2 * Copyright (C) 2012-2013 Michael Niedermayer (michaelni@gmx.at)
4 * This file is part of libswresample
6 * libswresample is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * libswresample is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with libswresample; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 #include "libavutil/avassert.h"
22 #include "swresample_internal.h"
24 #include "noise_shaping_data.c"
26 void swri_get_dither(SwrContext *s, void *dst, int len, unsigned seed, enum AVSampleFormat noise_fmt) {
27 double scale = s->dither.noise_scale;
29 double *tmp = av_malloc((len + TMP_EXTRA) * sizeof(double));
32 for(i=0; i<len + TMP_EXTRA; i++){
34 seed = seed* 1664525 + 1013904223;
36 switch(s->dither.method){
37 case SWR_DITHER_RECTANGULAR: v= ((double)seed) / UINT_MAX - 0.5; break;
39 av_assert0(s->dither.method < SWR_DITHER_NB);
40 v = ((double)seed) / UINT_MAX;
41 seed = seed*1664525 + 1013904223;
42 v-= ((double)seed) / UINT_MAX;
51 switch(s->dither.method){
53 av_assert0(s->dither.method < SWR_DITHER_NB);
56 case SWR_DITHER_TRIANGULAR_HIGHPASS :
57 v = (- tmp[i] + 2*tmp[i+1] - tmp[i+2]) / sqrt(6);
64 case AV_SAMPLE_FMT_S16P: ((int16_t*)dst)[i] = v; break;
65 case AV_SAMPLE_FMT_S32P: ((int32_t*)dst)[i] = v; break;
66 case AV_SAMPLE_FMT_FLTP: ((float *)dst)[i] = v; break;
67 case AV_SAMPLE_FMT_DBLP: ((double *)dst)[i] = v; break;
68 default: av_assert0(0);
75 int swri_dither_init(SwrContext *s, enum AVSampleFormat out_fmt, enum AVSampleFormat in_fmt)
80 if (s->dither.method > SWR_DITHER_TRIANGULAR_HIGHPASS && s->dither.method <= SWR_DITHER_NS)
81 return AVERROR(EINVAL);
83 out_fmt = av_get_packed_sample_fmt(out_fmt);
84 in_fmt = av_get_packed_sample_fmt( in_fmt);
86 if(in_fmt == AV_SAMPLE_FMT_FLT || in_fmt == AV_SAMPLE_FMT_DBL){
87 if(out_fmt == AV_SAMPLE_FMT_S32) scale = 1.0/(1L<<31);
88 if(out_fmt == AV_SAMPLE_FMT_S16) scale = 1.0/(1L<<15);
89 if(out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1.0/(1L<< 7);
91 if(in_fmt == AV_SAMPLE_FMT_S32 && out_fmt == AV_SAMPLE_FMT_S16) scale = 1L<<16;
92 if(in_fmt == AV_SAMPLE_FMT_S32 && out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1L<<24;
93 if(in_fmt == AV_SAMPLE_FMT_S16 && out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1L<<8;
95 scale *= s->dither.scale;
98 s->dither.noise_scale= scale;
99 s->dither.ns_scale = scale;
100 s->dither.ns_scale_1 = 1/scale;
101 memset(s->dither.ns_errors, 0, sizeof(s->dither.ns_errors));
102 for (i=0; filters[i].coefs; i++) {
103 const filter_t *f = &filters[i];
104 if (fabs(s->out_sample_rate - f->rate) / f->rate <= .05 && f->name == s->dither.method) {
106 s->dither.ns_taps = f->len;
107 for (j=0; j<f->len; j++)
108 s->dither.ns_coeffs[j] = f->coefs[j];
109 s->dither.ns_scale_1 *= 1 - exp(f->gain_cB * M_LN10 * 0.005) * 2 / (1<<(8*av_get_bytes_per_sample(out_fmt)));
113 if (!filters[i].coefs && s->dither.method > SWR_DITHER_NS) {
114 av_log(s, AV_LOG_WARNING, "Requested noise shaping dither not available at this sampling rate, using triangular hp dither\n");
115 s->dither.method = SWR_DITHER_TRIANGULAR_HIGHPASS;
118 s->dither.noise = s->preout;
119 if (s->dither.method > SWR_DITHER_NS) {
120 s->dither.noise.bps = 4;
121 s->dither.noise.fmt = AV_SAMPLE_FMT_FLTP;
122 s->dither.noise_scale = 1;
128 #define TEMPLATE_DITHER_S16
129 #include "dither_template.c"
130 #undef TEMPLATE_DITHER_S16
132 #define TEMPLATE_DITHER_S32
133 #include "dither_template.c"
134 #undef TEMPLATE_DITHER_S32
136 #define TEMPLATE_DITHER_FLT
137 #include "dither_template.c"
138 #undef TEMPLATE_DITHER_FLT
140 #define TEMPLATE_DITHER_DBL
141 #include "dither_template.c"
142 #undef TEMPLATE_DITHER_DBL