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speed-up lossless (~3%) with ad-hoc histogram cost evaluation

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* merge cost calculation functions (BitsEntropy() and HuffmanCost())
* have HistogramAdd() specialized into separate functions
* use threshold to bail-out early
* revamp code a bit

* also: save memory by freeing free(histogram_image)

Change-Id: I8ee5d2cfa1462d5d6ea6361f5c89925a3720ef55
This commit is contained in:
skal
2013-03-18 22:34:32 +01:00
parent bb85b43727
commit f4ffb2d59a
3 changed files with 159 additions and 76 deletions
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16
src/enc/histogram.h
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@ -80,22 +80,6 @@ double VP8LHistogramEstimateBits(const VP8LHistogram* const p);
// represent the entropy code itself.
double VP8LHistogramEstimateBitsBulk(const VP8LHistogram* const p);
static WEBP_INLINE void VP8LHistogramAdd(VP8LHistogram* const p,
const VP8LHistogram* const a) {
int i;
for (i = 0; i < PIX_OR_COPY_CODES_MAX; ++i) {
p->literal_[i] += a->literal_[i];
}
for (i = 0; i < NUM_DISTANCE_CODES; ++i) {
p->distance_[i] += a->distance_[i];
}
for (i = 0; i < 256; ++i) {
p->red_[i] += a->red_[i];
p->blue_[i] += a->blue_[i];
p->alpha_[i] += a->alpha_[i];
}
}
static WEBP_INLINE int VP8LHistogramNumCodes(const VP8LHistogram* const p) {
return 256 + NUM_LENGTH_CODES +
((p->palette_code_bits_ > 0) ? (1 << p->palette_code_bits_) : 0);