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factorize and unify GetAlpha() between the C and SSE2 version

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patch by Christian Duvivier (cduvivier at google dot com)

Change-Id: I47ac75010aa4036cf09f13d23043e654c4966a00
This commit is contained in:
Pascal Massimino 2011-05-04 16:26:47 -07:00
parent 6d0e66c23e
commit 8dfc4c6f17
3 changed files with 18 additions and 24 deletions
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24
src/enc/dsp.c
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@ -24,13 +24,14 @@ static int ClipAlpha(int alpha) {
return alpha < 0 ? 0 : alpha > 255 ? 255 : alpha;
}
static int GetAlpha(const int histo[MAX_COEFF_THRESH]) {
int VP8GetAlpha(const int histo[MAX_COEFF_THRESH + 1]) {
int num = 0, den = 0, val = 0;
int k;
int alpha;
// note: changing this loop to avoid the numerous "k + 1" slows things down.
for (k = 0; k < MAX_COEFF_THRESH; ++k) {
if (histo[k]) {
val += histo[k];
if (histo[k + 1]) {
val += histo[k + 1];
num += val * (k + 1);
den += (k + 1) * (k + 1);
}
@ -42,20 +43,25 @@ static int GetAlpha(const int histo[MAX_COEFF_THRESH]) {
static int CollectHistogram(const uint8_t* ref, const uint8_t* pred,
int start_block, int end_block) {
int histo[MAX_COEFF_THRESH] = { 0 };
int histo[MAX_COEFF_THRESH + 1] = { 0 };
int16_t out[16];
int j, k;
for (j = start_block; j < end_block; ++j) {
VP8FTransform(ref + VP8Scan[j], pred + VP8Scan[j], out);
// Convert coefficients to bin (within 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]++;
}
out[k] = (v > MAX_COEFF_THRESH) ? MAX_COEFF_THRESH : v;
}
// Use bin to update histogram.
for (k = 0; k < 16; ++k) {
histo[out[k]]++;
}
}
return GetAlpha(histo);
return VP8GetAlpha(histo);
}
//-----------------------------------------------------------------------------

16
src/enc/dsp_sse2.c
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@ -61,21 +61,7 @@ static int CollectHistogramSSE2(const uint8_t* ref, const uint8_t* pred,
}
}
{
int num = 0, den = 0, val = 0;
int alpha;
for (k = 0; k < MAX_COEFF_THRESH; ++k) {
if (histo[k + 1]) {
val += histo[k + 1];
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;
alpha = alpha < 0 ? 0 : alpha > 255 ? 255 : alpha;
return alpha;
}
return VP8GetAlpha(histo);
}
//-----------------------------------------------------------------------------

2
src/enc/vp8enci.h
View File

@ -446,6 +446,8 @@ int VP8EncFinishLayer(VP8Encoder* const enc); // finalize coding
void VP8EncDeleteLayer(VP8Encoder* enc); // reclaim memory
// in dsp.c
int VP8GetAlpha(const int histo[MAX_COEFF_THRESH + 1]);
// Transforms
// VP8Idct: Does one of two inverse transforms. If do_two is set, the transforms
// will be done for (ref, in, dst) and (ref + 4, in + 16, dst + 4).