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simplify the Histogram struct, to only store max_value and last_nz

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we don't need to store the whole distribution in order to compute the alpha

Later, we can incorporate the max_value / last_non_zero bookkeeping
in SSE2 directly.

Change-Id: I748ccea4ac17965d7afcab91845ef01be3aa3e15
This commit is contained in:
Pascal Massimino
2014-12-10 10:44:57 +01:00
parent 37e395fd1c
commit bad775715a
6 changed files with 59 additions and 33 deletions
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17
src/dsp/dsp.h
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@ -151,13 +151,22 @@ typedef int (*VP8QuantizeBlockWHT)(int16_t in[16], int16_t out[16],
const struct VP8Matrix* const mtx);
extern VP8QuantizeBlockWHT VP8EncQuantizeBlockWHT;
// Collect histogram for susceptibility calculation and accumulate in histo[].
struct VP8Histogram;
extern const int VP8DspScan[16 + 4 + 4];
// Collect histogram for susceptibility calculation.
#define MAX_COEFF_THRESH 31 // size of histogram used by CollectHistogram.
typedef struct {
// We only need to store max_value and last_non_zero, not the distribution.
int max_value;
int last_non_zero;
} VP8Histogram;
typedef void (*VP8CHisto)(const uint8_t* ref, const uint8_t* pred,
int start_block, int end_block,
struct VP8Histogram* const histo);
extern const int VP8DspScan[16 + 4 + 4];
VP8Histogram* const histo);
extern VP8CHisto VP8CollectHistogram;
// General-purpose util function to help VP8CollectHistogram().
void VP8LSetHistogramData(const int distribution[MAX_COEFF_THRESH + 1],
VP8Histogram* const histo);
// must be called before using any of the above
WEBP_TSAN_IGNORE_FUNCTION void VP8EncDspInit(void);