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sse2 version of CollectHistogram()

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~3% faster encoding.

Patch by Christian Duvivier (cduvivier at google dot com)

Change-Id: I8c11d63d0cffb35e145fe0ea74cb66a53f4950d9
This commit is contained in:
Pascal Massimino
2011-04-28 17:00:22 -07:00
parent c1c728d617
commit d757523889
4 changed files with 127 additions and 53 deletions
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44
src/enc/dsp.c
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@ -16,6 +16,48 @@
extern "C" {
#endif
//-----------------------------------------------------------------------------
// Compute susceptibility based on DCT-coeff histograms:
// the higher, the "easier" the macroblock is to compress.
static int ClipAlpha(int alpha) {
return alpha < 0 ? 0 : alpha > 255 ? 255 : alpha;
}
static int GetAlpha(const int histo[MAX_COEFF_THRESH]) {
int num = 0, den = 0, val = 0;
int k;
int alpha;
for (k = 0; k < MAX_COEFF_THRESH; ++k) {
if (histo[k]) {
val += histo[k];
num += val * (k + 1);
den += (k + 1) * (k + 1);
}
}
// we scale the value to a usable [0..255] range
alpha = den ? 10 * num / den - 5 : 0;
return ClipAlpha(alpha);
}
static int CollectHistogram(const uint8_t* ref, const uint8_t* pred,
int start_block, int end_block) {
int histo[MAX_COEFF_THRESH] = { 0 };
int16_t out[16];
int j, k;
for (j = start_block; j < end_block; ++j) {
VP8FTransform(ref + VP8Scan[j], pred + VP8Scan[j], out);
for (k = 0; k < 16; ++k) {
const int v = abs(out[k]) >> 2;
if (v) {
const int bin = (v > MAX_COEFF_THRESH) ? MAX_COEFF_THRESH : v;
histo[bin - 1]++;
}
}
}
return GetAlpha(histo);
}
//-----------------------------------------------------------------------------
// run-time tables (~4k)
@ -657,6 +699,7 @@ VP8CPUInfo VP8GetCPUInfo = NULL;
// Speed-critical function pointers. We have to initialize them to the default
// implementations within VP8EncDspInit().
VP8CHisto VP8CollectHistogram;
VP8Idct VP8ITransform;
VP8Fdct VP8FTransform;
VP8WHT VP8ITransformWHT;
@ -681,6 +724,7 @@ void VP8EncDspInit(void) {
InitTables();
// default C implementations
VP8CollectHistogram = CollectHistogram;
VP8ITransform = ITransform;
VP8FTransform = FTransform;
VP8ITransformWHT = ITransformWHT;