diff options
Diffstat (limited to 'libswresample/dither.c')
| -rw-r--r-- | libswresample/dither.c | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/libswresample/dither.c b/libswresample/dither.c new file mode 100644 index 0000000000..79113f4c23 --- /dev/null +++ b/libswresample/dither.c @@ -0,0 +1,87 @@ +/* + * 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; + + out_fmt = av_get_packed_sample_fmt(out_fmt); + in_fmt = av_get_packed_sample_fmt( in_fmt); + + 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); +} |