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Unify some entropy functions.

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The code and logic is unified when computing bit entropy + Huffman cost.

Speed-wise, we gain 8% for lossless encoding.
Logic-wise, the beginning/end of the distributions are handled properly
and the compression ratio does not change much.

Change-Id: Ifa91d7d3e667c9a9a421faec4e845ecb6479a633
This commit is contained in:
Vincent Rabaud
2015-12-17 16:25:34 +01:00
parent ba7f4b68c9
commit ca509a3362
4 changed files with 107 additions and 142 deletions
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25
src/dsp/lossless.h
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@ -208,12 +208,9 @@ typedef struct { // small struct to hold counters
int streaks[2][2]; // [zero/non-zero][streak<3 / streak>=3]
} VP8LStreaks;
typedef VP8LStreaks (*VP8LCostCountFunc)(const uint32_t* population,
int length);
typedef VP8LStreaks (*VP8LCostCombinedCountFunc)(const uint32_t* X,
const uint32_t* Y, int length);
extern VP8LCostCountFunc VP8LHuffmanCostCount;
extern VP8LCostCombinedCountFunc VP8LHuffmanCostCombinedCount;
typedef struct { // small struct to hold bit entropy results
@ -226,14 +223,28 @@ typedef struct { // small struct to hold bit entropy results
void VP8LBitEntropyInit(VP8LBitEntropy* const entropy);
// Get the combined symbol entropy for the distributions 'X' and 'Y'.
// Get the combined symbol bit entropy and Huffman cost stats for the
// distributions 'X' and 'Y'. Those results can then be refined according to
// codec specific heuristics.
void VP8LGetCombinedEntropyUnrefined(const uint32_t* const X,
const uint32_t* const Y, int length,
VP8LBitEntropy* bit_entropy,
VP8LStreaks* stats);
VP8LBitEntropy* const bit_entropy,
VP8LStreaks* const stats);
// Get the entropy for the distribution 'X'.
void VP8LGetEntropyUnrefined(const uint32_t* const X, int length,
VP8LBitEntropy* const bit_entropy,
VP8LStreaks* const stats);
void VP8LBitsEntropyUnrefined(const uint32_t* const array, int n,
VP8LBitEntropy* entropy);
VP8LBitEntropy* const entropy);
typedef void (*GetEntropyUnrefinedHelperFunc)(uint32_t val, int i,
uint32_t* const val_prev,
int* const i_prev,
VP8LBitEntropy* const bit_entropy,
VP8LStreaks* const stats);
// Internal function used by VP8LGet*EntropyUnrefined.
extern GetEntropyUnrefinedHelperFunc VP8LGetEntropyUnrefinedHelper;
typedef void (*VP8LHistogramAddFunc)(const VP8LHistogram* const a,
const VP8LHistogram* const b,