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Merge "Move DitherCombine8x8 to dsp/dec.c"

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This commit is contained in:
Pascal Massimino
2016-05-27 05:55:04 +00:00
committed by Gerrit Code Review
parent 77cad88589 77f21c9c39
commit 0b8ae8520f
3 changed files with 40 additions and 19 deletions
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28
src/dec/frame.c
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@ -316,6 +316,9 @@ static void PrecomputeFilterStrengths(VP8Decoder* const dec) {
//------------------------------------------------------------------------------
// Dithering
// minimal amp that will provide a non-zero dithering effect
#define MIN_DITHER_AMP 4
#define DITHER_AMP_TAB_SIZE 12
static const int kQuantToDitherAmp[DITHER_AMP_TAB_SIZE] = {
// roughly, it's dqm->uv_mat_[1]
@ -356,27 +359,14 @@ void VP8InitDithering(const WebPDecoderOptions* const options,
}
}
// minimal amp that will provide a non-zero dithering effect
#define MIN_DITHER_AMP 4
#define DITHER_DESCALE 4
#define DITHER_DESCALE_ROUNDER (1 << (DITHER_DESCALE - 1))
#define DITHER_AMP_BITS 8
#define DITHER_AMP_CENTER (1 << DITHER_AMP_BITS)
// Convert to range: [-2,2] for dither=50, [-4,4] for dither=100
static void Dither8x8(VP8Random* const rg, uint8_t* dst, int bps, int amp) {
int i, j;
for (j = 0; j < 8; ++j) {
for (i = 0; i < 8; ++i) {
// TODO: could be made faster with SSE2
const int bits =
VP8RandomBits2(rg, DITHER_AMP_BITS + 1, amp) - DITHER_AMP_CENTER;
// Convert to range: [-2,2] for dither=50, [-4,4] for dither=100
const int delta = (bits + DITHER_DESCALE_ROUNDER) >> DITHER_DESCALE;
const int v = (int)dst[i] + delta;
dst[i] = (v < 0) ? 0 : (v > 255) ? 255u : (uint8_t)v;
}
dst += bps;
uint8_t dither[64];
int i;
for (i = 0; i < 8 * 8; ++i) {
dither[i] = VP8RandomBits2(rg, VP8_DITHER_AMP_BITS + 1, amp);
}
VP8DitherCombine8x8(dither, dst, bps);
}
static void DitherRow(VP8Decoder* const dec) {