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af_replaygain.c
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1 /*
2  * Copyright (c) 1998 - 2009 Conifer Software
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg 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  * FFmpeg 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 FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 /**
22  * @file
23  * ReplayGain scanner
24  */
25 
26 #include "libavutil/avassert.h"
28 #include "audio.h"
29 #include "avfilter.h"
30 #include "internal.h"
31 
32 #define HISTOGRAM_SLOTS 12000
33 #define BUTTER_ORDER 2
34 #define YULE_ORDER 10
35 
36 typedef struct ReplayGainFreqInfo {
38  double BYule[YULE_ORDER + 1];
39  double AYule[YULE_ORDER + 1];
40  double BButter[BUTTER_ORDER + 1];
41  double AButter[BUTTER_ORDER + 1];
43 
44 static const ReplayGainFreqInfo freqinfos[] =
45 {
46  {
47  192000,
48  { 0.01184742123123, -0.04631092400086, 0.06584226961238,
49  -0.02165588522478, -0.05656260778952, 0.08607493592760,
50  -0.03375544339786, -0.04216579932754, 0.06416711490648,
51  -0.03444708260844, 0.00697275872241 },
52  { 1.00000000000000, -5.24727318348167, 10.60821585192244,
53  -8.74127665810413, -1.33906071371683, 8.07972882096606,
54  -5.46179918950847, 0.54318070652536, 0.87450969224280,
55  -0.34656083539754, 0.03034796843589 },
56  { 0.99653501465135, -1.99307002930271, 0.99653501465135 },
57  { 1.00000000000000, -1.99305802314321, 0.99308203546221 },
58  },
59  {
60  176400,
61  { 0.00268568524529, -0.00852379426080, 0.00852704191347,
62  0.00146116310295, -0.00950855828762, 0.00625449515499,
63  0.00116183868722, -0.00362461417136, 0.00203961000134,
64  -0.00050664587933, 0.00004327455427 },
65  { 1.00000000000000, -5.57512782763045, 12.44291056065794,
66  -12.87462799681221, 3.08554846961576, 6.62493459880692,
67  -7.07662766313248, 2.51175542736441, 0.06731510802735,
68  -0.24567753819213, 0.03961404162376 },
69  { 0.99622916581118, -1.99245833162236, 0.99622916581118 },
70  { 1.00000000000000, -1.99244411238133, 0.99247255086339 },
71  },
72  {
73  144000,
74  { 0.00639682359450, -0.02556437970955, 0.04230854400938,
75  -0.03722462201267, 0.01718514827295, 0.00610592243009,
76  -0.03065965747365, 0.04345745003539, -0.03298592681309,
77  0.01320937236809, -0.00220304127757 },
78  { 1.00000000000000, -6.14814623523425, 15.80002457141566,
79  -20.78487587686937, 11.98848552310315, 3.36462015062606,
80  -10.22419868359470, 6.65599702146473, -1.67141861110485,
81  -0.05417956536718, 0.07374767867406 },
82  { 0.99538268958706, -1.99076537917413, 0.99538268958706 },
83  { 1.00000000000000, -1.99074405950505, 0.99078669884321 },
84  },
85  {
86  128000,
87  { 0.00553120584305, -0.02112620545016, 0.03549076243117,
88  -0.03362498312306, 0.01425867248183, 0.01344686928787,
89  -0.03392770787836, 0.03464136459530, -0.02039116051549,
90  0.00667420794705, -0.00093763762995 },
91  { 1.00000000000000, -6.14581710839925, 16.04785903675838,
92  -22.19089131407749, 15.24756471580286, -0.52001440400238,
93  -8.00488641699940, 6.60916094768855, -2.37856022810923,
94  0.33106947986101, 0.00459820832036 },
95  { 0.99480702681278, -1.98961405362557, 0.99480702681278 },
96  { 1.00000000000000, -1.98958708647324, 0.98964102077790 },
97  },
98  {
99  112000,
100  { 0.00528778718259, -0.01893240907245, 0.03185982561867,
101  -0.02926260297838, 0.00715743034072, 0.01985743355827,
102  -0.03222614850941, 0.02565681978192, -0.01210662313473,
103  0.00325436284541, -0.00044173593001 },
104  { 1.00000000000000, -6.24932108456288, 17.42344320538476,
105  -27.86819709054896, 26.79087344681326,-13.43711081485123,
106  -0.66023612948173, 6.03658091814935, -4.24926577030310,
107  1.40829268709186, -0.19480852628112 },
108  { 0.99406737810867, -1.98813475621734, 0.99406737810867 },
109  { 1.00000000000000, -1.98809955990514, 0.98816995252954 },
110  },
111  {
112  96000,
113  { 0.00588138296683, -0.01613559730421, 0.02184798954216,
114  -0.01742490405317, 0.00464635643780, 0.01117772513205,
115  -0.02123865824368, 0.01959354413350, -0.01079720643523,
116  0.00352183686289, -0.00063124341421 },
117  { 1.00000000000000, -5.97808823642008, 16.21362507964068,
118  -25.72923730652599, 25.40470663139513,-14.66166287771134,
119  2.81597484359752, 2.51447125969733, -2.23575306985286,
120  0.75788151036791, -0.10078025199029 },
121  { 0.99308203517541, -1.98616407035082, 0.99308203517541 },
122  { 1.00000000000000, -1.98611621154089, 0.98621192916075 },
123  },
124  {
125  88200,
126  { 0.02667482047416, -0.11377479336097, 0.23063167910965,
127  -0.30726477945593, 0.33188520686529, -0.33862680249063,
128  0.31807161531340, -0.23730796929880, 0.12273894790371,
129  -0.03840017967282, 0.00549673387936 },
130  { 1.00000000000000, -6.31836451657302, 18.31351310801799,
131  -31.88210014815921, 36.53792146976740,-28.23393036467559,
132  14.24725258227189, -4.04670980012854, 0.18865757280515,
133  0.25420333563908, -0.06012333531065 },
134  { 0.99247255046129, -1.98494510092259, 0.99247255046129 },
135  { 1.00000000000000, -1.98488843762335, 0.98500176422183 },
136  },
137  {
138  64000,
139  { 0.02613056568174, -0.08128786488109, 0.14937282347325,
140  -0.21695711675126, 0.25010286673402, -0.23162283619278,
141  0.17424041833052, -0.10299599216680, 0.04258696481981,
142  -0.00977952936493, 0.00105325558889 },
143  { 1.00000000000000, -5.73625477092119, 16.15249794355035,
144  -29.68654912464508, 39.55706155674083,-39.82524556246253,
145  30.50605345013009,-17.43051772821245, 7.05154573908017,
146  -1.80783839720514, 0.22127840210813 },
147  { 0.98964101933472, -1.97928203866944, 0.98964101933472 },
148  { 1.00000000000000, -1.97917472731009, 0.97938935002880 },
149  },
150  {
151  56000,
152  { 0.03144914734085, -0.06151729206963, 0.08066788708145,
153  -0.09737939921516, 0.08943210803999, -0.06989984672010,
154  0.04926972841044, -0.03161257848451, 0.01456837493506,
155  -0.00316015108496, 0.00132807215875 },
156  { 1.00000000000000, -4.87377313090032, 12.03922160140209,
157  -20.10151118381395, 25.10388534415171,-24.29065560815903,
158  18.27158469090663,-10.45249552560593, 4.30319491872003,
159  -1.13716992070185, 0.14510733527035 },
160  { 0.98816995007392, -1.97633990014784, 0.98816995007392 },
161  { 1.00000000000000, -1.97619994516973, 0.97647985512594 },
162  },
163  {
164  48000,
165  { 0.03857599435200, -0.02160367184185, -0.00123395316851,
166  -0.00009291677959, -0.01655260341619, 0.02161526843274,
167  -0.02074045215285, 0.00594298065125, 0.00306428023191,
168  0.00012025322027, 0.00288463683916 },
169  { 1.00000000000000, -3.84664617118067, 7.81501653005538,
170  -11.34170355132042, 13.05504219327545,-12.28759895145294,
171  9.48293806319790, -5.87257861775999, 2.75465861874613,
172  -0.86984376593551, 0.13919314567432 },
173  { 0.98621192462708, -1.97242384925416, 0.98621192462708 },
174  { 1.00000000000000, -1.97223372919527, 0.97261396931306 },
175  },
176  {
177  44100,
178  { 0.05418656406430, -0.02911007808948, -0.00848709379851,
179  -0.00851165645469, -0.00834990904936, 0.02245293253339,
180  -0.02596338512915, 0.01624864962975, -0.00240879051584,
181  0.00674613682247, -0.00187763777362 },
182  { 1.00000000000000, -3.47845948550071, 6.36317777566148,
183  -8.54751527471874, 9.47693607801280, -8.81498681370155,
184  6.85401540936998, -4.39470996079559, 2.19611684890774,
185  -0.75104302451432, 0.13149317958808 },
186  { 0.98500175787242, -1.97000351574484, 0.98500175787242 },
187  { 1.00000000000000, -1.96977855582618, 0.97022847566350 },
188  },
189  {
190  37800,
191  { 0.08717879977844, -0.01000374016172, -0.06265852122368,
192  -0.01119328800950, -0.00114279372960, 0.02081333954769,
193  -0.01603261863207, 0.01936763028546, 0.00760044736442,
194  -0.00303979112271, -0.00075088605788 },
195  { 1.00000000000000, -2.62816311472146, 3.53734535817992,
196  -3.81003448678921, 3.91291636730132, -3.53518605896288,
197  2.71356866157873, -1.86723311846592, 1.12075382367659,
198  -0.48574086886890, 0.11330544663849 },
199  { 0.98252400815195, -1.96504801630391, 0.98252400815195 },
200  { 1.00000000000000, -1.96474258269041, 0.96535344991740 },
201  },
202  {
203  32000,
204  { 0.15457299681924, -0.09331049056315, -0.06247880153653,
205  0.02163541888798, -0.05588393329856, 0.04781476674921,
206  0.00222312597743, 0.03174092540049, -0.01390589421898,
207  0.00651420667831, -0.00881362733839 },
208  { 1.00000000000000, -2.37898834973084, 2.84868151156327,
209  -2.64577170229825, 2.23697657451713, -1.67148153367602,
210  1.00595954808547, -0.45953458054983, 0.16378164858596,
211  -0.05032077717131, 0.02347897407020 },
212  { 0.97938932735214, -1.95877865470428, 0.97938932735214 },
213  { 1.00000000000000, -1.95835380975398, 0.95920349965459 },
214  },
215  {
216  24000,
217  { 0.30296907319327, -0.22613988682123, -0.08587323730772,
218  0.03282930172664, -0.00915702933434, -0.02364141202522,
219  -0.00584456039913, 0.06276101321749, -0.00000828086748,
220  0.00205861885564, -0.02950134983287 },
221  { 1.00000000000000, -1.61273165137247, 1.07977492259970,
222  -0.25656257754070, -0.16276719120440, -0.22638893773906,
223  0.39120800788284, -0.22138138954925, 0.04500235387352,
224  0.02005851806501, 0.00302439095741 },
225  { 0.97531843204928, -1.95063686409857, 0.97531843204928 },
226  { 1.00000000000000, -1.95002759149878, 0.95124613669835 },
227  },
228  {
229  22050,
230  { 0.33642304856132, -0.25572241425570, -0.11828570177555,
231  0.11921148675203, -0.07834489609479, -0.00469977914380,
232  -0.00589500224440, 0.05724228140351, 0.00832043980773,
233  -0.01635381384540, -0.01760176568150 },
234  { 1.00000000000000, -1.49858979367799, 0.87350271418188,
235  0.12205022308084, -0.80774944671438, 0.47854794562326,
236  -0.12453458140019, -0.04067510197014, 0.08333755284107,
237  -0.04237348025746, 0.02977207319925 },
238  { 0.97316523498161, -1.94633046996323, 0.97316523498161 },
239  { 1.00000000000000, -1.94561023566527, 0.94705070426118 },
240  },
241  {
242  18900,
243  { 0.38524531015142, -0.27682212062067, -0.09980181488805,
244  0.09951486755646, -0.08934020156622, -0.00322369330199,
245  -0.00110329090689, 0.03784509844682, 0.01683906213303,
246  -0.01147039862572, -0.01941767987192 },
247  { 1.00000000000000, -1.29708918404534, 0.90399339674203,
248  -0.29613799017877, -0.42326645916207, 0.37934887402200,
249  -0.37919795944938, 0.23410283284785, -0.03892971758879,
250  0.00403009552351, 0.03640166626278 },
251  { 0.96535326815829, -1.93070653631658, 0.96535326815829 },
252  { 1.00000000000000, -1.92950577983524, 0.93190729279793 },
253  },
254  {
255  16000,
256  { 0.44915256608450, -0.14351757464547, -0.22784394429749,
257  -0.01419140100551, 0.04078262797139, -0.12398163381748,
258  0.04097565135648, 0.10478503600251, -0.01863887810927,
259  -0.03193428438915, 0.00541907748707 },
260  { 1.00000000000000, -0.62820619233671, 0.29661783706366,
261  -0.37256372942400, 0.00213767857124, -0.42029820170918,
262  0.22199650564824, 0.00613424350682, 0.06747620744683,
263  0.05784820375801, 0.03222754072173 },
264  { 0.96454515552826, -1.92909031105652, 0.96454515552826 },
265  { 1.00000000000000, -1.92783286977036, 0.93034775234268 },
266  },
267  {
268  12000,
269  { 0.56619470757641, -0.75464456939302, 0.16242137742230,
270  0.16744243493672, -0.18901604199609, 0.30931782841830,
271  -0.27562961986224, 0.00647310677246, 0.08647503780351,
272  -0.03788984554840, -0.00588215443421 },
273  { 1.00000000000000, -1.04800335126349, 0.29156311971249,
274  -0.26806001042947, 0.00819999645858, 0.45054734505008,
275  -0.33032403314006, 0.06739368333110, -0.04784254229033,
276  0.01639907836189, 0.01807364323573 },
277  { 0.96009142950541, -1.92018285901082, 0.96009142950541 },
278  { 1.00000000000000, -1.91858953033784, 0.92177618768381 },
279  },
280  {
281  11025,
282  { 0.58100494960553, -0.53174909058578, -0.14289799034253,
283  0.17520704835522, 0.02377945217615, 0.15558449135573,
284  -0.25344790059353, 0.01628462406333, 0.06920467763959,
285  -0.03721611395801, -0.00749618797172 },
286  { 1.00000000000000, -0.51035327095184, -0.31863563325245,
287  -0.20256413484477, 0.14728154134330, 0.38952639978999,
288  -0.23313271880868, -0.05246019024463, -0.02505961724053,
289  0.02442357316099, 0.01818801111503 },
290  { 0.95856916599601, -1.91713833199203, 0.95856916599601 },
291  { 1.00000000000000, -1.91542108074780, 0.91885558323625 },
292  },
293  {
294  8000,
295  { 0.53648789255105, -0.42163034350696, -0.00275953611929,
296  0.04267842219415, -0.10214864179676, 0.14590772289388,
297  -0.02459864859345, -0.11202315195388, -0.04060034127000,
298  0.04788665548180, -0.02217936801134 },
299  { 1.00000000000000, -0.25049871956020, -0.43193942311114,
300  -0.03424681017675, -0.04678328784242, 0.26408300200955,
301  0.15113130533216, -0.17556493366449, -0.18823009262115,
302  0.05477720428674, 0.04704409688120 },
303  { 0.94597685600279, -1.89195371200558, 0.94597685600279 },
304  { 1.00000000000000, -1.88903307939452, 0.89487434461664 },
305  },
306 };
307 
308 typedef struct ReplayGainContext {
310  float peak;
312  const double *yule_coeff_a;
313  const double *yule_coeff_b;
314  const double *butter_coeff_a;
315  const double *butter_coeff_b;
316  float yule_hist_a[256];
317  float yule_hist_b[256];
318  float butter_hist_a[256];
319  float butter_hist_b[256];
321 
323 {
324  AVFilterFormats *formats = NULL;
326  int i;
327 
328  ff_add_format(&formats, AV_SAMPLE_FMT_FLT);
329  ff_set_common_formats(ctx, formats);
331  ff_set_common_channel_layouts(ctx, layout);
332 
333  formats = NULL;
334  for (i = 0; i < FF_ARRAY_ELEMS(freqinfos); i++)
335  ff_add_format(&formats, freqinfos[i].sample_rate);
336  ff_set_common_samplerates(ctx, formats);
337 
338  return 0;
339 }
340 
341 static int config_input(AVFilterLink *inlink)
342 {
343  AVFilterContext *ctx = inlink->dst;
344  ReplayGainContext *s = ctx->priv;
345  int i;
346 
347  for (i = 0; i < FF_ARRAY_ELEMS(freqinfos); i++) {
348  if (freqinfos[i].sample_rate == inlink->sample_rate)
349  break;
350  }
351  av_assert0(i < FF_ARRAY_ELEMS(freqinfos));
352 
353  s->yule_coeff_a = freqinfos[i].AYule;
354  s->yule_coeff_b = freqinfos[i].BYule;
355  s->butter_coeff_a = freqinfos[i].AButter;
356  s->butter_coeff_b = freqinfos[i].BButter;
357 
358  s->yule_hist_i = 20;
359  s->butter_hist_i = 4;
360  inlink->partial_buf_size =
361  inlink->min_samples =
362  inlink->max_samples = inlink->sample_rate / 20;
363 
364  return 0;
365 }
366 
367 /*
368  * Update largest absolute sample value.
369  */
370 static void calc_stereo_peak(const float *samples, int nb_samples,
371  float *peak_p)
372 {
373  float peak = 0.0;
374 
375  while (nb_samples--) {
376  if (samples[0] > peak)
377  peak = samples[0];
378  else if (-samples[0] > peak)
379  peak = -samples[0];
380 
381  if (samples[1] > peak)
382  peak = samples[1];
383  else if (-samples[1] > peak)
384  peak = -samples[1];
385 
386  samples += 2;
387  }
388 
389  *peak_p = FFMAX(peak, *peak_p);
390 }
391 
392 /*
393  * Calculate stereo RMS level. Minimum value is about -100 dB for
394  * digital silence. The 90 dB offset is to compensate for the
395  * normalized float range and 3 dB is for stereo samples.
396  */
397 static double calc_stereo_rms(const float *samples, int nb_samples)
398 {
399  int count = nb_samples;
400  double sum = 1e-16;
401 
402  while (count--) {
403  sum += samples[0] * samples[0] + samples[1] * samples[1];
404  samples += 2;
405  }
406 
407  return 10 * log10 (sum / nb_samples) + 90.0 - 3.0;
408 }
409 
410 /*
411  * Optimized implementation of 2nd-order IIR stereo filter.
412  */
414  float *samples, int nb_samples)
415 {
416  const double *coeff_a = s->butter_coeff_a;
417  const double *coeff_b = s->butter_coeff_b;
418  float *hist_a = s->butter_hist_a;
419  float *hist_b = s->butter_hist_b;
420  double left, right;
421  int i, j;
422 
423  i = s->butter_hist_i;
424 
425  // If filter history is very small magnitude, clear it completely
426  // to prevent denormals from rattling around in there forever
427  // (slowing us down).
428 
429  for (j = -4; j < 0; ++j)
430  if (fabs(hist_a[i + j]) > 1e-10 || fabs(hist_b[i + j]) > 1e-10)
431  break;
432 
433  if (!j) {
434  memset(s->butter_hist_a, 0, sizeof(s->butter_hist_a));
435  memset(s->butter_hist_b, 0, sizeof(s->butter_hist_b));
436  }
437 
438  while (nb_samples--) {
439  left = (hist_b[i ] = samples[0]) * coeff_b[0];
440  right = (hist_b[i + 1] = samples[1]) * coeff_b[0];
441  left += hist_b[i - 2] * coeff_b[1] - hist_a[i - 2] * coeff_a[1];
442  right += hist_b[i - 1] * coeff_b[1] - hist_a[i - 1] * coeff_a[1];
443  left += hist_b[i - 4] * coeff_b[2] - hist_a[i - 4] * coeff_a[2];
444  right += hist_b[i - 3] * coeff_b[2] - hist_a[i - 3] * coeff_a[2];
445  samples[0] = hist_a[i ] = (float) left;
446  samples[1] = hist_a[i + 1] = (float) right;
447  samples += 2;
448 
449  if ((i += 2) == 256) {
450  memcpy(hist_a, hist_a + 252, sizeof(*hist_a) * 4);
451  memcpy(hist_b, hist_b + 252, sizeof(*hist_b) * 4);
452  i = 4;
453  }
454  }
455 
456  s->butter_hist_i = i;
457 }
458 
459 /*
460  * Optimized implementation of 10th-order IIR stereo filter.
461  */
463  float *dst, int nb_samples)
464 {
465  const double *coeff_a = s->yule_coeff_a;
466  const double *coeff_b = s->yule_coeff_b;
467  float *hist_a = s->yule_hist_a;
468  float *hist_b = s->yule_hist_b;
469  double left, right;
470  int i, j;
471 
472  i = s->yule_hist_i;
473 
474  // If filter history is very small magnitude, clear it completely to
475  // prevent denormals from rattling around in there forever
476  // (slowing us down).
477 
478  for (j = -20; j < 0; ++j)
479  if (fabs(hist_a[i + j]) > 1e-10 || fabs(hist_b[i + j]) > 1e-10)
480  break;
481 
482  if (!j) {
483  memset(s->yule_hist_a, 0, sizeof(s->yule_hist_a));
484  memset(s->yule_hist_b, 0, sizeof(s->yule_hist_b));
485  }
486 
487  while (nb_samples--) {
488  left = (hist_b[i] = src[0]) * coeff_b[0];
489  right = (hist_b[i + 1] = src[1]) * coeff_b[0];
490  left += hist_b[i - 2] * coeff_b[ 1] - hist_a[i - 2] * coeff_a[1 ];
491  right += hist_b[i - 1] * coeff_b[ 1] - hist_a[i - 1] * coeff_a[1 ];
492  left += hist_b[i - 4] * coeff_b[ 2] - hist_a[i - 4] * coeff_a[2 ];
493  right += hist_b[i - 3] * coeff_b[ 2] - hist_a[i - 3] * coeff_a[2 ];
494  left += hist_b[i - 6] * coeff_b[ 3] - hist_a[i - 6] * coeff_a[3 ];
495  right += hist_b[i - 5] * coeff_b[ 3] - hist_a[i - 5] * coeff_a[3 ];
496  left += hist_b[i - 8] * coeff_b[ 4] - hist_a[i - 8] * coeff_a[4 ];
497  right += hist_b[i - 7] * coeff_b[ 4] - hist_a[i - 7] * coeff_a[4 ];
498  left += hist_b[i - 10] * coeff_b[ 5] - hist_a[i - 10] * coeff_a[5 ];
499  right += hist_b[i - 9] * coeff_b[ 5] - hist_a[i - 9] * coeff_a[5 ];
500  left += hist_b[i - 12] * coeff_b[ 6] - hist_a[i - 12] * coeff_a[6 ];
501  right += hist_b[i - 11] * coeff_b[ 6] - hist_a[i - 11] * coeff_a[6 ];
502  left += hist_b[i - 14] * coeff_b[ 7] - hist_a[i - 14] * coeff_a[7 ];
503  right += hist_b[i - 13] * coeff_b[ 7] - hist_a[i - 13] * coeff_a[7 ];
504  left += hist_b[i - 16] * coeff_b[ 8] - hist_a[i - 16] * coeff_a[8 ];
505  right += hist_b[i - 15] * coeff_b[ 8] - hist_a[i - 15] * coeff_a[8 ];
506  left += hist_b[i - 18] * coeff_b[ 9] - hist_a[i - 18] * coeff_a[9 ];
507  right += hist_b[i - 17] * coeff_b[ 9] - hist_a[i - 17] * coeff_a[9 ];
508  left += hist_b[i - 20] * coeff_b[10] - hist_a[i - 20] * coeff_a[10];
509  right += hist_b[i - 19] * coeff_b[10] - hist_a[i - 19] * coeff_a[10];
510  dst[0] = hist_a[i ] = (float)left;
511  dst[1] = hist_a[i + 1] = (float)right;
512  src += 2;
513  dst += 2;
514 
515  if ((i += 2) == 256) {
516  memcpy(hist_a, hist_a + 236, sizeof(*hist_a) * 20);
517  memcpy(hist_b, hist_b + 236, sizeof(*hist_b) * 20);
518  i = 20;
519  }
520  }
521 
522  s->yule_hist_i = i;
523 }
524 
525 /*
526  * Calculate the ReplayGain value from the specified loudness histogram;
527  * clip to -24 / +64 dB.
528  */
529 static float calc_replaygain(uint32_t *histogram)
530 {
531  uint32_t loud_count = 0, total_windows = 0;
532  float gain;
533  int i;
534 
535  for (i = 0; i < HISTOGRAM_SLOTS; i++)
536  total_windows += histogram [i];
537 
538  while (i--)
539  if ((loud_count += histogram [i]) * 20 >= total_windows)
540  break;
541 
542  gain = (float)(64.54 - i / 100.0);
543 
544  return av_clipf(gain, -24.0, 64.0);
545 }
546 
547 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
548 {
549  AVFilterContext *ctx = inlink->dst;
550  AVFilterLink *outlink = ctx->outputs[0];
551  ReplayGainContext *s = ctx->priv;
552  uint32_t level;
553  AVFrame *out;
554 
555  out = ff_get_audio_buffer(inlink, in->nb_samples);
556  if (!out) {
557  av_frame_free(&in);
558  return AVERROR(ENOMEM);
559  }
560 
561  calc_stereo_peak((float *)in->data[0],
562  in->nb_samples, &s->peak);
563  yule_filter_stereo_samples(s, (const float *)in->data[0],
564  (float *)out->data[0],
565  out->nb_samples);
566  butter_filter_stereo_samples(s, (float *)out->data[0],
567  out->nb_samples);
568  level = (uint32_t)floor(100 * calc_stereo_rms((float *)out->data[0],
569  out->nb_samples));
570  level = av_clip(level, 0, HISTOGRAM_SLOTS - 1);
571 
572  s->histogram[level]++;
573 
574  av_frame_free(&out);
575  return ff_filter_frame(outlink, in);
576 }
577 
578 static av_cold void uninit(AVFilterContext *ctx)
579 {
580  ReplayGainContext *s = ctx->priv;
581  float gain = calc_replaygain(s->histogram);
582 
583  av_log(ctx, AV_LOG_INFO, "track_gain = %+.2f dB\n", gain);
584  av_log(ctx, AV_LOG_INFO, "track_peak = %.6f\n", s->peak);
585 }
586 
587 static const AVFilterPad replaygain_inputs[] = {
588  {
589  .name = "default",
590  .type = AVMEDIA_TYPE_AUDIO,
591  .filter_frame = filter_frame,
592  .config_props = config_input,
593  },
594  { NULL }
595 };
596 
597 static const AVFilterPad replaygain_outputs[] = {
598  {
599  .name = "default",
600  .type = AVMEDIA_TYPE_AUDIO,
601  },
602  { NULL }
603 };
604 
606  .name = "replaygain",
607  .description = NULL_IF_CONFIG_SMALL("ReplayGain scanner."),
608  .query_formats = query_formats,
609  .uninit = uninit,
610  .priv_size = sizeof(ReplayGainContext),
611  .inputs = replaygain_inputs,
612  .outputs = replaygain_outputs,
613 };