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Provide an SSE2 implementation of CombinedShannonEntropy.

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CombinedShannonEntropy takes 30% for lossless compression.
This implementation speeds up the overall process by 2 to 3 %.

Change-Id: I04a71743284c38814fd0726034d51a02b1b6ba8f
This commit is contained in:
Vincent Rabaud
2015-12-11 15:12:19 +01:00
parent 04507dc91f
commit 2835089d6a
3 changed files with 86 additions and 6 deletions
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14
src/dsp/lossless_enc.c
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@ -413,15 +413,15 @@ static float CombinedShannonEntropy(const int X[256], const int Y[256]) {
int sumX = 0, sumXY = 0;
for (i = 0; i < 256; ++i) {
const int x = X[i];
const int xy = x + Y[i];
if (x != 0) {
const int xy = x + Y[i];
sumX += x;
retval -= VP8LFastSLog2(x);
sumXY += xy;
retval -= VP8LFastSLog2(xy);
} else if (xy != 0) {
sumXY += xy;
retval -= VP8LFastSLog2(xy);
} else if (Y[i] != 0) {
sumXY += Y[i];
retval -= VP8LFastSLog2(Y[i]);
}
}
retval += VP8LFastSLog2(sumX) + VP8LFastSLog2(sumXY);
@ -435,7 +435,7 @@ static float PredictionCostSpatialHistogram(const int accumulated[4][256],
for (i = 0; i < 4; ++i) {
const double kExpValue = 0.94;
retval += PredictionCostSpatial(tile[i], 1, kExpValue);
retval += CombinedShannonEntropy(tile[i], accumulated[i]);
retval += VP8LCombinedShannonEntropy(tile[i], accumulated[i]);
}
return (float)retval;
}
@ -894,7 +894,7 @@ static float PredictionCostCrossColor(const int accumulated[256],
// Favor low entropy, locally and globally.
// Favor small absolute values for PredictionCostSpatial
static const double kExpValue = 2.4;
return CombinedShannonEntropy(counts, accumulated) +
return VP8LCombinedShannonEntropy(counts, accumulated) +
PredictionCostSpatial(counts, 3, kExpValue);
}
@ -1269,6 +1269,7 @@ VP8LFastLog2SlowFunc VP8LFastSLog2Slow;
VP8LCostFunc VP8LExtraCost;
VP8LCostCombinedFunc VP8LExtraCostCombined;
VP8LCombinedShannonEntropyFunc VP8LCombinedShannonEntropy;
VP8LCostCountFunc VP8LHuffmanCostCount;
@ -1300,6 +1301,7 @@ WEBP_TSAN_IGNORE_FUNCTION void VP8LEncDspInit(void) {
VP8LExtraCost = ExtraCost;
VP8LExtraCostCombined = ExtraCostCombined;
VP8LCombinedShannonEntropy = CombinedShannonEntropy;
VP8LHuffmanCostCount = HuffmanCostCount;