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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  if (scale == 0) {
106  s->dither.method = 0;
107  return 0;
108  }
109 
110  s->dither.ns_pos = 0;
111  s->dither.noise_scale= scale;
112  s->dither.ns_scale = scale;
113  s->dither.ns_scale_1 = scale ? 1/scale : 0;
114  memset(s->dither.ns_errors, 0, sizeof(s->dither.ns_errors));
115  for (i=0; filters[i].coefs; i++) {
116  const filter_t *f = &filters[i];
117  if (llabs(s->out_sample_rate - f->rate)*20 <= f->rate && f->name == s->dither.method) {
118  int j;
119  s->dither.ns_taps = f->len;
120  for (j=0; j<f->len; j++)
121  s->dither.ns_coeffs[j] = f->coefs[j];
122  s->dither.ns_scale_1 *= 1 - exp(f->gain_cB * M_LN10 * 0.005) * 2 / (1<<(8*av_get_bytes_per_sample(out_fmt)));
123  break;
124  }
125  }
126  if (!filters[i].coefs && s->dither.method > SWR_DITHER_NS) {
127  av_log(s, AV_LOG_WARNING, "Requested noise shaping dither not available at this sampling rate, using triangular hp dither\n");
129  }
130 
131  return 0;
132 }
133 
134 #define TEMPLATE_DITHER_S16
135 #include "dither_template.c"
136 #undef TEMPLATE_DITHER_S16
137 
138 #define TEMPLATE_DITHER_S32
139 #include "dither_template.c"
140 #undef TEMPLATE_DITHER_S32
141 
142 #define TEMPLATE_DITHER_FLT
143 #include "dither_template.c"
144 #undef TEMPLATE_DITHER_FLT
145 
146 #define TEMPLATE_DITHER_DBL
147 #include "dither_template.c"
148 #undef TEMPLATE_DITHER_DBL
float, planar
Definition: samplefmt.h:69
const char * s
Definition: avisynth_c.h:768
int out_sample_rate
output sample rate
enum AVResampleDitherMethod method
Definition: dither.c:56
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:182
double, planar
Definition: samplefmt.h:70
float ns_scale
Noise shaping dither scale.
float ns_coeffs[NS_TAPS]
Noise shaping filter coefficients.
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition: avassert.h:37
#define TMP_EXTRA
float ns_errors[SWR_CH_MAX][2 *NS_TAPS]
#define av_cold
Definition: attributes.h:82
AV_SAMPLE_FMT_U8
int swri_get_dither(SwrContext *s, void *dst, int len, unsigned seed, enum AVSampleFormat noise_fmt)
Definition: dither.c:26
signed 32 bits
Definition: samplefmt.h:62
#define av_log(a,...)
enum SwrDitherType name
int output_sample_bits
the number of used output bits, needed to scale dither correctly
av_cold int swri_dither_init(SwrContext *s, enum AVSampleFormat out_fmt, enum AVSampleFormat in_fmt)
Definition: dither.c:79
#define AVERROR(e)
Definition: error.h:43
The libswresample context.
simple assert() macros that are a bit more flexible than ISO C assert().
int8_t exp
Definition: eval.c:64
not part of API/ABI
Definition: swresample.h:158
signed 32 bits, planar
Definition: samplefmt.h:68
int32_t
not part of API/ABI
Definition: swresample.h:150
float ns_scale_1
Noise shaping dither scale^-1.
float noise_scale
Noise scale.
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:58
double const * coefs
static unsigned int seed
Definition: videogen.c:78
int ns_pos
Noise shaping dither position.
struct DitherContext dither
int av_get_bytes_per_sample(enum AVSampleFormat sample_fmt)
Return number of bytes per sample.
Definition: samplefmt.c:106
#define M_LN10
Definition: mathematics.h:43
enum AVSampleFormat av_get_packed_sample_fmt(enum AVSampleFormat sample_fmt)
Get the packed alternative form of the given sample format.
Definition: samplefmt.c:75
signed 16 bits
Definition: samplefmt.h:61
#define av_free(p)
int len
static uint8_t tmp[8]
Definition: des.c:38
static const struct PPFilter filters[]
Definition: postprocess.c:137
signed 16 bits, planar
Definition: samplefmt.h:67
#define av_malloc_array(a, b)
int ns_taps
Noise shaping dither taps.