/* * 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); }