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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 void 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((len + TMP_EXTRA) * sizeof(double));
30  int i;
31 
32  for(i=0; i<len + TMP_EXTRA; i++){
33  double v;
34  seed = seed* 1664525 + 1013904223;
35 
36  switch(s->dither.method){
37  case SWR_DITHER_RECTANGULAR: v= ((double)seed) / UINT_MAX - 0.5; break;
38  default:
40  v = ((double)seed) / UINT_MAX;
41  seed = seed*1664525 + 1013904223;
42  v-= ((double)seed) / UINT_MAX;
43  break;
44  }
45  tmp[i] = v;
46  }
47 
48  for(i=0; i<len; i++){
49  double v;
50 
51  switch(s->dither.method){
52  default:
54  v = tmp[i];
55  break;
57  v = (- tmp[i] + 2*tmp[i+1] - tmp[i+2]) / sqrt(6);
58  break;
59  }
60 
61  v*= scale;
62 
63  switch(noise_fmt){
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);
69  }
70  }
71 
72  av_free(tmp);
73 }
74 
75 int swri_dither_init(SwrContext *s, enum AVSampleFormat out_fmt, enum AVSampleFormat in_fmt)
76 {
77  int i;
78  double scale = 0;
79 
81  return AVERROR(EINVAL);
82 
83  out_fmt = av_get_packed_sample_fmt(out_fmt);
84  in_fmt = av_get_packed_sample_fmt( in_fmt);
85 
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);
90  }
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;
94 
95  scale *= s->dither.scale;
96 
97  if (out_fmt == AV_SAMPLE_FMT_S32 && s->dither.output_sample_bits)
98  scale *= 1<<(32-s->dither.output_sample_bits);
99 
100  s->dither.ns_pos = 0;
102  s->dither.ns_scale = scale;
103  s->dither.ns_scale_1 = scale ? 1/scale : 0;
104  memset(s->dither.ns_errors, 0, sizeof(s->dither.ns_errors));
105  for (i=0; filters[i].coefs; i++) {
106  const filter_t *f = &filters[i];
107  if (fabs(s->out_sample_rate - f->rate) / f->rate <= .05 && f->name == s->dither.method) {
108  int j;
109  s->dither.ns_taps = f->len;
110  for (j=0; j<f->len; j++)
111  s->dither.ns_coeffs[j] = f->coefs[j];
112  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  break;
114  }
115  }
116  if (!filters[i].coefs && s->dither.method > SWR_DITHER_NS) {
117  av_log(s, AV_LOG_WARNING, "Requested noise shaping dither not available at this sampling rate, using triangular hp dither\n");
119  }
120 
121  av_assert0(!s->preout.count);
122  s->dither.noise = s->preout;
123  s->dither.temp = s->preout;
124  if (s->dither.method > SWR_DITHER_NS) {
125  s->dither.noise.bps = 4;
127  s->dither.noise_scale = 1;
128  }
129 
130  return 0;
131 }
132 
133 #define TEMPLATE_DITHER_S16
134 #include "dither_template.c"
135 #undef TEMPLATE_DITHER_S16
136 
137 #define TEMPLATE_DITHER_S32
138 #include "dither_template.c"
139 #undef TEMPLATE_DITHER_S32
140 
141 #define TEMPLATE_DITHER_FLT
142 #include "dither_template.c"
143 #undef TEMPLATE_DITHER_FLT
144 
145 #define TEMPLATE_DITHER_DBL
146 #include "dither_template.c"
147 #undef TEMPLATE_DITHER_DBL