAndInit(VP8LEncoder* const enc) {
enc->use_palette_ =
AnalyzeAndCreatePalette(pic, enc->palette_, &enc->palette_size_);
// TODO(jyrki): replace the decision to be based on an actual estimate
// of entropy, or even spatial variance of entropy.
enc->histo_bits_ = GetHistoBits(method, enc->use_palette_,
pic->width, pic->height);
enc->transform_bits_ = GetTransformBits(method, enc->histo_bits_);
if (low_effort) {
// AnalyzeEntropy is somewhat slow.
enc->use_predict_ = !enc->use_palette_;
@ -316,10 +322,6 @@ static int AnalyzeAndInit(VP8LEncoder* const enc) {
enc->use_cross_color_ = enc->use_predict_ =
(min_entropy_ix == kSpatial) || (min_entropy_ix == kSpatialSubGreen);
}
// Evaluate histogram bits based on the original value of use_palette flag.
enc->histo_bits_ = GetHistoBits(method, enc->use_palette_, pic->width,
pic->height);
enc->transform_bits_ = GetTransformBits(method, enc->histo_bits_);
if (!VP8LHashChainInit(&enc->hash_chain_, pix_cnt)) return 0;