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