ffmpeg/libswresample/dither_template.c

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/*
* 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
*/
#if defined(TEMPLATE_DITHER_DBL)
# define RENAME(N) N ## _double
# define DELEM double
# define CLIP(v) while(0)
#elif defined(TEMPLATE_DITHER_FLT)
# define RENAME(N) N ## _float
# define DELEM float
# define CLIP(v) while(0)
#elif defined(TEMPLATE_DITHER_S32)
# define RENAME(N) N ## _int32
# define DELEM int32_t
# define CLIP(v) v = FFMAX(FFMIN(v, INT32_MAX), INT32_MIN)
#elif defined(TEMPLATE_DITHER_S16)
# define RENAME(N) N ## _int16
# define DELEM int16_t
# define CLIP(v) v = FFMAX(FFMIN(v, INT16_MAX), INT16_MIN)
#else
ERROR
#endif
void RENAME(swri_noise_shaping)(SwrContext *s, AudioData *dsts, const AudioData *srcs, const AudioData *noises, int count){
int pos = s->dither.ns_pos;
int i, j, ch;
int taps = s->dither.ns_taps;
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];
DELEM *dst = (DELEM*)dsts->ch[ch];
float *ns_errors = s->dither.ns_errors[ch];
const float *ns_coeffs = s->dither.ns_coeffs;
pos = s->dither.ns_pos;
for (i=0; i<count; i++) {
double d1, d = src[i]*S_1;
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]);
ns_errors[pos + taps] = ns_errors[pos] = d1 - d;
d1 *= S;
CLIP(d1);
dst[i] = d1;
}
}
s->dither.ns_pos = pos;
}
#undef RENAME
#undef DELEM
#undef CLIP