ffmpeg/libswresample/dither_template.c

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#if defined(TEMPLATE_DITHER_DBL)
# define RENAME(N) N ## _double
# define DELEM double
# define CLIP(v)
#elif defined(TEMPLATE_DITHER_FLT)
# define RENAME(N) N ## _float
# define DELEM float
# define CLIP(v)
#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 *srcs, AudioData *noises, int count){
int i, j, pos, ch;
int taps = s->dither.ns_taps;
float S = s->dither.ns_scale;
float S_1 = s->dither.ns_scale_1;
for (ch=0; ch<srcs->ch_count; ch++) {
const float *noise = ((const float *)noises->ch[ch]) + s->dither.dither_pos;
DELEM *data = (DELEM*)srcs->ch[ch];
pos = s->dither.ns_pos;
for (i=0; i<count; i++) {
double d1, d = data[i];
for(j=0; j<taps; j++)
d -= s->dither.ns_coeffs[j] * s->dither.ns_errors[ch][pos + j];
pos = pos ? pos - 1 : pos - 1 + taps;
d1 = rint((d + noise[i]) * S_1)*S;
s->dither.ns_errors[ch][pos + taps] = s->dither.ns_errors[ch][pos] = d1 - d;
CLIP(d1);
data[i] = d1;
}
}
s->dither.ns_pos = pos;
}
#undef RENAME
#undef DELEM
#undef CLIP