| /* |
| * 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); |
| } |