FFmpeg
 All Data Structures Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
dither_template.c
Go to the documentation of this file.
1 
2 #if defined(TEMPLATE_DITHER_DBL)
3 # define RENAME(N) N ## _double
4 # define DELEM double
5 # define CLIP(v)
6 
7 #elif defined(TEMPLATE_DITHER_FLT)
8 # define RENAME(N) N ## _float
9 # define DELEM float
10 # define CLIP(v)
11 
12 #elif defined(TEMPLATE_DITHER_S32)
13 # define RENAME(N) N ## _int32
14 # define DELEM int32_t
15 # define CLIP(v) v = FFMAX(FFMIN(v, INT32_MAX), INT32_MIN)
16 
17 #elif defined(TEMPLATE_DITHER_S16)
18 # define RENAME(N) N ## _int16
19 # define DELEM int16_t
20 # define CLIP(v) v = FFMAX(FFMIN(v, INT16_MAX), INT16_MIN)
21 
22 #else
23 ERROR
24 #endif
25 
26 void RENAME(swri_noise_shaping)(SwrContext *s, AudioData *dsts, const AudioData *srcs, const AudioData *noises, int count){
27  int pos = s->dither.ns_pos;
28  int i, j, ch;
29  int taps = s->dither.ns_taps;
30  float S = s->dither.ns_scale;
31  float S_1 = s->dither.ns_scale_1;
32 
33  av_assert2((taps&3) != 2);
34  av_assert2((taps&3) != 3 || s->dither.ns_coeffs[taps] == 0);
35 
36  for (ch=0; ch<srcs->ch_count; ch++) {
37  const float *noise = ((const float *)noises->ch[ch]) + s->dither.noise_pos;
38  const DELEM *src = (const DELEM*)srcs->ch[ch];
39  DELEM *dst = (DELEM*)dsts->ch[ch];
40  float *ns_errors = s->dither.ns_errors[ch];
41  const float *ns_coeffs = s->dither.ns_coeffs;
42  pos = s->dither.ns_pos;
43  for (i=0; i<count; i++) {
44  double d1, d = src[i]*S_1;
45  for(j=0; j<taps-2; j+=4) {
46  d -= ns_coeffs[j ] * ns_errors[pos + j ]
47  +ns_coeffs[j + 1] * ns_errors[pos + j + 1]
48  +ns_coeffs[j + 2] * ns_errors[pos + j + 2]
49  +ns_coeffs[j + 3] * ns_errors[pos + j + 3];
50  }
51  if(j < taps)
52  d -= ns_coeffs[j] * ns_errors[pos + j];
53  pos = pos ? pos - 1 : taps - 1;
54  d1 = rint(d + noise[i]);
55  ns_errors[pos + taps] = ns_errors[pos] = d1 - d;
56  d1 *= S;
57  CLIP(d1);
58  dst[i] = d1;
59  }
60  }
61 
62  s->dither.ns_pos = pos;
63 }
64 
65 #undef RENAME
66 #undef DELEM
67 #undef CLIP