resample2.c
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1 /*
2  * audio resampling
3  * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
4  *
5  * This file is part of Libav.
6  *
7  * Libav is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * Libav is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
28 #include "avcodec.h"
29 #include "dsputil.h"
30 
31 #ifndef CONFIG_RESAMPLE_HP
32 #define FILTER_SHIFT 15
33 
34 #define FELEM int16_t
35 #define FELEM2 int32_t
36 #define FELEML int64_t
37 #define FELEM_MAX INT16_MAX
38 #define FELEM_MIN INT16_MIN
39 #define WINDOW_TYPE 9
40 #elif !defined(CONFIG_RESAMPLE_AUDIOPHILE_KIDDY_MODE)
41 #define FILTER_SHIFT 30
42 
43 #define FELEM int32_t
44 #define FELEM2 int64_t
45 #define FELEML int64_t
46 #define FELEM_MAX INT32_MAX
47 #define FELEM_MIN INT32_MIN
48 #define WINDOW_TYPE 12
49 #else
50 #define FILTER_SHIFT 0
51 
52 #define FELEM double
53 #define FELEM2 double
54 #define FELEML double
55 #define WINDOW_TYPE 24
56 #endif
57 
58 
59 typedef struct AVResampleContext{
60  const AVClass *av_class;
64  int dst_incr;
65  int index;
66  int frac;
67  int src_incr;
71  int linear;
73 
77 static double bessel(double x){
78  double v=1;
79  double lastv=0;
80  double t=1;
81  int i;
82 
83  x= x*x/4;
84  for(i=1; v != lastv; i++){
85  lastv=v;
86  t *= x/(i*i);
87  v += t;
88  }
89  return v;
90 }
91 
99 static int build_filter(FELEM *filter, double factor, int tap_count, int phase_count, int scale, int type){
100  int ph, i;
101  double x, y, w;
102  double *tab = av_malloc(tap_count * sizeof(*tab));
103  const int center= (tap_count-1)/2;
104 
105  if (!tab)
106  return AVERROR(ENOMEM);
107 
108  /* if upsampling, only need to interpolate, no filter */
109  if (factor > 1.0)
110  factor = 1.0;
111 
112  for(ph=0;ph<phase_count;ph++) {
113  double norm = 0;
114  for(i=0;i<tap_count;i++) {
115  x = M_PI * ((double)(i - center) - (double)ph / phase_count) * factor;
116  if (x == 0) y = 1.0;
117  else y = sin(x) / x;
118  switch(type){
119  case 0:{
120  const float d= -0.5; //first order derivative = -0.5
121  x = fabs(((double)(i - center) - (double)ph / phase_count) * factor);
122  if(x<1.0) y= 1 - 3*x*x + 2*x*x*x + d*( -x*x + x*x*x);
123  else y= d*(-4 + 8*x - 5*x*x + x*x*x);
124  break;}
125  case 1:
126  w = 2.0*x / (factor*tap_count) + M_PI;
127  y *= 0.3635819 - 0.4891775 * cos(w) + 0.1365995 * cos(2*w) - 0.0106411 * cos(3*w);
128  break;
129  default:
130  w = 2.0*x / (factor*tap_count*M_PI);
131  y *= bessel(type*sqrt(FFMAX(1-w*w, 0)));
132  break;
133  }
134 
135  tab[i] = y;
136  norm += y;
137  }
138 
139  /* normalize so that an uniform color remains the same */
140  for(i=0;i<tap_count;i++) {
141 #ifdef CONFIG_RESAMPLE_AUDIOPHILE_KIDDY_MODE
142  filter[ph * tap_count + i] = tab[i] / norm;
143 #else
144  filter[ph * tap_count + i] = av_clip(lrintf(tab[i] * scale / norm), FELEM_MIN, FELEM_MAX);
145 #endif
146  }
147  }
148 #if 0
149  {
150 #define LEN 1024
151  int j,k;
152  double sine[LEN + tap_count];
153  double filtered[LEN];
154  double maxff=-2, minff=2, maxsf=-2, minsf=2;
155  for(i=0; i<LEN; i++){
156  double ss=0, sf=0, ff=0;
157  for(j=0; j<LEN+tap_count; j++)
158  sine[j]= cos(i*j*M_PI/LEN);
159  for(j=0; j<LEN; j++){
160  double sum=0;
161  ph=0;
162  for(k=0; k<tap_count; k++)
163  sum += filter[ph * tap_count + k] * sine[k+j];
164  filtered[j]= sum / (1<<FILTER_SHIFT);
165  ss+= sine[j + center] * sine[j + center];
166  ff+= filtered[j] * filtered[j];
167  sf+= sine[j + center] * filtered[j];
168  }
169  ss= sqrt(2*ss/LEN);
170  ff= sqrt(2*ff/LEN);
171  sf= 2*sf/LEN;
172  maxff= FFMAX(maxff, ff);
173  minff= FFMIN(minff, ff);
174  maxsf= FFMAX(maxsf, sf);
175  minsf= FFMIN(minsf, sf);
176  if(i%11==0){
177  av_log(NULL, AV_LOG_ERROR, "i:%4d ss:%f ff:%13.6e-%13.6e sf:%13.6e-%13.6e\n", i, ss, maxff, minff, maxsf, minsf);
178  minff=minsf= 2;
179  maxff=maxsf= -2;
180  }
181  }
182  }
183 #endif
184 
185  av_free(tab);
186  return 0;
187 }
188 
189 AVResampleContext *av_resample_init(int out_rate, int in_rate, int filter_size, int phase_shift, int linear, double cutoff){
191  double factor= FFMIN(out_rate * cutoff / in_rate, 1.0);
192  int phase_count= 1<<phase_shift;
193 
194  if (!c)
195  return NULL;
196 
197  c->phase_shift= phase_shift;
198  c->phase_mask= phase_count-1;
199  c->linear= linear;
200 
201  c->filter_length= FFMAX((int)ceil(filter_size/factor), 1);
202  c->filter_bank= av_mallocz(c->filter_length*(phase_count+1)*sizeof(FELEM));
203  if (!c->filter_bank)
204  goto error;
205  if (build_filter(c->filter_bank, factor, c->filter_length, phase_count, 1<<FILTER_SHIFT, WINDOW_TYPE))
206  goto error;
207  memcpy(&c->filter_bank[c->filter_length*phase_count+1], c->filter_bank, (c->filter_length-1)*sizeof(FELEM));
208  c->filter_bank[c->filter_length*phase_count]= c->filter_bank[c->filter_length - 1];
209 
210  c->src_incr= out_rate;
211  c->ideal_dst_incr= c->dst_incr= in_rate * phase_count;
212  c->index= -phase_count*((c->filter_length-1)/2);
213 
214  return c;
215 error:
216  av_free(c->filter_bank);
217  av_free(c);
218  return NULL;
219 }
220 
222  av_freep(&c->filter_bank);
223  av_freep(&c);
224 }
225 
226 void av_resample_compensate(AVResampleContext *c, int sample_delta, int compensation_distance){
227 // sample_delta += (c->ideal_dst_incr - c->dst_incr)*(int64_t)c->compensation_distance / c->ideal_dst_incr;
228  c->compensation_distance= compensation_distance;
229  c->dst_incr = c->ideal_dst_incr - c->ideal_dst_incr * (int64_t)sample_delta / compensation_distance;
230 }
231 
232 int av_resample(AVResampleContext *c, short *dst, short *src, int *consumed, int src_size, int dst_size, int update_ctx){
233  int dst_index, i;
234  int index= c->index;
235  int frac= c->frac;
236  int dst_incr_frac= c->dst_incr % c->src_incr;
237  int dst_incr= c->dst_incr / c->src_incr;
238  int compensation_distance= c->compensation_distance;
239 
240  if(compensation_distance == 0 && c->filter_length == 1 && c->phase_shift==0){
241  int64_t index2= ((int64_t)index)<<32;
242  int64_t incr= (1LL<<32) * c->dst_incr / c->src_incr;
243  dst_size= FFMIN(dst_size, (src_size-1-index) * (int64_t)c->src_incr / c->dst_incr);
244 
245  for(dst_index=0; dst_index < dst_size; dst_index++){
246  dst[dst_index] = src[index2>>32];
247  index2 += incr;
248  }
249  frac += dst_index * dst_incr_frac;
250  index += dst_index * dst_incr;
251  index += frac / c->src_incr;
252  frac %= c->src_incr;
253  }else{
254  for(dst_index=0; dst_index < dst_size; dst_index++){
255  FELEM *filter= c->filter_bank + c->filter_length*(index & c->phase_mask);
256  int sample_index= index >> c->phase_shift;
257  FELEM2 val=0;
258 
259  if(sample_index < 0){
260  for(i=0; i<c->filter_length; i++)
261  val += src[FFABS(sample_index + i) % src_size] * filter[i];
262  }else if(sample_index + c->filter_length > src_size){
263  break;
264  }else if(c->linear){
265  FELEM2 v2=0;
266  for(i=0; i<c->filter_length; i++){
267  val += src[sample_index + i] * (FELEM2)filter[i];
268  v2 += src[sample_index + i] * (FELEM2)filter[i + c->filter_length];
269  }
270  val+=(v2-val)*(FELEML)frac / c->src_incr;
271  }else{
272  for(i=0; i<c->filter_length; i++){
273  val += src[sample_index + i] * (FELEM2)filter[i];
274  }
275  }
276 
277 #ifdef CONFIG_RESAMPLE_AUDIOPHILE_KIDDY_MODE
278  dst[dst_index] = av_clip_int16(lrintf(val));
279 #else
280  val = (val + (1<<(FILTER_SHIFT-1)))>>FILTER_SHIFT;
281  dst[dst_index] = (unsigned)(val + 32768) > 65535 ? (val>>31) ^ 32767 : val;
282 #endif
283 
284  frac += dst_incr_frac;
285  index += dst_incr;
286  if(frac >= c->src_incr){
287  frac -= c->src_incr;
288  index++;
289  }
290 
291  if(dst_index + 1 == compensation_distance){
292  compensation_distance= 0;
293  dst_incr_frac= c->ideal_dst_incr % c->src_incr;
294  dst_incr= c->ideal_dst_incr / c->src_incr;
295  }
296  }
297  }
298  *consumed= FFMAX(index, 0) >> c->phase_shift;
299  if(index>=0) index &= c->phase_mask;
300 
301  if(compensation_distance){
302  compensation_distance -= dst_index;
303  assert(compensation_distance > 0);
304  }
305  if(update_ctx){
306  c->frac= frac;
307  c->index= index;
308  c->dst_incr= dst_incr_frac + c->src_incr*dst_incr;
309  c->compensation_distance= compensation_distance;
310  }
311 #if 0
312  if(update_ctx && !c->compensation_distance){
313 #undef rand
314  av_resample_compensate(c, rand() % (8000*2) - 8000, 8000*2);
316  }
317 #endif
318 
319  return dst_index;
320 }