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swr: work with 4 noise shaping coeffs at a time 

63->38 kcycles

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2013-01-12 19:11:08 +01:00
parent 93bc0f0180
commit c8737d348b
1 changed files with 10 additions and 1 deletions
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11
libswresample/dither_template.c
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@ -29,6 +29,9 @@ void RENAME(swri_noise_shaping)(SwrContext *s, AudioData *dsts, const AudioData
float S = s->dither.ns_scale;
float S_1 = s->dither.ns_scale_1;
av_assert2((taps&3) != 2);
av_assert2((taps&3) != 3 || s->dither.ns_coeffs[taps] == 0);
for (ch=0; ch<srcs->ch_count; ch++) {
const float *noise = ((const float *)noises->ch[ch]) + s->dither.noise_pos;
const DELEM *src = (const DELEM*)srcs->ch[ch];
@ -38,7 +41,13 @@ void RENAME(swri_noise_shaping)(SwrContext *s, AudioData *dsts, const AudioData
pos = s->dither.ns_pos;
for (i=0; i<count; i++) {
double d1, d = src[i]*S_1;
for(j=0; j<taps; j++)
for(j=0; j<taps-2; j+=4) {
d -= ns_coeffs[j ] * ns_errors[pos + j ]
+ns_coeffs[j + 1] * ns_errors[pos + j + 1]
+ns_coeffs[j + 2] * ns_errors[pos + j + 2]
+ns_coeffs[j + 3] * ns_errors[pos + j + 3];
}
if(j < taps)
d -= ns_coeffs[j] * ns_errors[pos + j];
pos = pos ? pos - 1 : taps - 1;
d1 = rint(d + noise[i]);