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/*
* Copyright (C) 2012 Michael Niedermayer (michaelni@gmx.at)
*
* This file is part of libswresample
*
* libswresample is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* libswresample is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with libswresample; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/avassert.h"
#include "swresample_internal.h"
void swri_get_dither(SwrContext *s, void *dst, int len, unsigned seed, enum AVSampleFormat out_fmt, enum AVSampleFormat in_fmt) {
double scale = 0;
#define TMP_EXTRA 2
double *tmp = av_malloc((len + TMP_EXTRA) * sizeof(double));
int i;
if(in_fmt == AV_SAMPLE_FMT_FLT || in_fmt == AV_SAMPLE_FMT_DBL){
if(out_fmt == AV_SAMPLE_FMT_S32) scale = 1.0/(1L<<31);
if(out_fmt == AV_SAMPLE_FMT_S16) scale = 1.0/(1L<<15);
if(out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1.0/(1L<< 7);
}
if(in_fmt == AV_SAMPLE_FMT_S32 && out_fmt == AV_SAMPLE_FMT_S16) scale = 1L<<16;
if(in_fmt == AV_SAMPLE_FMT_S32 && out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1L<<24;
if(in_fmt == AV_SAMPLE_FMT_S16 && out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1L<<8;
scale *= s->dither_scale;
for(i=0; i<len + TMP_EXTRA; i++){
double v;
seed = seed* 1664525 + 1013904223;
switch(s->dither_method){
case SWR_DITHER_RECTANGULAR: v= ((double)seed) / UINT_MAX - 0.5; break;
case SWR_DITHER_TRIANGULAR :
case SWR_DITHER_TRIANGULAR_HIGHPASS :
v = ((double)seed) / UINT_MAX;
seed = seed*1664525 + 1013904223;
v-= ((double)seed) / UINT_MAX;
break;
default: av_assert0(0);
}
tmp[i] = v;
}
for(i=0; i<len; i++){
double v;
switch(s->dither_method){
case SWR_DITHER_RECTANGULAR:
case SWR_DITHER_TRIANGULAR :
v = tmp[i];
break;
case SWR_DITHER_TRIANGULAR_HIGHPASS :
v = (- tmp[i] + 2*tmp[i+1] - tmp[i+2]) / sqrt(6);
break;
default: av_assert0(0);
}
v*= scale;
switch(in_fmt){
case AV_SAMPLE_FMT_S16: ((int16_t*)dst)[i] = v; break;
case AV_SAMPLE_FMT_S32: ((int32_t*)dst)[i] = v; break;
case AV_SAMPLE_FMT_FLT: ((float *)dst)[i] = v; break;
case AV_SAMPLE_FMT_DBL: ((double *)dst)[i] = v; break;
default: av_assert0(0);
}
}
av_free(tmp);
}
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