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dither.c
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1 /*
2  * Copyright (C) 2012-2013 Michael Niedermayer (michaelni@gmx.at)
3  *
4  * This file is part of libswresample
5  *
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.
10  *
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.
15  *
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
19  */
20 
21 #include "libavutil/avassert.h"
22 #include "swresample_internal.h"
23 
24 #include "noise_shaping_data.c"
25 
26 int swri_get_dither(SwrContext *s, void *dst, int len, unsigned seed, enum AVSampleFormat noise_fmt) {
27  double scale = s->dither.noise_scale;
28 #define TMP_EXTRA 2
29  double *tmp = av_malloc_array(len + TMP_EXTRA, sizeof(double));
30  int i;
31 
32  if (!tmp)
33  return AVERROR(ENOMEM);
34 
35  for(i=0; i<len + TMP_EXTRA; i++){
36  double v;
37  seed = seed* 1664525 + 1013904223;
38 
39  switch(s->dither.method){
40  case SWR_DITHER_RECTANGULAR: v= ((double)seed) / UINT_MAX - 0.5; break;
41  default:
43  v = ((double)seed) / UINT_MAX;
44  seed = seed*1664525 + 1013904223;
45  v-= ((double)seed) / UINT_MAX;
46  break;
47  }
48  tmp[i] = v;
49  }
50 
51  for(i=0; i<len; i++){
52  double v;
53 
54  switch(s->dither.method){
55  default:
57  v = tmp[i];
58  break;
60  v = (- tmp[i] + 2*tmp[i+1] - tmp[i+2]) / sqrt(6);
61  break;
62  }
63 
64  v*= scale;
65 
66  switch(noise_fmt){
67  case AV_SAMPLE_FMT_S16P: ((int16_t*)dst)[i] = v; break;
68  case AV_SAMPLE_FMT_S32P: ((int32_t*)dst)[i] = v; break;
69  case AV_SAMPLE_FMT_FLTP: ((float *)dst)[i] = v; break;
70  case AV_SAMPLE_FMT_DBLP: ((double *)dst)[i] = v; break;
71  default: av_assert0(0);
72  }
73  }
74 
75  av_free(tmp);
76  return 0;
77 }
78 
80 {
81  int i;
82  double scale = 0;
83 
85  return AVERROR(EINVAL);
86 
87  out_fmt = av_get_packed_sample_fmt(out_fmt);
88  in_fmt = av_get_packed_sample_fmt( in_fmt);
89 
90  if(in_fmt == AV_SAMPLE_FMT_FLT || in_fmt == AV_SAMPLE_FMT_DBL){
91  if(out_fmt == AV_SAMPLE_FMT_S32) scale = 1.0/(1LL<<31);
92  if(out_fmt == AV_SAMPLE_FMT_S16) scale = 1.0/(1LL<<15);
93  if(out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1.0/(1LL<< 7);
94  }
95  if(in_fmt == AV_SAMPLE_FMT_S32 && out_fmt == AV_SAMPLE_FMT_S32 && (s->dither.output_sample_bits&31)) scale = 1;
96  if(in_fmt == AV_SAMPLE_FMT_S32 && out_fmt == AV_SAMPLE_FMT_S16) scale = 1<<16;
97  if(in_fmt == AV_SAMPLE_FMT_S32 && out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1<<24;
98  if(in_fmt == AV_SAMPLE_FMT_S16 && out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1<<8;
99 
100  scale *= s->dither.scale;
101 
102  if (out_fmt == AV_SAMPLE_FMT_S32 && s->dither.output_sample_bits)
103  scale *= 1<<(32-s->dither.output_sample_bits);
104 
105  s->dither.ns_pos = 0;
106  s->dither.noise_scale= scale;
107  s->dither.ns_scale = scale;
108  s->dither.ns_scale_1 = scale ? 1/scale : 0;
109  memset(s->dither.ns_errors, 0, sizeof(s->dither.ns_errors));
110  for (i=0; filters[i].coefs; i++) {
111  const filter_t *f = &filters[i];
112  if (fabs(s->out_sample_rate - f->rate) / f->rate <= .05 && f->name == s->dither.method) {
113  int j;
114  s->dither.ns_taps = f->len;
115  for (j=0; j<f->len; j++)
116  s->dither.ns_coeffs[j] = f->coefs[j];
117  s->dither.ns_scale_1 *= 1 - exp(f->gain_cB * M_LN10 * 0.005) * 2 / (1<<(8*av_get_bytes_per_sample(out_fmt)));
118  break;
119  }
120  }
121  if (!filters[i].coefs && s->dither.method > SWR_DITHER_NS) {
122  av_log(s, AV_LOG_WARNING, "Requested noise shaping dither not available at this sampling rate, using triangular hp dither\n");
124  }
125 
126  av_assert0(!s->preout.count);
127  s->dither.noise = s->preout;
128  s->dither.temp = s->preout;
129  if (s->dither.method > SWR_DITHER_NS) {
130  s->dither.noise.bps = 4;
132  s->dither.noise_scale = 1;
133  }
134 
135  return 0;
136 }
137 
138 #define TEMPLATE_DITHER_S16
139 #include "dither_template.c"
140 #undef TEMPLATE_DITHER_S16
141 
142 #define TEMPLATE_DITHER_S32
143 #include "dither_template.c"
144 #undef TEMPLATE_DITHER_S32
145 
146 #define TEMPLATE_DITHER_FLT
147 #include "dither_template.c"
148 #undef TEMPLATE_DITHER_FLT
149 
150 #define TEMPLATE_DITHER_DBL
151 #include "dither_template.c"
152 #undef TEMPLATE_DITHER_DBL