summaryrefslogtreecommitdiff
path: root/libavcodec/aaccoder.c
blob: bca1f597ca10053badfa8ad5b9e7f978a6540571 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
/*
 * AAC coefficients encoder
 * Copyright (C) 2008-2009 Konstantin Shishkov
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * AAC coefficients encoder
 */

/***********************************
 *              TODOs:
 * speedup quantizer selection
 * add sane pulse detection
 ***********************************/

#include "libavutil/libm.h" // brought forward to work around cygwin header breakage

#include <float.h>

#include "libavutil/mathematics.h"
#include "mathops.h"
#include "avcodec.h"
#include "put_bits.h"
#include "aac.h"
#include "aacenc.h"
#include "aactab.h"
#include "aacenctab.h"
#include "aacenc_utils.h"
#include "aacenc_quantization.h"

#include "aacenc_is.h"
#include "aacenc_tns.h"
#include "aacenc_ltp.h"
#include "aacenc_pred.h"

#include "libavcodec/aaccoder_twoloop.h"

/* Parameter of f(x) = a*(lambda/100), defines the maximum fourier spread
 * beyond which no PNS is used (since the SFBs contain tone rather than noise) */
#define NOISE_SPREAD_THRESHOLD 0.9f

/* Parameter of f(x) = a*(100/lambda), defines how much PNS is allowed to
 * replace low energy non zero bands */
#define NOISE_LAMBDA_REPLACE 1.948f

#include "libavcodec/aaccoder_trellis.h"

/**
 * structure used in optimal codebook search
 */
typedef struct BandCodingPath {
    int prev_idx; ///< pointer to the previous path point
    float cost;   ///< path cost
    int run;
} BandCodingPath;

/**
 * Encode band info for single window group bands.
 */
static void encode_window_bands_info(AACEncContext *s, SingleChannelElement *sce,
                                     int win, int group_len, const float lambda)
{
    BandCodingPath path[120][CB_TOT_ALL];
    int w, swb, cb, start, size;
    int i, j;
    const int max_sfb  = sce->ics.max_sfb;
    const int run_bits = sce->ics.num_windows == 1 ? 5 : 3;
    const int run_esc  = (1 << run_bits) - 1;
    int idx, ppos, count;
    int stackrun[120], stackcb[120], stack_len;
    float next_minrd = INFINITY;
    int next_mincb = 0;

    abs_pow34_v(s->scoefs, sce->coeffs, 1024);
    start = win*128;
    for (cb = 0; cb < CB_TOT_ALL; cb++) {
        path[0][cb].cost     = 0.0f;
        path[0][cb].prev_idx = -1;
        path[0][cb].run      = 0;
    }
    for (swb = 0; swb < max_sfb; swb++) {
        size = sce->ics.swb_sizes[swb];
        if (sce->zeroes[win*16 + swb]) {
            for (cb = 0; cb < CB_TOT_ALL; cb++) {
                path[swb+1][cb].prev_idx = cb;
                path[swb+1][cb].cost     = path[swb][cb].cost;
                path[swb+1][cb].run      = path[swb][cb].run + 1;
            }
        } else {
            float minrd = next_minrd;
            int mincb = next_mincb;
            next_minrd = INFINITY;
            next_mincb = 0;
            for (cb = 0; cb < CB_TOT_ALL; cb++) {
                float cost_stay_here, cost_get_here;
                float rd = 0.0f;
                if (cb >= 12 && sce->band_type[win*16+swb] < aac_cb_out_map[cb] ||
                    cb  < aac_cb_in_map[sce->band_type[win*16+swb]] && sce->band_type[win*16+swb] > aac_cb_out_map[cb]) {
                    path[swb+1][cb].prev_idx = -1;
                    path[swb+1][cb].cost     = INFINITY;
                    path[swb+1][cb].run      = path[swb][cb].run + 1;
                    continue;
                }
                for (w = 0; w < group_len; w++) {
                    FFPsyBand *band = &s->psy.ch[s->cur_channel].psy_bands[(win+w)*16+swb];
                    rd += quantize_band_cost(s, &sce->coeffs[start + w*128],
                                             &s->scoefs[start + w*128], size,
                                             sce->sf_idx[(win+w)*16+swb], aac_cb_out_map[cb],
                                             lambda / band->threshold, INFINITY, NULL, NULL, 0);
                }
                cost_stay_here = path[swb][cb].cost + rd;
                cost_get_here  = minrd              + rd + run_bits + 4;
                if (   run_value_bits[sce->ics.num_windows == 8][path[swb][cb].run]
                    != run_value_bits[sce->ics.num_windows == 8][path[swb][cb].run+1])
                    cost_stay_here += run_bits;
                if (cost_get_here < cost_stay_here) {
                    path[swb+1][cb].prev_idx = mincb;
                    path[swb+1][cb].cost     = cost_get_here;
                    path[swb+1][cb].run      = 1;
                } else {
                    path[swb+1][cb].prev_idx = cb;
                    path[swb+1][cb].cost     = cost_stay_here;
                    path[swb+1][cb].run      = path[swb][cb].run + 1;
                }
                if (path[swb+1][cb].cost < next_minrd) {
                    next_minrd = path[swb+1][cb].cost;
                    next_mincb = cb;
                }
            }
        }
        start += sce->ics.swb_sizes[swb];
    }

    //convert resulting path from backward-linked list
    stack_len = 0;
    idx       = 0;
    for (cb = 1; cb < CB_TOT_ALL; cb++)
        if (path[max_sfb][cb].cost < path[max_sfb][idx].cost)
            idx = cb;
    ppos = max_sfb;
    while (ppos > 0) {
        av_assert1(idx >= 0);
        cb = idx;
        stackrun[stack_len] = path[ppos][cb].run;
        stackcb [stack_len] = cb;
        idx = path[ppos-path[ppos][cb].run+1][cb].prev_idx;
        ppos -= path[ppos][cb].run;
        stack_len++;
    }
    //perform actual band info encoding
    start = 0;
    for (i = stack_len - 1; i >= 0; i--) {
        cb = aac_cb_out_map[stackcb[i]];
        put_bits(&s->pb, 4, cb);
        count = stackrun[i];
        memset(sce->zeroes + win*16 + start, !cb, count);
        //XXX: memset when band_type is also uint8_t
        for (j = 0; j < count; j++) {
            sce->band_type[win*16 + start] = cb;
            start++;
        }
        while (count >= run_esc) {
            put_bits(&s->pb, run_bits, run_esc);
            count -= run_esc;
        }
        put_bits(&s->pb, run_bits, count);
    }
}


typedef struct TrellisPath {
    float cost;
    int prev;
} TrellisPath;

#define TRELLIS_STAGES 121
#define TRELLIS_STATES (SCALE_MAX_DIFF+1)

static void set_special_band_scalefactors(AACEncContext *s, SingleChannelElement *sce)
{
    int w, g;
    int prevscaler_n = -255, prevscaler_i = 0;
    int bands = 0;

    for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {
        for (g = 0;  g < sce->ics.num_swb; g++) {
            if (sce->zeroes[w*16+g])
                continue;
            if (sce->band_type[w*16+g] == INTENSITY_BT || sce->band_type[w*16+g] == INTENSITY_BT2) {
                sce->sf_idx[w*16+g] = av_clip(roundf(log2f(sce->is_ener[w*16+g])*2), -155, 100);
                bands++;
            } else if (sce->band_type[w*16+g] == NOISE_BT) {
                sce->sf_idx[w*16+g] = av_clip(3+ceilf(log2f(sce->pns_ener[w*16+g])*2), -100, 155);
                if (prevscaler_n == -255)
                    prevscaler_n = sce->sf_idx[w*16+g];
                bands++;
            }
        }
    }

    if (!bands)
        return;

    /* Clip the scalefactor indices */
    for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {
        for (g = 0;  g < sce->ics.num_swb; g++) {
            if (sce->zeroes[w*16+g])
                continue;
            if (sce->band_type[w*16+g] == INTENSITY_BT || sce->band_type[w*16+g] == INTENSITY_BT2) {
                sce->sf_idx[w*16+g] = prevscaler_i = av_clip(sce->sf_idx[w*16+g], prevscaler_i - SCALE_MAX_DIFF, prevscaler_i + SCALE_MAX_DIFF);
            } else if (sce->band_type[w*16+g] == NOISE_BT) {
                sce->sf_idx[w*16+g] = prevscaler_n = av_clip(sce->sf_idx[w*16+g], prevscaler_n - SCALE_MAX_DIFF, prevscaler_n + SCALE_MAX_DIFF);
            }
        }
    }
}

static void search_for_quantizers_anmr(AVCodecContext *avctx, AACEncContext *s,
                                       SingleChannelElement *sce,
                                       const float lambda)
{
    int q, w, w2, g, start = 0;
    int i, j;
    int idx;
    TrellisPath paths[TRELLIS_STAGES][TRELLIS_STATES];
    int bandaddr[TRELLIS_STAGES];
    int minq;
    float mincost;
    float q0f = FLT_MAX, q1f = 0.0f, qnrgf = 0.0f;
    int q0, q1, qcnt = 0;

    for (i = 0; i < 1024; i++) {
        float t = fabsf(sce->coeffs[i]);
        if (t > 0.0f) {
            q0f = FFMIN(q0f, t);
            q1f = FFMAX(q1f, t);
            qnrgf += t*t;
            qcnt++;
        }
    }

    if (!qcnt) {
        memset(sce->sf_idx, 0, sizeof(sce->sf_idx));
        memset(sce->zeroes, 1, sizeof(sce->zeroes));
        return;
    }

    //minimum scalefactor index is when minimum nonzero coefficient after quantizing is not clipped
    q0 = av_clip(coef2minsf(q0f), 0, SCALE_MAX_POS-1);
    //maximum scalefactor index is when maximum coefficient after quantizing is still not zero
    q1 = av_clip(coef2maxsf(q1f), 1, SCALE_MAX_POS);
    if (q1 - q0 > 60) {
        int q0low  = q0;
        int q1high = q1;
        //minimum scalefactor index is when maximum nonzero coefficient after quantizing is not clipped
        int qnrg = av_clip_uint8(log2f(sqrtf(qnrgf/qcnt))*4 - 31 + SCALE_ONE_POS - SCALE_DIV_512);
        q1 = qnrg + 30;
        q0 = qnrg - 30;
        if (q0 < q0low) {
            q1 += q0low - q0;
            q0  = q0low;
        } else if (q1 > q1high) {
            q0 -= q1 - q1high;
            q1  = q1high;
        }
    }
    // q0 == q1 isn't really a legal situation
    if (q0 == q1) {
        // the following is indirect but guarantees q1 != q0 && q1 near q0
        q1 = av_clip(q0+1, 1, SCALE_MAX_POS);
        q0 = av_clip(q1-1, 0, SCALE_MAX_POS - 1);
    }

    for (i = 0; i < TRELLIS_STATES; i++) {
        paths[0][i].cost    = 0.0f;
        paths[0][i].prev    = -1;
    }
    for (j = 1; j < TRELLIS_STAGES; j++) {
        for (i = 0; i < TRELLIS_STATES; i++) {
            paths[j][i].cost    = INFINITY;
            paths[j][i].prev    = -2;
        }
    }
    idx = 1;
    abs_pow34_v(s->scoefs, sce->coeffs, 1024);
    for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {
        start = w*128;
        for (g = 0; g < sce->ics.num_swb; g++) {
            const float *coefs = &sce->coeffs[start];
            float qmin, qmax;
            int nz = 0;

            bandaddr[idx] = w * 16 + g;
            qmin = INT_MAX;
            qmax = 0.0f;
            for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) {
                FFPsyBand *band = &s->psy.ch[s->cur_channel].psy_bands[(w+w2)*16+g];
                if (band->energy <= band->threshold || band->threshold == 0.0f) {
                    sce->zeroes[(w+w2)*16+g] = 1;
                    continue;
                }
                sce->zeroes[(w+w2)*16+g] = 0;
                nz = 1;
                for (i = 0; i < sce->ics.swb_sizes[g]; i++) {
                    float t = fabsf(coefs[w2*128+i]);
                    if (t > 0.0f)
                        qmin = FFMIN(qmin, t);
                    qmax = FFMAX(qmax, t);
                }
            }
            if (nz) {
                int minscale, maxscale;
                float minrd = INFINITY;
                float maxval;
                //minimum scalefactor index is when minimum nonzero coefficient after quantizing is not clipped
                minscale = coef2minsf(qmin);
                //maximum scalefactor index is when maximum coefficient after quantizing is still not zero
                maxscale = coef2maxsf(qmax);
                minscale = av_clip(minscale - q0, 0, TRELLIS_STATES - 1);
                maxscale = av_clip(maxscale - q0, 0, TRELLIS_STATES);
                if (minscale == maxscale) {
                    maxscale = av_clip(minscale+1, 1, TRELLIS_STATES);
                    minscale = av_clip(maxscale-1, 0, TRELLIS_STATES - 1);
                }
                maxval = find_max_val(sce->ics.group_len[w], sce->ics.swb_sizes[g], s->scoefs+start);
                for (q = minscale; q < maxscale; q++) {
                    float dist = 0;
                    int cb = find_min_book(maxval, sce->sf_idx[w*16+g]);
                    for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) {
                        FFPsyBand *band = &s->psy.ch[s->cur_channel].psy_bands[(w+w2)*16+g];
                        dist += quantize_band_cost(s, coefs + w2*128, s->scoefs + start + w2*128, sce->ics.swb_sizes[g],
                                                   q + q0, cb, lambda / band->threshold, INFINITY, NULL, NULL, 0);
                    }
                    minrd = FFMIN(minrd, dist);

                    for (i = 0; i < q1 - q0; i++) {
                        float cost;
                        cost = paths[idx - 1][i].cost + dist
                               + ff_aac_scalefactor_bits[q - i + SCALE_DIFF_ZERO];
                        if (cost < paths[idx][q].cost) {
                            paths[idx][q].cost    = cost;
                            paths[idx][q].prev    = i;
                        }
                    }
                }
            } else {
                for (q = 0; q < q1 - q0; q++) {
                    paths[idx][q].cost = paths[idx - 1][q].cost + 1;
                    paths[idx][q].prev = q;
                }
            }
            sce->zeroes[w*16+g] = !nz;
            start += sce->ics.swb_sizes[g];
            idx++;
        }
    }
    idx--;
    mincost = paths[idx][0].cost;
    minq    = 0;
    for (i = 1; i < TRELLIS_STATES; i++) {
        if (paths[idx][i].cost < mincost) {
            mincost = paths[idx][i].cost;
            minq = i;
        }
    }
    while (idx) {
        sce->sf_idx[bandaddr[idx]] = minq + q0;
        minq = FFMAX(paths[idx][minq].prev, 0);
        idx--;
    }
    //set the same quantizers inside window groups
    for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w])
        for (g = 0;  g < sce->ics.num_swb; g++)
            for (w2 = 1; w2 < sce->ics.group_len[w]; w2++)
                sce->sf_idx[(w+w2)*16+g] = sce->sf_idx[w*16+g];
}

static void search_for_quantizers_fast(AVCodecContext *avctx, AACEncContext *s,
                                       SingleChannelElement *sce,
                                       const float lambda)
{
    int i, w, w2, g;
    int minq = 255;

    memset(sce->sf_idx, 0, sizeof(sce->sf_idx));
    for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {
        for (g = 0; g < sce->ics.num_swb; g++) {
            for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) {
                FFPsyBand *band = &s->psy.ch[s->cur_channel].psy_bands[(w+w2)*16+g];
                if (band->energy <= band->threshold) {
                    sce->sf_idx[(w+w2)*16+g] = 218;
                    sce->zeroes[(w+w2)*16+g] = 1;
                } else {
                    sce->sf_idx[(w+w2)*16+g] = av_clip(SCALE_ONE_POS - SCALE_DIV_512 + log2f(band->threshold), 80, 218);
                    sce->zeroes[(w+w2)*16+g] = 0;
                }
                minq = FFMIN(minq, sce->sf_idx[(w+w2)*16+g]);
            }
        }
    }
    for (i = 0; i < 128; i++) {
        sce->sf_idx[i] = 140;
        //av_clip(sce->sf_idx[i], minq, minq + SCALE_MAX_DIFF - 1);
    }
    //set the same quantizers inside window groups
    for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w])
        for (g = 0;  g < sce->ics.num_swb; g++)
            for (w2 = 1; w2 < sce->ics.group_len[w]; w2++)
                sce->sf_idx[(w+w2)*16+g] = sce->sf_idx[w*16+g];
}

static void search_for_pns(AACEncContext *s, AVCodecContext *avctx, SingleChannelElement *sce)
{
    FFPsyBand *band;
    int w, g, w2, i;
    int wlen = 1024 / sce->ics.num_windows;
    int bandwidth, cutoff;
    float *PNS = &s->scoefs[0*128], *PNS34 = &s->scoefs[1*128];
    float *NOR34 = &s->scoefs[3*128];
    uint8_t nextband[128];
    const float lambda = s->lambda;
    const float freq_mult = avctx->sample_rate*0.5f/wlen;
    const float thr_mult = NOISE_LAMBDA_REPLACE*(100.0f/lambda);
    const float spread_threshold = FFMIN(0.75f, NOISE_SPREAD_THRESHOLD*FFMAX(0.5f, lambda/100.f));
    const float dist_bias = av_clipf(4.f * 120 / lambda, 0.25f, 4.0f);
    const float pns_transient_energy_r = FFMIN(0.7f, lambda / 140.f);

    int refbits = avctx->bit_rate * 1024.0 / avctx->sample_rate
        / ((avctx->flags & CODEC_FLAG_QSCALE) ? 2.0f : avctx->channels)
        * (lambda / 120.f);

    /** Keep this in sync with twoloop's cutoff selection */
    float rate_bandwidth_multiplier = 1.5f;
    int prev = -1000, prev_sf = -1;
    int frame_bit_rate = (avctx->flags & CODEC_FLAG_QSCALE)
        ? (refbits * rate_bandwidth_multiplier * avctx->sample_rate / 1024)
        : (avctx->bit_rate / avctx->channels);

    frame_bit_rate *= 1.15f;

    if (avctx->cutoff > 0) {
        bandwidth = avctx->cutoff;
    } else {
        bandwidth = FFMAX(3000, AAC_CUTOFF_FROM_BITRATE(frame_bit_rate, 1, avctx->sample_rate));
    }

    cutoff = bandwidth * 2 * wlen / avctx->sample_rate;

    memcpy(sce->band_alt, sce->band_type, sizeof(sce->band_type));
    ff_init_nextband_map(sce, nextband);
    for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {
        int wstart = w*128;
        for (g = 0;  g < sce->ics.num_swb; g++) {
            int noise_sfi;
            float dist1 = 0.0f, dist2 = 0.0f, noise_amp;
            float pns_energy = 0.0f, pns_tgt_energy, energy_ratio, dist_thresh;
            float sfb_energy = 0.0f, threshold = 0.0f, spread = 2.0f;
            float min_energy = -1.0f, max_energy = 0.0f;
            const int start = wstart+sce->ics.swb_offset[g];
            const float freq = (start-wstart)*freq_mult;
            const float freq_boost = FFMAX(0.88f*freq/NOISE_LOW_LIMIT, 1.0f);
            if (freq < NOISE_LOW_LIMIT || (start-wstart) >= cutoff) {
                if (!sce->zeroes[w*16+g])
                    prev_sf = sce->sf_idx[w*16+g];
                continue;
            }
            for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) {
                band = &s->psy.ch[s->cur_channel].psy_bands[(w+w2)*16+g];
                sfb_energy += band->energy;
                spread     = FFMIN(spread, band->spread);
                threshold  += band->threshold;
                if (!w2) {
                    min_energy = max_energy = band->energy;
                } else {
                    min_energy = FFMIN(min_energy, band->energy);
                    max_energy = FFMAX(max_energy, band->energy);
                }
            }

            /* Ramps down at ~8000Hz and loosens the dist threshold */
            dist_thresh = av_clipf(2.5f*NOISE_LOW_LIMIT/freq, 0.5f, 2.5f) * dist_bias;

            /* PNS is acceptable when all of these are true:
             * 1. high spread energy (noise-like band)
             * 2. near-threshold energy (high PE means the random nature of PNS content will be noticed)
             * 3. on short window groups, all windows have similar energy (variations in energy would be destroyed by PNS)
             *
             * At this stage, point 2 is relaxed for zeroed bands near the noise threshold (hole avoidance is more important)
             */
            if ((!sce->zeroes[w*16+g] && !ff_sfdelta_can_remove_band(sce, nextband, prev_sf, w*16+g)) ||
                ((sce->zeroes[w*16+g] || !sce->band_alt[w*16+g]) && sfb_energy < threshold*sqrtf(1.0f/freq_boost)) || spread < spread_threshold ||
                (!sce->zeroes[w*16+g] && sce->band_alt[w*16+g] && sfb_energy > threshold*thr_mult*freq_boost) ||
                min_energy < pns_transient_energy_r * max_energy ) {
                sce->pns_ener[w*16+g] = sfb_energy;
                if (!sce->zeroes[w*16+g])
                    prev_sf = sce->sf_idx[w*16+g];
                continue;
            }

            pns_tgt_energy = sfb_energy*FFMIN(1.0f, spread*spread);
            noise_sfi = av_clip(roundf(log2f(pns_tgt_energy)*2), -100, 155); /* Quantize */
            noise_amp = -ff_aac_pow2sf_tab[noise_sfi + POW_SF2_ZERO];    /* Dequantize */
            if (prev != -1000) {
                int noise_sfdiff = noise_sfi - prev + SCALE_DIFF_ZERO;
                if (noise_sfdiff < 0 || noise_sfdiff > 2*SCALE_MAX_DIFF) {
                    if (!sce->zeroes[w*16+g])
                        prev_sf = sce->sf_idx[w*16+g];
                    continue;
                }
            }
            for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) {
                float band_energy, scale, pns_senergy;
                const int start_c = (w+w2)*128+sce->ics.swb_offset[g];
                band = &s->psy.ch[s->cur_channel].psy_bands[(w+w2)*16+g];
                for (i = 0; i < sce->ics.swb_sizes[g]; i+=2) {
                    double rnd[2];
                    av_bmg_get(&s->lfg, rnd);
                    PNS[i+0] = (float)rnd[0];
                    PNS[i+1] = (float)rnd[1];
                }
                band_energy = s->fdsp->scalarproduct_float(PNS, PNS, sce->ics.swb_sizes[g]);
                scale = noise_amp/sqrtf(band_energy);
                s->fdsp->vector_fmul_scalar(PNS, PNS, scale, sce->ics.swb_sizes[g]);
                pns_senergy = s->fdsp->scalarproduct_float(PNS, PNS, sce->ics.swb_sizes[g]);
                pns_energy += pns_senergy;
                abs_pow34_v(NOR34, &sce->coeffs[start_c], sce->ics.swb_sizes[g]);
                abs_pow34_v(PNS34, PNS, sce->ics.swb_sizes[g]);
                dist1 += quantize_band_cost(s, &sce->coeffs[start_c],
                                            NOR34,
                                            sce->ics.swb_sizes[g],
                                            sce->sf_idx[(w+w2)*16+g],
                                            sce->band_alt[(w+w2)*16+g],
                                            lambda/band->threshold, INFINITY, NULL, NULL, 0);
                /* Estimate rd on average as 5 bits for SF, 4 for the CB, plus spread energy * lambda/thr */
                dist2 += band->energy/(band->spread*band->spread)*lambda*dist_thresh/band->threshold;
            }
            if (g && sce->band_type[w*16+g-1] == NOISE_BT) {
                dist2 += 5;
            } else {
                dist2 += 9;
            }
            energy_ratio = pns_tgt_energy/pns_energy; /* Compensates for quantization error */
            sce->pns_ener[w*16+g] = energy_ratio*pns_tgt_energy;
            if (sce->zeroes[w*16+g] || !sce->band_alt[w*16+g] || (energy_ratio > 0.85f && energy_ratio < 1.25f && dist2 < dist1)) {
                sce->band_type[w*16+g] = NOISE_BT;
                sce->zeroes[w*16+g] = 0;
                prev = noise_sfi;
            } else {
                if (!sce->zeroes[w*16+g])
                    prev_sf = sce->sf_idx[w*16+g];
            }
        }
    }
}

static void mark_pns(AACEncContext *s, AVCodecContext *avctx, SingleChannelElement *sce)
{
    FFPsyBand *band;
    int w, g, w2;
    int wlen = 1024 / sce->ics.num_windows;
    int bandwidth, cutoff;
    const float lambda = s->lambda;
    const float freq_mult = avctx->sample_rate*0.5f/wlen;
    const float spread_threshold = FFMIN(0.75f, NOISE_SPREAD_THRESHOLD*FFMAX(0.5f, lambda/100.f));
    const float pns_transient_energy_r = FFMIN(0.7f, lambda / 140.f);

    int refbits = avctx->bit_rate * 1024.0 / avctx->sample_rate
        / ((avctx->flags & CODEC_FLAG_QSCALE) ? 2.0f : avctx->channels)
        * (lambda / 120.f);

    /** Keep this in sync with twoloop's cutoff selection */
    float rate_bandwidth_multiplier = 1.5f;
    int frame_bit_rate = (avctx->flags & CODEC_FLAG_QSCALE)
        ? (refbits * rate_bandwidth_multiplier * avctx->sample_rate / 1024)
        : (avctx->bit_rate / avctx->channels);

    frame_bit_rate *= 1.15f;

    if (avctx->cutoff > 0) {
        bandwidth = avctx->cutoff;
    } else {
        bandwidth = FFMAX(3000, AAC_CUTOFF_FROM_BITRATE(frame_bit_rate, 1, avctx->sample_rate));
    }

    cutoff = bandwidth * 2 * wlen / avctx->sample_rate;

    memcpy(sce->band_alt, sce->band_type, sizeof(sce->band_type));
    for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {
        for (g = 0;  g < sce->ics.num_swb; g++) {
            float sfb_energy = 0.0f, threshold = 0.0f, spread = 2.0f;
            float min_energy = -1.0f, max_energy = 0.0f;
            const int start = sce->ics.swb_offset[g];
            const float freq = start*freq_mult;
            const float freq_boost = FFMAX(0.88f*freq/NOISE_LOW_LIMIT, 1.0f);
            if (freq < NOISE_LOW_LIMIT || start >= cutoff) {
                sce->can_pns[w*16+g] = 0;
                continue;
            }
            for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) {
                band = &s->psy.ch[s->cur_channel].psy_bands[(w+w2)*16+g];
                sfb_energy += band->energy;
                spread     = FFMIN(spread, band->spread);
                threshold  += band->threshold;
                if (!w2) {
                    min_energy = max_energy = band->energy;
                } else {
                    min_energy = FFMIN(min_energy, band->energy);
                    max_energy = FFMAX(max_energy, band->energy);
                }
            }

            /* PNS is acceptable when all of these are true:
             * 1. high spread energy (noise-like band)
             * 2. near-threshold energy (high PE means the random nature of PNS content will be noticed)
             * 3. on short window groups, all windows have similar energy (variations in energy would be destroyed by PNS)
             */
            sce->pns_ener[w*16+g] = sfb_energy;
            if (sfb_energy < threshold*sqrtf(1.5f/freq_boost) || spread < spread_threshold || min_energy < pns_transient_energy_r * max_energy) {
                sce->can_pns[w*16+g] = 0;
            } else {
                sce->can_pns[w*16+g] = 1;
            }
        }
    }
}

static void search_for_ms(AACEncContext *s, ChannelElement *cpe)
{
    int start = 0, i, w, w2, g, sid_sf_boost, prev_mid, prev_side;
    uint8_t nextband0[128], nextband1[128];
    float M[128], S[128];
    float *L34 = s->scoefs, *R34 = s->scoefs + 128, *M34 = s->scoefs + 128*2, *S34 = s->scoefs + 128*3;
    const float lambda = s->lambda;
    const float mslambda = FFMIN(1.0f, lambda / 120.f);
    SingleChannelElement *sce0 = &cpe->ch[0];
    SingleChannelElement *sce1 = &cpe->ch[1];
    if (!cpe->common_window)
        return;

    /** Scout out next nonzero bands */
    ff_init_nextband_map(sce0, nextband0);
    ff_init_nextband_map(sce1, nextband1);

    prev_mid = sce0->sf_idx[0];
    prev_side = sce1->sf_idx[0];
    for (w = 0; w < sce0->ics.num_windows; w += sce0->ics.group_len[w]) {
        start = 0;
        for (g = 0;  g < sce0->ics.num_swb; g++) {
            float bmax = bval2bmax(g * 17.0f / sce0->ics.num_swb) / 0.0045f;
            if (!cpe->is_mask[w*16+g])
                cpe->ms_mask[w*16+g] = 0;
            if (!sce0->zeroes[w*16+g] && !sce1->zeroes[w*16+g] && !cpe->is_mask[w*16+g]) {
                float Mmax = 0.0f, Smax = 0.0f;

                /* Must compute mid/side SF and book for the whole window group */
                for (w2 = 0; w2 < sce0->ics.group_len[w]; w2++) {
                    for (i = 0; i < sce0->ics.swb_sizes[g]; i++) {
                        M[i] = (sce0->coeffs[start+(w+w2)*128+i]
                              + sce1->coeffs[start+(w+w2)*128+i]) * 0.5;
                        S[i] =  M[i]
                              - sce1->coeffs[start+(w+w2)*128+i];
                    }
                    abs_pow34_v(M34, M, sce0->ics.swb_sizes[g]);
                    abs_pow34_v(S34, S, sce0->ics.swb_sizes[g]);
                    for (i = 0; i < sce0->ics.swb_sizes[g]; i++ ) {
                        Mmax = FFMAX(Mmax, M34[i]);
                        Smax = FFMAX(Smax, S34[i]);
                    }
                }

                for (sid_sf_boost = 0; sid_sf_boost < 4; sid_sf_boost++) {
                    float dist1 = 0.0f, dist2 = 0.0f;
                    int B0 = 0, B1 = 0;
                    int minidx;
                    int mididx, sididx;
                    int midcb, sidcb;

                    minidx = FFMIN(sce0->sf_idx[w*16+g], sce1->sf_idx[w*16+g]);
                    mididx = av_clip(minidx, 0, SCALE_MAX_POS - SCALE_DIV_512);
                    sididx = av_clip(minidx - sid_sf_boost * 3, 0, SCALE_MAX_POS - SCALE_DIV_512);
                    if (sce0->band_type[w*16+g] != NOISE_BT && sce1->band_type[w*16+g] != NOISE_BT
                        && (   !ff_sfdelta_can_replace(sce0, nextband0, prev_mid, mididx, w*16+g)
                            || !ff_sfdelta_can_replace(sce1, nextband1, prev_side, sididx, w*16+g))) {
                        /* scalefactor range violation, bad stuff, will decrease quality unacceptably */
                        continue;
                    }

                    midcb = find_min_book(Mmax, mididx);
                    sidcb = find_min_book(Smax, sididx);

                    /* No CB can be zero */
                    midcb = FFMAX(1,midcb);
                    sidcb = FFMAX(1,sidcb);

                    for (w2 = 0; w2 < sce0->ics.group_len[w]; w2++) {
                        FFPsyBand *band0 = &s->psy.ch[s->cur_channel+0].psy_bands[(w+w2)*16+g];
                        FFPsyBand *band1 = &s->psy.ch[s->cur_channel+1].psy_bands[(w+w2)*16+g];
                        float minthr = FFMIN(band0->threshold, band1->threshold);
                        int b1,b2,b3,b4;
                        for (i = 0; i < sce0->ics.swb_sizes[g]; i++) {
                            M[i] = (sce0->coeffs[start+(w+w2)*128+i]
                                  + sce1->coeffs[start+(w+w2)*128+i]) * 0.5;
                            S[i] =  M[i]
                                  - sce1->coeffs[start+(w+w2)*128+i];
                        }

                        abs_pow34_v(L34, sce0->coeffs+start+(w+w2)*128, sce0->ics.swb_sizes[g]);
                        abs_pow34_v(R34, sce1->coeffs+start+(w+w2)*128, sce0->ics.swb_sizes[g]);
                        abs_pow34_v(M34, M,                         sce0->ics.swb_sizes[g]);
                        abs_pow34_v(S34, S,                         sce0->ics.swb_sizes[g]);
                        dist1 += quantize_band_cost(s, &sce0->coeffs[start + (w+w2)*128],
                                                    L34,
                                                    sce0->ics.swb_sizes[g],
                                                    sce0->sf_idx[w*16+g],
                                                    sce0->band_type[w*16+g],
                                                    lambda / band0->threshold, INFINITY, &b1, NULL, 0);
                        dist1 += quantize_band_cost(s, &sce1->coeffs[start + (w+w2)*128],
                                                    R34,
                                                    sce1->ics.swb_sizes[g],
                                                    sce1->sf_idx[w*16+g],
                                                    sce1->band_type[w*16+g],
                                                    lambda / band1->threshold, INFINITY, &b2, NULL, 0);
                        dist2 += quantize_band_cost(s, M,
                                                    M34,
                                                    sce0->ics.swb_sizes[g],
                                                    mididx,
                                                    midcb,
                                                    lambda / minthr, INFINITY, &b3, NULL, 0);
                        dist2 += quantize_band_cost(s, S,
                                                    S34,
                                                    sce1->ics.swb_sizes[g],
                                                    sididx,
                                                    sidcb,
                                                    mslambda / (minthr * bmax), INFINITY, &b4, NULL, 0);
                        B0 += b1+b2;
                        B1 += b3+b4;
                        dist1 -= b1+b2;
                        dist2 -= b3+b4;
                    }
                    cpe->ms_mask[w*16+g] = dist2 <= dist1 && B1 < B0;
                    if (cpe->ms_mask[w*16+g]) {
                        if (sce0->band_type[w*16+g] != NOISE_BT && sce1->band_type[w*16+g] != NOISE_BT) {
                            sce0->sf_idx[w*16+g] = mididx;
                            sce1->sf_idx[w*16+g] = sididx;
                            sce0->band_type[w*16+g] = midcb;
                            sce1->band_type[w*16+g] = sidcb;
                        } else if ((sce0->band_type[w*16+g] != NOISE_BT) ^ (sce1->band_type[w*16+g] != NOISE_BT)) {
                            /* ms_mask unneeded, and it confuses some decoders */
                            cpe->ms_mask[w*16+g] = 0;
                        }
                        break;
                    } else if (B1 > B0) {
                        /* More boost won't fix this */
                        break;
                    }
                }
            }
            if (!sce0->zeroes[w*16+g] && sce0->band_type[w*16+g] < RESERVED_BT)
                prev_mid = sce0->sf_idx[w*16+g];
            if (!sce1->zeroes[w*16+g] && !cpe->is_mask[w*16+g] && sce1->band_type[w*16+g] < RESERVED_BT)
                prev_side = sce1->sf_idx[w*16+g];
            start += sce0->ics.swb_sizes[g];
        }
    }
}

AACCoefficientsEncoder ff_aac_coders[AAC_CODER_NB] = {
    [AAC_CODER_ANMR] = {
        search_for_quantizers_anmr,
        encode_window_bands_info,
        quantize_and_encode_band,
        ff_aac_encode_tns_info,
        ff_aac_encode_ltp_info,
        ff_aac_encode_main_pred,
        ff_aac_adjust_common_pred,
        ff_aac_adjust_common_ltp,
        ff_aac_apply_main_pred,
        ff_aac_apply_tns,
        ff_aac_update_ltp,
        ff_aac_ltp_insert_new_frame,
        set_special_band_scalefactors,
        search_for_pns,
        mark_pns,
        ff_aac_search_for_tns,
        ff_aac_search_for_ltp,
        search_for_ms,
        ff_aac_search_for_is,
        ff_aac_search_for_pred,
    },
    [AAC_CODER_TWOLOOP] = {
        search_for_quantizers_twoloop,
        codebook_trellis_rate,
        quantize_and_encode_band,
        ff_aac_encode_tns_info,
        ff_aac_encode_ltp_info,
        ff_aac_encode_main_pred,
        ff_aac_adjust_common_pred,
        ff_aac_adjust_common_ltp,
        ff_aac_apply_main_pred,
        ff_aac_apply_tns,
        ff_aac_update_ltp,
        ff_aac_ltp_insert_new_frame,
        set_special_band_scalefactors,
        search_for_pns,
        mark_pns,
        ff_aac_search_for_tns,
        ff_aac_search_for_ltp,
        search_for_ms,
        ff_aac_search_for_is,
        ff_aac_search_for_pred,
    },
    [AAC_CODER_FAST] = {
        search_for_quantizers_fast,
        encode_window_bands_info,
        quantize_and_encode_band,
        ff_aac_encode_tns_info,
        ff_aac_encode_ltp_info,
        ff_aac_encode_main_pred,
        ff_aac_adjust_common_pred,
        ff_aac_adjust_common_ltp,
        ff_aac_apply_main_pred,
        ff_aac_apply_tns,
        ff_aac_update_ltp,
        ff_aac_ltp_insert_new_frame,
        set_special_band_scalefactors,
        search_for_pns,
        mark_pns,
        ff_aac_search_for_tns,
        ff_aac_search_for_ltp,
        search_for_ms,
        ff_aac_search_for_is,
        ff_aac_search_for_pred,
    },
};