aacpsy.c
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1 /*
2  * AAC encoder psychoacoustic model
3  * Copyright (C) 2008 Konstantin Shishkov
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 
27 #include "avcodec.h"
28 #include "aactab.h"
29 #include "psymodel.h"
30 
31 /***********************************
32  * TODOs:
33  * try other bitrate controlling mechanism (maybe use ratecontrol.c?)
34  * control quality for quality-based output
35  **********************************/
36 
41 #define PSY_3GPP_THR_SPREAD_HI 1.5f // spreading factor for low-to-hi threshold spreading (15 dB/Bark)
42 #define PSY_3GPP_THR_SPREAD_LOW 3.0f // spreading factor for hi-to-low threshold spreading (30 dB/Bark)
43 /* spreading factor for low-to-hi energy spreading, long block, > 22kbps/channel (20dB/Bark) */
44 #define PSY_3GPP_EN_SPREAD_HI_L1 2.0f
45 /* spreading factor for low-to-hi energy spreading, long block, <= 22kbps/channel (15dB/Bark) */
46 #define PSY_3GPP_EN_SPREAD_HI_L2 1.5f
47 /* spreading factor for low-to-hi energy spreading, short block (15 dB/Bark) */
48 #define PSY_3GPP_EN_SPREAD_HI_S 1.5f
49 /* spreading factor for hi-to-low energy spreading, long block (30dB/Bark) */
50 #define PSY_3GPP_EN_SPREAD_LOW_L 3.0f
51 /* spreading factor for hi-to-low energy spreading, short block (20dB/Bark) */
52 #define PSY_3GPP_EN_SPREAD_LOW_S 2.0f
53 
54 #define PSY_3GPP_RPEMIN 0.01f
55 #define PSY_3GPP_RPELEV 2.0f
56 
57 #define PSY_3GPP_C1 3.0f /* log2(8) */
58 #define PSY_3GPP_C2 1.3219281f /* log2(2.5) */
59 #define PSY_3GPP_C3 0.55935729f /* 1 - C2 / C1 */
60 
61 #define PSY_SNR_1DB 7.9432821e-1f /* -1dB */
62 #define PSY_SNR_25DB 3.1622776e-3f /* -25dB */
63 
64 #define PSY_3GPP_SAVE_SLOPE_L -0.46666667f
65 #define PSY_3GPP_SAVE_SLOPE_S -0.36363637f
66 #define PSY_3GPP_SAVE_ADD_L -0.84285712f
67 #define PSY_3GPP_SAVE_ADD_S -0.75f
68 #define PSY_3GPP_SPEND_SLOPE_L 0.66666669f
69 #define PSY_3GPP_SPEND_SLOPE_S 0.81818181f
70 #define PSY_3GPP_SPEND_ADD_L -0.35f
71 #define PSY_3GPP_SPEND_ADD_S -0.26111111f
72 #define PSY_3GPP_CLIP_LO_L 0.2f
73 #define PSY_3GPP_CLIP_LO_S 0.2f
74 #define PSY_3GPP_CLIP_HI_L 0.95f
75 #define PSY_3GPP_CLIP_HI_S 0.75f
76 
77 #define PSY_3GPP_AH_THR_LONG 0.5f
78 #define PSY_3GPP_AH_THR_SHORT 0.63f
79 
80 enum {
84 };
85 
86 #define PSY_3GPP_BITS_TO_PE(bits) ((bits) * 1.18f)
87 
88 /* LAME psy model constants */
89 #define PSY_LAME_FIR_LEN 21
90 #define AAC_BLOCK_SIZE_LONG 1024
91 #define AAC_BLOCK_SIZE_SHORT 128
92 #define AAC_NUM_BLOCKS_SHORT 8
93 #define PSY_LAME_NUM_SUBBLOCKS 3
94 
95 
102 typedef struct AacPsyBand{
103  float energy;
104  float thr;
105  float thr_quiet;
106  float nz_lines;
107  float active_lines;
108  float pe;
109  float pe_const;
110  float norm_fac;
112 }AacPsyBand;
113 
117 typedef struct AacPsyChannel{
120 
121  float win_energy;
122  float iir_state[2];
123  uint8_t next_grouping;
125  /* LAME psy model specific members */
130 
134 typedef struct AacPsyCoeffs{
135  float ath;
136  float barks;
137  float spread_low[2];
138  float spread_hi [2];
139  float min_snr;
140 }AacPsyCoeffs;
141 
145 typedef struct AacPsyContext{
149  struct {
150  float min;
151  float max;
152  float previous;
153  float correction;
154  } pe;
158 
162 typedef struct {
163  int quality;
164  /* This is overloaded to be both kbps per channel in ABR mode, and
165  * requested quality in constant quality mode.
166  */
167  float st_lrm;
168 } PsyLamePreset;
169 
173 static const PsyLamePreset psy_abr_map[] = {
174 /* TODO: Tuning. These were taken from LAME. */
175 /* kbps/ch st_lrm */
176  { 8, 6.60},
177  { 16, 6.60},
178  { 24, 6.60},
179  { 32, 6.60},
180  { 40, 6.60},
181  { 48, 6.60},
182  { 56, 6.60},
183  { 64, 6.40},
184  { 80, 6.00},
185  { 96, 5.60},
186  {112, 5.20},
187  {128, 5.20},
188  {160, 5.20}
189 };
190 
194 static const PsyLamePreset psy_vbr_map[] = {
195 /* vbr_q st_lrm */
196  { 0, 4.20},
197  { 1, 4.20},
198  { 2, 4.20},
199  { 3, 4.20},
200  { 4, 4.20},
201  { 5, 4.20},
202  { 6, 4.20},
203  { 7, 4.20},
204  { 8, 4.20},
205  { 9, 4.20},
206  {10, 4.20}
207 };
208 
212 static const float psy_fir_coeffs[] = {
213  -8.65163e-18 * 2, -0.00851586 * 2, -6.74764e-18 * 2, 0.0209036 * 2,
214  -3.36639e-17 * 2, -0.0438162 * 2, -1.54175e-17 * 2, 0.0931738 * 2,
215  -5.52212e-17 * 2, -0.313819 * 2
216 };
217 
221 static float lame_calc_attack_threshold(int bitrate)
222 {
223  /* Assume max bitrate to start with */
224  int lower_range = 12, upper_range = 12;
225  int lower_range_kbps = psy_abr_map[12].quality;
226  int upper_range_kbps = psy_abr_map[12].quality;
227  int i;
228 
229  /* Determine which bitrates the value specified falls between.
230  * If the loop ends without breaking our above assumption of 320kbps was correct.
231  */
232  for (i = 1; i < 13; i++) {
233  if (FFMAX(bitrate, psy_abr_map[i].quality) != bitrate) {
234  upper_range = i;
235  upper_range_kbps = psy_abr_map[i ].quality;
236  lower_range = i - 1;
237  lower_range_kbps = psy_abr_map[i - 1].quality;
238  break; /* Upper range found */
239  }
240  }
241 
242  /* Determine which range the value specified is closer to */
243  if ((upper_range_kbps - bitrate) > (bitrate - lower_range_kbps))
244  return psy_abr_map[lower_range].st_lrm;
245  return psy_abr_map[upper_range].st_lrm;
246 }
247 
251 static void lame_window_init(AacPsyContext *ctx, AVCodecContext *avctx) {
252  int i, j;
253 
254  for (i = 0; i < avctx->channels; i++) {
255  AacPsyChannel *pch = &ctx->ch[i];
256 
257  if (avctx->flags & CODEC_FLAG_QSCALE)
258  pch->attack_threshold = psy_vbr_map[avctx->global_quality / FF_QP2LAMBDA].st_lrm;
259  else
260  pch->attack_threshold = lame_calc_attack_threshold(avctx->bit_rate / avctx->channels / 1000);
261 
262  for (j = 0; j < AAC_NUM_BLOCKS_SHORT * PSY_LAME_NUM_SUBBLOCKS; j++)
263  pch->prev_energy_subshort[j] = 10.0f;
264  }
265 }
266 
270 static av_cold float calc_bark(float f)
271 {
272  return 13.3f * atanf(0.00076f * f) + 3.5f * atanf((f / 7500.0f) * (f / 7500.0f));
273 }
274 
275 #define ATH_ADD 4
276 
280 static av_cold float ath(float f, float add)
281 {
282  f /= 1000.0f;
283  return 3.64 * pow(f, -0.8)
284  - 6.8 * exp(-0.6 * (f - 3.4) * (f - 3.4))
285  + 6.0 * exp(-0.15 * (f - 8.7) * (f - 8.7))
286  + (0.6 + 0.04 * add) * 0.001 * f * f * f * f;
287 }
288 
290  AacPsyContext *pctx;
291  float bark;
292  int i, j, g, start;
293  float prev, minscale, minath, minsnr, pe_min;
294  const int chan_bitrate = ctx->avctx->bit_rate / ctx->avctx->channels;
295  const int bandwidth = ctx->avctx->cutoff ? ctx->avctx->cutoff : ctx->avctx->sample_rate / 2;
296  const float num_bark = calc_bark((float)bandwidth);
297 
298  ctx->model_priv_data = av_mallocz(sizeof(AacPsyContext));
299  pctx = (AacPsyContext*) ctx->model_priv_data;
300 
301  pctx->chan_bitrate = chan_bitrate;
302  pctx->frame_bits = chan_bitrate * AAC_BLOCK_SIZE_LONG / ctx->avctx->sample_rate;
303  pctx->pe.min = 8.0f * AAC_BLOCK_SIZE_LONG * bandwidth / (ctx->avctx->sample_rate * 2.0f);
304  pctx->pe.max = 12.0f * AAC_BLOCK_SIZE_LONG * bandwidth / (ctx->avctx->sample_rate * 2.0f);
305  ctx->bitres.size = 6144 - pctx->frame_bits;
306  ctx->bitres.size -= ctx->bitres.size % 8;
307  pctx->fill_level = ctx->bitres.size;
308  minath = ath(3410, ATH_ADD);
309  for (j = 0; j < 2; j++) {
310  AacPsyCoeffs *coeffs = pctx->psy_coef[j];
311  const uint8_t *band_sizes = ctx->bands[j];
312  float line_to_frequency = ctx->avctx->sample_rate / (j ? 256.f : 2048.0f);
313  float avg_chan_bits = chan_bitrate / ctx->avctx->sample_rate * (j ? 128.0f : 1024.0f);
314  /* reference encoder uses 2.4% here instead of 60% like the spec says */
315  float bark_pe = 0.024f * PSY_3GPP_BITS_TO_PE(avg_chan_bits) / num_bark;
316  float en_spread_low = j ? PSY_3GPP_EN_SPREAD_LOW_S : PSY_3GPP_EN_SPREAD_LOW_L;
317  /* High energy spreading for long blocks <= 22kbps/channel and short blocks are the same. */
318  float en_spread_hi = (j || (chan_bitrate <= 22.0f)) ? PSY_3GPP_EN_SPREAD_HI_S : PSY_3GPP_EN_SPREAD_HI_L1;
319 
320  i = 0;
321  prev = 0.0;
322  for (g = 0; g < ctx->num_bands[j]; g++) {
323  i += band_sizes[g];
324  bark = calc_bark((i-1) * line_to_frequency);
325  coeffs[g].barks = (bark + prev) / 2.0;
326  prev = bark;
327  }
328  for (g = 0; g < ctx->num_bands[j] - 1; g++) {
329  AacPsyCoeffs *coeff = &coeffs[g];
330  float bark_width = coeffs[g+1].barks - coeffs->barks;
331  coeff->spread_low[0] = pow(10.0, -bark_width * PSY_3GPP_THR_SPREAD_LOW);
332  coeff->spread_hi [0] = pow(10.0, -bark_width * PSY_3GPP_THR_SPREAD_HI);
333  coeff->spread_low[1] = pow(10.0, -bark_width * en_spread_low);
334  coeff->spread_hi [1] = pow(10.0, -bark_width * en_spread_hi);
335  pe_min = bark_pe * bark_width;
336  minsnr = pow(2.0f, pe_min / band_sizes[g]) - 1.5f;
337  coeff->min_snr = av_clipf(1.0f / minsnr, PSY_SNR_25DB, PSY_SNR_1DB);
338  }
339  start = 0;
340  for (g = 0; g < ctx->num_bands[j]; g++) {
341  minscale = ath(start * line_to_frequency, ATH_ADD);
342  for (i = 1; i < band_sizes[g]; i++)
343  minscale = FFMIN(minscale, ath((start + i) * line_to_frequency, ATH_ADD));
344  coeffs[g].ath = minscale - minath;
345  start += band_sizes[g];
346  }
347  }
348 
349  pctx->ch = av_mallocz(sizeof(AacPsyChannel) * ctx->avctx->channels);
350 
351  lame_window_init(pctx, ctx->avctx);
352 
353  return 0;
354 }
355 
359 static float iir_filter(int in, float state[2])
360 {
361  float ret;
362 
363  ret = 0.7548f * (in - state[0]) + 0.5095f * state[1];
364  state[0] = in;
365  state[1] = ret;
366  return ret;
367 }
368 
372 static const uint8_t window_grouping[9] = {
373  0xB6, 0x6C, 0xD8, 0xB2, 0x66, 0xC6, 0x96, 0x36, 0x36
374 };
375 
381  const int16_t *audio,
382  const int16_t *la,
383  int channel, int prev_type)
384 {
385  int i, j;
386  int br = ctx->avctx->bit_rate / ctx->avctx->channels;
387  int attack_ratio = br <= 16000 ? 18 : 10;
389  AacPsyChannel *pch = &pctx->ch[channel];
390  uint8_t grouping = 0;
391  int next_type = pch->next_window_seq;
392  FFPsyWindowInfo wi;
393 
394  memset(&wi, 0, sizeof(wi));
395  if (la) {
396  float s[8], v;
397  int switch_to_eight = 0;
398  float sum = 0.0, sum2 = 0.0;
399  int attack_n = 0;
400  int stay_short = 0;
401  for (i = 0; i < 8; i++) {
402  for (j = 0; j < 128; j++) {
403  v = iir_filter(la[(i*128+j)*ctx->avctx->channels], pch->iir_state);
404  sum += v*v;
405  }
406  s[i] = sum;
407  sum2 += sum;
408  }
409  for (i = 0; i < 8; i++) {
410  if (s[i] > pch->win_energy * attack_ratio) {
411  attack_n = i + 1;
412  switch_to_eight = 1;
413  break;
414  }
415  }
416  pch->win_energy = pch->win_energy*7/8 + sum2/64;
417 
418  wi.window_type[1] = prev_type;
419  switch (prev_type) {
420  case ONLY_LONG_SEQUENCE:
421  wi.window_type[0] = switch_to_eight ? LONG_START_SEQUENCE : ONLY_LONG_SEQUENCE;
422  next_type = switch_to_eight ? EIGHT_SHORT_SEQUENCE : ONLY_LONG_SEQUENCE;
423  break;
424  case LONG_START_SEQUENCE:
425  wi.window_type[0] = EIGHT_SHORT_SEQUENCE;
426  grouping = pch->next_grouping;
427  next_type = switch_to_eight ? EIGHT_SHORT_SEQUENCE : LONG_STOP_SEQUENCE;
428  break;
429  case LONG_STOP_SEQUENCE:
430  wi.window_type[0] = switch_to_eight ? LONG_START_SEQUENCE : ONLY_LONG_SEQUENCE;
431  next_type = switch_to_eight ? EIGHT_SHORT_SEQUENCE : ONLY_LONG_SEQUENCE;
432  break;
434  stay_short = next_type == EIGHT_SHORT_SEQUENCE || switch_to_eight;
435  wi.window_type[0] = stay_short ? EIGHT_SHORT_SEQUENCE : LONG_STOP_SEQUENCE;
436  grouping = next_type == EIGHT_SHORT_SEQUENCE ? pch->next_grouping : 0;
437  next_type = switch_to_eight ? EIGHT_SHORT_SEQUENCE : LONG_STOP_SEQUENCE;
438  break;
439  }
440 
441  pch->next_grouping = window_grouping[attack_n];
442  pch->next_window_seq = next_type;
443  } else {
444  for (i = 0; i < 3; i++)
445  wi.window_type[i] = prev_type;
446  grouping = (prev_type == EIGHT_SHORT_SEQUENCE) ? window_grouping[0] : 0;
447  }
448 
449  wi.window_shape = 1;
450  if (wi.window_type[0] != EIGHT_SHORT_SEQUENCE) {
451  wi.num_windows = 1;
452  wi.grouping[0] = 1;
453  } else {
454  int lastgrp = 0;
455  wi.num_windows = 8;
456  for (i = 0; i < 8; i++) {
457  if (!((grouping >> i) & 1))
458  lastgrp = i;
459  wi.grouping[lastgrp]++;
460  }
461  }
462 
463  return wi;
464 }
465 
466 /* 5.6.1.2 "Calculation of Bit Demand" */
467 static int calc_bit_demand(AacPsyContext *ctx, float pe, int bits, int size,
468  int short_window)
469 {
470  const float bitsave_slope = short_window ? PSY_3GPP_SAVE_SLOPE_S : PSY_3GPP_SAVE_SLOPE_L;
471  const float bitsave_add = short_window ? PSY_3GPP_SAVE_ADD_S : PSY_3GPP_SAVE_ADD_L;
472  const float bitspend_slope = short_window ? PSY_3GPP_SPEND_SLOPE_S : PSY_3GPP_SPEND_SLOPE_L;
473  const float bitspend_add = short_window ? PSY_3GPP_SPEND_ADD_S : PSY_3GPP_SPEND_ADD_L;
474  const float clip_low = short_window ? PSY_3GPP_CLIP_LO_S : PSY_3GPP_CLIP_LO_L;
475  const float clip_high = short_window ? PSY_3GPP_CLIP_HI_S : PSY_3GPP_CLIP_HI_L;
476  float clipped_pe, bit_save, bit_spend, bit_factor, fill_level;
477 
478  ctx->fill_level += ctx->frame_bits - bits;
479  ctx->fill_level = av_clip(ctx->fill_level, 0, size);
480  fill_level = av_clipf((float)ctx->fill_level / size, clip_low, clip_high);
481  clipped_pe = av_clipf(pe, ctx->pe.min, ctx->pe.max);
482  bit_save = (fill_level + bitsave_add) * bitsave_slope;
483  assert(bit_save <= 0.3f && bit_save >= -0.05000001f);
484  bit_spend = (fill_level + bitspend_add) * bitspend_slope;
485  assert(bit_spend <= 0.5f && bit_spend >= -0.1f);
486  /* The bit factor graph in the spec is obviously incorrect.
487  * bit_spend + ((bit_spend - bit_spend))...
488  * The reference encoder subtracts everything from 1, but also seems incorrect.
489  * 1 - bit_save + ((bit_spend + bit_save))...
490  * Hopefully below is correct.
491  */
492  bit_factor = 1.0f - bit_save + ((bit_spend - bit_save) / (ctx->pe.max - ctx->pe.min)) * (clipped_pe - ctx->pe.min);
493  /* NOTE: The reference encoder attempts to center pe max/min around the current pe. */
494  ctx->pe.max = FFMAX(pe, ctx->pe.max);
495  ctx->pe.min = FFMIN(pe, ctx->pe.min);
496 
497  return FFMIN(ctx->frame_bits * bit_factor, ctx->frame_bits + size - bits);
498 }
499 
500 static float calc_pe_3gpp(AacPsyBand *band)
501 {
502  float pe, a;
503 
504  band->pe = 0.0f;
505  band->pe_const = 0.0f;
506  band->active_lines = 0.0f;
507  if (band->energy > band->thr) {
508  a = log2f(band->energy);
509  pe = a - log2f(band->thr);
510  band->active_lines = band->nz_lines;
511  if (pe < PSY_3GPP_C1) {
512  pe = pe * PSY_3GPP_C3 + PSY_3GPP_C2;
513  a = a * PSY_3GPP_C3 + PSY_3GPP_C2;
514  band->active_lines *= PSY_3GPP_C3;
515  }
516  band->pe = pe * band->nz_lines;
517  band->pe_const = a * band->nz_lines;
518  }
519 
520  return band->pe;
521 }
522 
523 static float calc_reduction_3gpp(float a, float desired_pe, float pe,
524  float active_lines)
525 {
526  float thr_avg, reduction;
527 
528  thr_avg = powf(2.0f, (a - pe) / (4.0f * active_lines));
529  reduction = powf(2.0f, (a - desired_pe) / (4.0f * active_lines)) - thr_avg;
530 
531  return FFMAX(reduction, 0.0f);
532 }
533 
534 static float calc_reduced_thr_3gpp(AacPsyBand *band, float min_snr,
535  float reduction)
536 {
537  float thr = band->thr;
538 
539  if (band->energy > thr) {
540  thr = powf(thr, 0.25f) + reduction;
541  thr = powf(thr, 4.0f);
542 
543  /* This deviates from the 3GPP spec to match the reference encoder.
544  * It performs min(thr_reduced, max(thr, energy/min_snr)) only for bands
545  * that have hole avoidance on (active or inactive). It always reduces the
546  * threshold of bands with hole avoidance off.
547  */
548  if (thr > band->energy * min_snr && band->avoid_holes != PSY_3GPP_AH_NONE) {
549  thr = FFMAX(band->thr, band->energy * min_snr);
551  }
552  }
553 
554  return thr;
555 }
556 
560 static void psy_3gpp_analyze_channel(FFPsyContext *ctx, int channel,
561  const float *coefs, const FFPsyWindowInfo *wi)
562 {
564  AacPsyChannel *pch = &pctx->ch[channel];
565  int start = 0;
566  int i, w, g;
567  float desired_bits, desired_pe, delta_pe, reduction, spread_en[128] = {0};
568  float a = 0.0f, active_lines = 0.0f, norm_fac = 0.0f;
569  float pe = pctx->chan_bitrate > 32000 ? 0.0f : FFMAX(50.0f, 100.0f - pctx->chan_bitrate * 100.0f / 32000.0f);
570  const int num_bands = ctx->num_bands[wi->num_windows == 8];
571  const uint8_t *band_sizes = ctx->bands[wi->num_windows == 8];
572  AacPsyCoeffs *coeffs = pctx->psy_coef[wi->num_windows == 8];
573  const float avoid_hole_thr = wi->num_windows == 8 ? PSY_3GPP_AH_THR_SHORT : PSY_3GPP_AH_THR_LONG;
574 
575  //calculate energies, initial thresholds and related values - 5.4.2 "Threshold Calculation"
576  for (w = 0; w < wi->num_windows*16; w += 16) {
577  for (g = 0; g < num_bands; g++) {
578  AacPsyBand *band = &pch->band[w+g];
579 
580  float form_factor = 0.0f;
581  band->energy = 0.0f;
582  for (i = 0; i < band_sizes[g]; i++) {
583  band->energy += coefs[start+i] * coefs[start+i];
584  form_factor += sqrtf(fabs(coefs[start+i]));
585  }
586  band->thr = band->energy * 0.001258925f;
587  band->nz_lines = form_factor / powf(band->energy / band_sizes[g], 0.25f);
588 
589  start += band_sizes[g];
590  }
591  }
592  //modify thresholds and energies - spread, threshold in quiet, pre-echo control
593  for (w = 0; w < wi->num_windows*16; w += 16) {
594  AacPsyBand *bands = &pch->band[w];
595 
596  //5.4.2.3 "Spreading" & 5.4.3 "Spreaded Energy Calculation"
597  spread_en[0] = bands[0].energy;
598  for (g = 1; g < num_bands; g++) {
599  bands[g].thr = FFMAX(bands[g].thr, bands[g-1].thr * coeffs[g].spread_hi[0]);
600  spread_en[w+g] = FFMAX(bands[g].energy, spread_en[w+g-1] * coeffs[g].spread_hi[1]);
601  }
602  for (g = num_bands - 2; g >= 0; g--) {
603  bands[g].thr = FFMAX(bands[g].thr, bands[g+1].thr * coeffs[g].spread_low[0]);
604  spread_en[w+g] = FFMAX(spread_en[w+g], spread_en[w+g+1] * coeffs[g].spread_low[1]);
605  }
606  //5.4.2.4 "Threshold in quiet"
607  for (g = 0; g < num_bands; g++) {
608  AacPsyBand *band = &bands[g];
609 
610  band->thr_quiet = band->thr = FFMAX(band->thr, coeffs[g].ath);
611  //5.4.2.5 "Pre-echo control"
612  if (!(wi->window_type[0] == LONG_STOP_SEQUENCE || (wi->window_type[1] == LONG_START_SEQUENCE && !w)))
613  band->thr = FFMAX(PSY_3GPP_RPEMIN*band->thr, FFMIN(band->thr,
614  PSY_3GPP_RPELEV*pch->prev_band[w+g].thr_quiet));
615 
616  /* 5.6.1.3.1 "Prepatory steps of the perceptual entropy calculation" */
617  pe += calc_pe_3gpp(band);
618  a += band->pe_const;
619  active_lines += band->active_lines;
620 
621  /* 5.6.1.3.3 "Selection of the bands for avoidance of holes" */
622  if (spread_en[w+g] * avoid_hole_thr > band->energy || coeffs[g].min_snr > 1.0f)
624  else
626  }
627  }
628 
629  /* 5.6.1.3.2 "Calculation of the desired perceptual entropy" */
630  ctx->ch[channel].entropy = pe;
631  desired_bits = calc_bit_demand(pctx, pe, ctx->bitres.bits, ctx->bitres.size, wi->num_windows == 8);
632  desired_pe = PSY_3GPP_BITS_TO_PE(desired_bits);
633  /* NOTE: PE correction is kept simple. During initial testing it had very
634  * little effect on the final bitrate. Probably a good idea to come
635  * back and do more testing later.
636  */
637  if (ctx->bitres.bits > 0)
638  desired_pe *= av_clipf(pctx->pe.previous / PSY_3GPP_BITS_TO_PE(ctx->bitres.bits),
639  0.85f, 1.15f);
640  pctx->pe.previous = PSY_3GPP_BITS_TO_PE(desired_bits);
641 
642  if (desired_pe < pe) {
643  /* 5.6.1.3.4 "First Estimation of the reduction value" */
644  for (w = 0; w < wi->num_windows*16; w += 16) {
645  reduction = calc_reduction_3gpp(a, desired_pe, pe, active_lines);
646  pe = 0.0f;
647  a = 0.0f;
648  active_lines = 0.0f;
649  for (g = 0; g < num_bands; g++) {
650  AacPsyBand *band = &pch->band[w+g];
651 
652  band->thr = calc_reduced_thr_3gpp(band, coeffs[g].min_snr, reduction);
653  /* recalculate PE */
654  pe += calc_pe_3gpp(band);
655  a += band->pe_const;
656  active_lines += band->active_lines;
657  }
658  }
659 
660  /* 5.6.1.3.5 "Second Estimation of the reduction value" */
661  for (i = 0; i < 2; i++) {
662  float pe_no_ah = 0.0f, desired_pe_no_ah;
663  active_lines = a = 0.0f;
664  for (w = 0; w < wi->num_windows*16; w += 16) {
665  for (g = 0; g < num_bands; g++) {
666  AacPsyBand *band = &pch->band[w+g];
667 
668  if (band->avoid_holes != PSY_3GPP_AH_ACTIVE) {
669  pe_no_ah += band->pe;
670  a += band->pe_const;
671  active_lines += band->active_lines;
672  }
673  }
674  }
675  desired_pe_no_ah = FFMAX(desired_pe - (pe - pe_no_ah), 0.0f);
676  if (active_lines > 0.0f)
677  reduction += calc_reduction_3gpp(a, desired_pe_no_ah, pe_no_ah, active_lines);
678 
679  pe = 0.0f;
680  for (w = 0; w < wi->num_windows*16; w += 16) {
681  for (g = 0; g < num_bands; g++) {
682  AacPsyBand *band = &pch->band[w+g];
683 
684  if (active_lines > 0.0f)
685  band->thr = calc_reduced_thr_3gpp(band, coeffs[g].min_snr, reduction);
686  pe += calc_pe_3gpp(band);
687  band->norm_fac = band->active_lines / band->thr;
688  norm_fac += band->norm_fac;
689  }
690  }
691  delta_pe = desired_pe - pe;
692  if (fabs(delta_pe) > 0.05f * desired_pe)
693  break;
694  }
695 
696  if (pe < 1.15f * desired_pe) {
697  /* 6.6.1.3.6 "Final threshold modification by linearization" */
698  norm_fac = 1.0f / norm_fac;
699  for (w = 0; w < wi->num_windows*16; w += 16) {
700  for (g = 0; g < num_bands; g++) {
701  AacPsyBand *band = &pch->band[w+g];
702 
703  if (band->active_lines > 0.5f) {
704  float delta_sfb_pe = band->norm_fac * norm_fac * delta_pe;
705  float thr = band->thr;
706 
707  thr *= powf(2.0f, delta_sfb_pe / band->active_lines);
708  if (thr > coeffs[g].min_snr * band->energy && band->avoid_holes == PSY_3GPP_AH_INACTIVE)
709  thr = FFMAX(band->thr, coeffs[g].min_snr * band->energy);
710  band->thr = thr;
711  }
712  }
713  }
714  } else {
715  /* 5.6.1.3.7 "Further perceptual entropy reduction" */
716  g = num_bands;
717  while (pe > desired_pe && g--) {
718  for (w = 0; w < wi->num_windows*16; w+= 16) {
719  AacPsyBand *band = &pch->band[w+g];
720  if (band->avoid_holes != PSY_3GPP_AH_NONE && coeffs[g].min_snr < PSY_SNR_1DB) {
721  coeffs[g].min_snr = PSY_SNR_1DB;
722  band->thr = band->energy * PSY_SNR_1DB;
723  pe += band->active_lines * 1.5f - band->pe;
724  }
725  }
726  }
727  /* TODO: allow more holes (unused without mid/side) */
728  }
729  }
730 
731  for (w = 0; w < wi->num_windows*16; w += 16) {
732  for (g = 0; g < num_bands; g++) {
733  AacPsyBand *band = &pch->band[w+g];
734  FFPsyBand *psy_band = &ctx->ch[channel].psy_bands[w+g];
735 
736  psy_band->threshold = band->thr;
737  psy_band->energy = band->energy;
738  }
739  }
740 
741  memcpy(pch->prev_band, pch->band, sizeof(pch->band));
742 }
743 
744 static void psy_3gpp_analyze(FFPsyContext *ctx, int channel,
745  const float **coeffs, const FFPsyWindowInfo *wi)
746 {
747  int ch;
748  FFPsyChannelGroup *group = ff_psy_find_group(ctx, channel);
749 
750  for (ch = 0; ch < group->num_ch; ch++)
751  psy_3gpp_analyze_channel(ctx, channel + ch, coeffs[ch], &wi[ch]);
752 }
753 
755 {
757  av_freep(&pctx->ch);
758  av_freep(&apc->model_priv_data);
759 }
760 
761 static void lame_apply_block_type(AacPsyChannel *ctx, FFPsyWindowInfo *wi, int uselongblock)
762 {
763  int blocktype = ONLY_LONG_SEQUENCE;
764  if (uselongblock) {
766  blocktype = LONG_STOP_SEQUENCE;
767  } else {
768  blocktype = EIGHT_SHORT_SEQUENCE;
773  }
774 
775  wi->window_type[0] = ctx->next_window_seq;
776  ctx->next_window_seq = blocktype;
777 }
778 
780  const int16_t *audio, const int16_t *la,
781  int channel, int prev_type)
782 {
784  AacPsyChannel *pch = &pctx->ch[channel];
785  int grouping = 0;
786  int uselongblock = 1;
787  int attacks[AAC_NUM_BLOCKS_SHORT + 1] = { 0 };
788  int i;
789  FFPsyWindowInfo wi;
790 
791  memset(&wi, 0, sizeof(wi));
792  if (la) {
793  float hpfsmpl[AAC_BLOCK_SIZE_LONG];
794  float const *pf = hpfsmpl;
795  float attack_intensity[(AAC_NUM_BLOCKS_SHORT + 1) * PSY_LAME_NUM_SUBBLOCKS];
796  float energy_subshort[(AAC_NUM_BLOCKS_SHORT + 1) * PSY_LAME_NUM_SUBBLOCKS];
797  float energy_short[AAC_NUM_BLOCKS_SHORT + 1] = { 0 };
798  int chans = ctx->avctx->channels;
799  const int16_t *firbuf = la + (AAC_BLOCK_SIZE_SHORT/4 - PSY_LAME_FIR_LEN) * chans;
800  int j, att_sum = 0;
801 
802  /* LAME comment: apply high pass filter of fs/4 */
803  for (i = 0; i < AAC_BLOCK_SIZE_LONG; i++) {
804  float sum1, sum2;
805  sum1 = firbuf[(i + ((PSY_LAME_FIR_LEN - 1) / 2)) * chans];
806  sum2 = 0.0;
807  for (j = 0; j < ((PSY_LAME_FIR_LEN - 1) / 2) - 1; j += 2) {
808  sum1 += psy_fir_coeffs[j] * (firbuf[(i + j) * chans] + firbuf[(i + PSY_LAME_FIR_LEN - j) * chans]);
809  sum2 += psy_fir_coeffs[j + 1] * (firbuf[(i + j + 1) * chans] + firbuf[(i + PSY_LAME_FIR_LEN - j - 1) * chans]);
810  }
811  hpfsmpl[i] = sum1 + sum2;
812  }
813 
814  /* Calculate the energies of each sub-shortblock */
815  for (i = 0; i < PSY_LAME_NUM_SUBBLOCKS; i++) {
816  energy_subshort[i] = pch->prev_energy_subshort[i + ((AAC_NUM_BLOCKS_SHORT - 1) * PSY_LAME_NUM_SUBBLOCKS)];
817  assert(pch->prev_energy_subshort[i + ((AAC_NUM_BLOCKS_SHORT - 2) * PSY_LAME_NUM_SUBBLOCKS + 1)] > 0);
818  attack_intensity[i] = energy_subshort[i] / pch->prev_energy_subshort[i + ((AAC_NUM_BLOCKS_SHORT - 2) * PSY_LAME_NUM_SUBBLOCKS + 1)];
819  energy_short[0] += energy_subshort[i];
820  }
821 
822  for (i = 0; i < AAC_NUM_BLOCKS_SHORT * PSY_LAME_NUM_SUBBLOCKS; i++) {
823  float const *const pfe = pf + AAC_BLOCK_SIZE_LONG / (AAC_NUM_BLOCKS_SHORT * PSY_LAME_NUM_SUBBLOCKS);
824  float p = 1.0f;
825  for (; pf < pfe; pf++)
826  if (p < fabsf(*pf))
827  p = fabsf(*pf);
828  pch->prev_energy_subshort[i] = energy_subshort[i + PSY_LAME_NUM_SUBBLOCKS] = p;
829  energy_short[1 + i / PSY_LAME_NUM_SUBBLOCKS] += p;
830  /* FIXME: The indexes below are [i + 3 - 2] in the LAME source.
831  * Obviously the 3 and 2 have some significance, or this would be just [i + 1]
832  * (which is what we use here). What the 3 stands for is ambigious, as it is both
833  * number of short blocks, and the number of sub-short blocks.
834  * It seems that LAME is comparing each sub-block to sub-block + 1 in the
835  * previous block.
836  */
837  if (p > energy_subshort[i + 1])
838  p = p / energy_subshort[i + 1];
839  else if (energy_subshort[i + 1] > p * 10.0f)
840  p = energy_subshort[i + 1] / (p * 10.0f);
841  else
842  p = 0.0;
843  attack_intensity[i + PSY_LAME_NUM_SUBBLOCKS] = p;
844  }
845 
846  /* compare energy between sub-short blocks */
847  for (i = 0; i < (AAC_NUM_BLOCKS_SHORT + 1) * PSY_LAME_NUM_SUBBLOCKS; i++)
848  if (!attacks[i / PSY_LAME_NUM_SUBBLOCKS])
849  if (attack_intensity[i] > pch->attack_threshold)
850  attacks[i / PSY_LAME_NUM_SUBBLOCKS] = (i % PSY_LAME_NUM_SUBBLOCKS) + 1;
851 
852  /* should have energy change between short blocks, in order to avoid periodic signals */
853  /* Good samples to show the effect are Trumpet test songs */
854  /* GB: tuned (1) to avoid too many short blocks for test sample TRUMPET */
855  /* RH: tuned (2) to let enough short blocks through for test sample FSOL and SNAPS */
856  for (i = 1; i < AAC_NUM_BLOCKS_SHORT + 1; i++) {
857  float const u = energy_short[i - 1];
858  float const v = energy_short[i];
859  float const m = FFMAX(u, v);
860  if (m < 40000) { /* (2) */
861  if (u < 1.7f * v && v < 1.7f * u) { /* (1) */
862  if (i == 1 && attacks[0] < attacks[i])
863  attacks[0] = 0;
864  attacks[i] = 0;
865  }
866  }
867  att_sum += attacks[i];
868  }
869 
870  if (attacks[0] <= pch->prev_attack)
871  attacks[0] = 0;
872 
873  att_sum += attacks[0];
874  /* 3 below indicates the previous attack happened in the last sub-block of the previous sequence */
875  if (pch->prev_attack == 3 || att_sum) {
876  uselongblock = 0;
877 
878  for (i = 1; i < AAC_NUM_BLOCKS_SHORT + 1; i++)
879  if (attacks[i] && attacks[i-1])
880  attacks[i] = 0;
881  }
882  } else {
883  /* We have no lookahead info, so just use same type as the previous sequence. */
884  uselongblock = !(prev_type == EIGHT_SHORT_SEQUENCE);
885  }
886 
887  lame_apply_block_type(pch, &wi, uselongblock);
888 
889  wi.window_type[1] = prev_type;
890  if (wi.window_type[0] != EIGHT_SHORT_SEQUENCE) {
891  wi.num_windows = 1;
892  wi.grouping[0] = 1;
893  if (wi.window_type[0] == LONG_START_SEQUENCE)
894  wi.window_shape = 0;
895  else
896  wi.window_shape = 1;
897  } else {
898  int lastgrp = 0;
899 
900  wi.num_windows = 8;
901  wi.window_shape = 0;
902  for (i = 0; i < 8; i++) {
903  if (!((pch->next_grouping >> i) & 1))
904  lastgrp = i;
905  wi.grouping[lastgrp]++;
906  }
907  }
908 
909  /* Determine grouping, based on the location of the first attack, and save for
910  * the next frame.
911  * FIXME: Move this to analysis.
912  * TODO: Tune groupings depending on attack location
913  * TODO: Handle more than one attack in a group
914  */
915  for (i = 0; i < 9; i++) {
916  if (attacks[i]) {
917  grouping = i;
918  break;
919  }
920  }
921  pch->next_grouping = window_grouping[grouping];
922 
923  pch->prev_attack = attacks[8];
924 
925  return wi;
926 }
927 
929 {
930  .name = "3GPP TS 26.403-inspired model",
931  .init = psy_3gpp_init,
932  .window = psy_lame_window,
933  .analyze = psy_3gpp_analyze,
934  .end = psy_3gpp_end,
935 };