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lossless: encoding, don't compute unnecessary histo

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share the computation between different modes

3-5 % speedup for lossless alpha
1 % for lossy alpha

no change in compression density

Change-Id: I5e31413b3efcd4319121587da8320ac4f14550b2
This commit is contained in:
Jyrki Alakuijala
2015-06-18 14:54:33 +00:00
committed by James Zern
parent d92453f381
commit 85b44d8a69
3 changed files with 106 additions and 39 deletions
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16
src/dsp/lossless_enc.c
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@ -473,8 +473,8 @@ static WEBP_INLINE double BitsEntropyRefine(int nonzeros, int sum, int max_val,
// Returns the entropy for the symbols in the input array.
// Also sets trivial_symbol to the code value, if the array has only one code
// value. Otherwise, set it to VP8L_NON_TRIVIAL_SYM.
static double BitsEntropy(const uint32_t* const array, int n,
uint32_t* const trivial_symbol) {
double VP8LBitsEntropy(const uint32_t* const array, int n,
uint32_t* const trivial_symbol) {
double retval = 0.;
uint32_t sum = 0;
uint32_t nonzero_code = VP8L_NON_TRIVIAL_SYM;
@ -555,7 +555,7 @@ static double HuffmanCostCombined(const uint32_t* const X,
double VP8LPopulationCost(const uint32_t* const population, int length,
uint32_t* const trivial_sym) {
return
BitsEntropy(population, length, trivial_sym) +
VP8LBitsEntropy(population, length, trivial_sym) +
HuffmanCost(population, length);
}
@ -579,12 +579,12 @@ double VP8LHistogramEstimateBits(const VP8LHistogram* const p) {
double VP8LHistogramEstimateBitsBulk(const VP8LHistogram* const p) {
return
BitsEntropy(p->literal_, VP8LHistogramNumCodes(p->palette_code_bits_),
VP8LBitsEntropy(p->literal_, VP8LHistogramNumCodes(p->palette_code_bits_),
NULL)
+ BitsEntropy(p->red_, NUM_LITERAL_CODES, NULL)
+ BitsEntropy(p->blue_, NUM_LITERAL_CODES, NULL)
+ BitsEntropy(p->alpha_, NUM_LITERAL_CODES, NULL)
+ BitsEntropy(p->distance_, NUM_DISTANCE_CODES, NULL)
+ VP8LBitsEntropy(p->red_, NUM_LITERAL_CODES, NULL)
+ VP8LBitsEntropy(p->blue_, NUM_LITERAL_CODES, NULL)
+ VP8LBitsEntropy(p->alpha_, NUM_LITERAL_CODES, NULL)
+ VP8LBitsEntropy(p->distance_, NUM_DISTANCE_CODES, NULL)
+ VP8LExtraCost(p->literal_ + NUM_LITERAL_CODES, NUM_LENGTH_CODES)
+ VP8LExtraCost(p->distance_, NUM_DISTANCE_CODES);
}