aboutsummaryrefslogtreecommitdiffstats
path: root/libavfilter/vf_dctdnoiz.c
blob: a9017b1f1c822a0794f82dbbdcbd9760b4badd8d (plain) (blame)
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
/*
 * Copyright (c) 2013-2014 Clément Bœsch
 *
 * 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
 */

/**
 * A simple, relatively efficient and slow DCT image denoiser.
 *
 * @see http://www.ipol.im/pub/art/2011/ys-dct/
 *
 * The DCT factorization used is based on "Fast and numerically stable
 * algorithms for discrete cosine transforms" from Gerlind Plonkaa & Manfred
 * Tasche (DOI: 10.1016/j.laa.2004.07.015).
 */

#include "libavutil/avassert.h"
#include "libavutil/eval.h"
#include "libavutil/opt.h"
#include "internal.h"

static const char *const var_names[] = { "c", NULL };
enum { VAR_C, VAR_VARS_NB };

#define MAX_THREADS 8

typedef struct DCTdnoizContext {
    const AVClass *class;

    /* coefficient factor expression */
    char *expr_str;
    AVExpr *expr[MAX_THREADS];
    double var_values[MAX_THREADS][VAR_VARS_NB];

    int nb_threads;
    int pr_width, pr_height;    // width and height to process
    float sigma;                // used when no expression are st
    float th;                   // threshold (3*sigma)
    float *cbuf[2][3];          // two planar rgb color buffers
    float *slices[MAX_THREADS]; // slices buffers (1 slice buffer per thread)
    float *weights;             // dct coeff are cumulated with overlapping; these values are used for averaging
    int p_linesize;             // line sizes for color and weights
    int overlap;                // number of block overlapping pixels
    int step;                   // block step increment (blocksize - overlap)
    int n;                      // 1<<n is the block size
    int bsize;                  // block size, 1<<n
    void (*filter_freq_func)(struct DCTdnoizContext *s,
                             const float *src, int src_linesize,
                             float *dst, int dst_linesize,
                             int thread_id);
    void (*color_decorrelation)(float **dst, int dst_linesize,
                                const uint8_t *src, int src_linesize,
                                int w, int h);
    void (*color_correlation)(uint8_t *dst, int dst_linesize,
                              float **src, int src_linesize,
                              int w, int h);
} DCTdnoizContext;

#define MIN_NBITS 3 /* blocksize = 1<<3 =  8 */
#define MAX_NBITS 4 /* blocksize = 1<<4 = 16 */
#define DEFAULT_NBITS 3

#define OFFSET(x) offsetof(DCTdnoizContext, x)
#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
static const AVOption dctdnoiz_options[] = {
    { "sigma",   "set noise sigma constant",               OFFSET(sigma),    AV_OPT_TYPE_FLOAT,  {.dbl=0},            0, 999,          .flags = FLAGS },
    { "s",       "set noise sigma constant",               OFFSET(sigma),    AV_OPT_TYPE_FLOAT,  {.dbl=0},            0, 999,          .flags = FLAGS },
    { "overlap", "set number of block overlapping pixels", OFFSET(overlap),  AV_OPT_TYPE_INT,    {.i64=-1}, -1, (1<<MAX_NBITS)-1, .flags = FLAGS },
    { "expr",    "set coefficient factor expression",      OFFSET(expr_str), AV_OPT_TYPE_STRING, {.str=NULL},                          .flags = FLAGS },
    { "e",       "set coefficient factor expression",      OFFSET(expr_str), AV_OPT_TYPE_STRING, {.str=NULL},                          .flags = FLAGS },
    { "n",       "set the block size, expressed in bits",  OFFSET(n),        AV_OPT_TYPE_INT,    {.i64=DEFAULT_NBITS}, MIN_NBITS, MAX_NBITS, .flags = FLAGS },
    { NULL }
};

AVFILTER_DEFINE_CLASS(dctdnoiz);

static void av_always_inline fdct8_1d(float *dst, const float *src,
                                      int dst_stridea, int dst_strideb,
                                      int src_stridea, int src_strideb)
{
    int i;

    for (i = 0; i < 8; i++) {
        const float x00 = src[0*src_stridea] + src[7*src_stridea];
        const float x01 = src[1*src_stridea] + src[6*src_stridea];
        const float x02 = src[2*src_stridea] + src[5*src_stridea];
        const float x03 = src[3*src_stridea] + src[4*src_stridea];
        const float x04 = src[0*src_stridea] - src[7*src_stridea];
        const float x05 = src[1*src_stridea] - src[6*src_stridea];
        const float x06 = src[2*src_stridea] - src[5*src_stridea];
        const float x07 = src[3*src_stridea] - src[4*src_stridea];
        const float x08 = x00 + x03;
        const float x09 = x01 + x02;
        const float x0a = x00 - x03;
        const float x0b = x01 - x02;
        const float x0c = 1.38703984532215f*x04 + 0.275899379282943f*x07;
        const float x0d = 1.17587560241936f*x05 + 0.785694958387102f*x06;
        const float x0e = -0.785694958387102f*x05 + 1.17587560241936f*x06;
        const float x0f = 0.275899379282943f*x04 - 1.38703984532215f*x07;
        const float x10 = 0.353553390593274f * (x0c - x0d);
        const float x11 = 0.353553390593274f * (x0e - x0f);
        dst[0*dst_stridea] = 0.353553390593274f * (x08 + x09);
        dst[1*dst_stridea] = 0.353553390593274f * (x0c + x0d);
        dst[2*dst_stridea] = 0.461939766255643f*x0a + 0.191341716182545f*x0b;
        dst[3*dst_stridea] = 0.707106781186547f * (x10 - x11);
        dst[4*dst_stridea] = 0.353553390593274f * (x08 - x09);
        dst[5*dst_stridea] = 0.707106781186547f * (x10 + x11);
        dst[6*dst_stridea] = 0.191341716182545f*x0a - 0.461939766255643f*x0b;
        dst[7*dst_stridea] = 0.353553390593274f * (x0e + x0f);
        dst += dst_strideb;
        src += src_strideb;
    }
}

static void av_always_inline idct8_1d(float *dst, const float *src,
                                      int dst_stridea, int dst_strideb,
                                      int src_stridea, int src_strideb,
                                      int add)
{
    int i;

    for (i = 0; i < 8; i++) {
        const float x00 =  1.4142135623731f  *src[0*src_stridea];
        const float x01 =  1.38703984532215f *src[1*src_stridea] + 0.275899379282943f*src[7*src_stridea];
        const float x02 =  1.30656296487638f *src[2*src_stridea] + 0.541196100146197f*src[6*src_stridea];
        const float x03 =  1.17587560241936f *src[3*src_stridea] + 0.785694958387102f*src[5*src_stridea];
        const float x04 =  1.4142135623731f  *src[4*src_stridea];
        const float x05 = -0.785694958387102f*src[3*src_stridea] + 1.17587560241936f*src[5*src_stridea];
        const float x06 =  0.541196100146197f*src[2*src_stridea] - 1.30656296487638f*src[6*src_stridea];
        const float x07 = -0.275899379282943f*src[1*src_stridea] + 1.38703984532215f*src[7*src_stridea];
        const float x09 = x00 + x04;
        const float x0a = x01 + x03;
        const float x0b = 1.4142135623731f*x02;
        const float x0c = x00 - x04;
        const float x0d = x01 - x03;
        const float x0e = 0.353553390593274f * (x09 - x0b);
        const float x0f = 0.353553390593274f * (x0c + x0d);
        const float x10 = 0.353553390593274f * (x0c - x0d);
        const float x11 = 1.4142135623731f*x06;
        const float x12 = x05 + x07;
        const float x13 = x05 - x07;
        const float x14 = 0.353553390593274f * (x11 + x12);
        const float x15 = 0.353553390593274f * (x11 - x12);
        const float x16 = 0.5f*x13;
        dst[0*dst_stridea] = (add ? dst[ 0*dst_stridea] : 0) + 0.25f * (x09 + x0b) + 0.353553390593274f*x0a;
        dst[1*dst_stridea] = (add ? dst[ 1*dst_stridea] : 0) + 0.707106781186547f * (x0f + x15);
        dst[2*dst_stridea] = (add ? dst[ 2*dst_stridea] : 0) + 0.707106781186547f * (x0f - x15);
        dst[3*dst_stridea] = (add ? dst[ 3*dst_stridea] : 0) + 0.707106781186547f * (x0e + x16);
        dst[4*dst_stridea] = (add ? dst[ 4*dst_stridea] : 0) + 0.707106781186547f * (x0e - x16);
        dst[5*dst_stridea] = (add ? dst[ 5*dst_stridea] : 0) + 0.707106781186547f * (x10 - x14);
        dst[6*dst_stridea] = (add ? dst[ 6*dst_stridea] : 0) + 0.707106781186547f * (x10 + x14);
        dst[7*dst_stridea] = (add ? dst[ 7*dst_stridea] : 0) + 0.25f * (x09 + x0b) - 0.353553390593274f*x0a;
        dst += dst_strideb;
        src += src_strideb;
    }
}


static void av_always_inline fdct16_1d(float *dst, const float *src,
                                       int dst_stridea, int dst_strideb,
                                       int src_stridea, int src_strideb)
{
    int i;

    for (i = 0; i < 16; i++) {
        const float x00 = src[ 0*src_stridea] + src[15*src_stridea];
        const float x01 = src[ 1*src_stridea] + src[14*src_stridea];
        const float x02 = src[ 2*src_stridea] + src[13*src_stridea];
        const float x03 = src[ 3*src_stridea] + src[12*src_stridea];
        const float x04 = src[ 4*src_stridea] + src[11*src_stridea];
        const float x05 = src[ 5*src_stridea] + src[10*src_stridea];
        const float x06 = src[ 6*src_stridea] + src[ 9*src_stridea];
        const float x07 = src[ 7*src_stridea] + src[ 8*src_stridea];
        const float x08 = src[ 0*src_stridea] - src[15*src_stridea];
        const float x09 = src[ 1*src_stridea] - src[14*src_stridea];
        const float x0a = src[ 2*src_stridea] - src[13*src_stridea];
        const float x0b = src[ 3*src_stridea] - src[12*src_stridea];
        const float x0c = src[ 4*src_stridea] - src[11*src_stridea];
        const float x0d = src[ 5*src_stridea] - src[10*src_stridea];
        const float x0e = src[ 6*src_stridea] - src[ 9*src_stridea];
        const float x0f = src[ 7*src_stridea] - src[ 8*src_stridea];
        const float x10 = x00 + x07;
        const float x11 = x01 + x06;
        const float x12 = x02 + x05;
        const float x13 = x03 + x04;
        const float x14 = x00 - x07;
        const float x15 = x01 - x06;
        const float x16 = x02 - x05;
        const float x17 = x03 - x04;
        const float x18 = x10 + x13;
        const float x19 = x11 + x12;
        const float x1a = x10 - x13;
        const float x1b = x11 - x12;
        const float x1c =   1.38703984532215f*x14 + 0.275899379282943f*x17;
        const float x1d =   1.17587560241936f*x15 + 0.785694958387102f*x16;
        const float x1e = -0.785694958387102f*x15 + 1.17587560241936f *x16;
        const float x1f =  0.275899379282943f*x14 - 1.38703984532215f *x17;
        const float x20 = 0.25f * (x1c - x1d);
        const float x21 = 0.25f * (x1e - x1f);
        const float x22 =  1.40740373752638f *x08 + 0.138617169199091f*x0f;
        const float x23 =  1.35331800117435f *x09 + 0.410524527522357f*x0e;
        const float x24 =  1.24722501298667f *x0a + 0.666655658477747f*x0d;
        const float x25 =  1.09320186700176f *x0b + 0.897167586342636f*x0c;
        const float x26 = -0.897167586342636f*x0b + 1.09320186700176f *x0c;
        const float x27 =  0.666655658477747f*x0a - 1.24722501298667f *x0d;
        const float x28 = -0.410524527522357f*x09 + 1.35331800117435f *x0e;
        const float x29 =  0.138617169199091f*x08 - 1.40740373752638f *x0f;
        const float x2a = x22 + x25;
        const float x2b = x23 + x24;
        const float x2c = x22 - x25;
        const float x2d = x23 - x24;
        const float x2e = 0.25f * (x2a - x2b);
        const float x2f = 0.326640741219094f*x2c + 0.135299025036549f*x2d;
        const float x30 = 0.135299025036549f*x2c - 0.326640741219094f*x2d;
        const float x31 = x26 + x29;
        const float x32 = x27 + x28;
        const float x33 = x26 - x29;
        const float x34 = x27 - x28;
        const float x35 = 0.25f * (x31 - x32);
        const float x36 = 0.326640741219094f*x33 + 0.135299025036549f*x34;
        const float x37 = 0.135299025036549f*x33 - 0.326640741219094f*x34;
        dst[ 0*dst_stridea] = 0.25f * (x18 + x19);
        dst[ 1*dst_stridea] = 0.25f * (x2a + x2b);
        dst[ 2*dst_stridea] = 0.25f * (x1c + x1d);
        dst[ 3*dst_stridea] = 0.707106781186547f * (x2f - x37);
        dst[ 4*dst_stridea] = 0.326640741219094f*x1a + 0.135299025036549f*x1b;
        dst[ 5*dst_stridea] = 0.707106781186547f * (x2f + x37);
        dst[ 6*dst_stridea] = 0.707106781186547f * (x20 - x21);
        dst[ 7*dst_stridea] = 0.707106781186547f * (x2e + x35);
        dst[ 8*dst_stridea] = 0.25f * (x18 - x19);
        dst[ 9*dst_stridea] = 0.707106781186547f * (x2e - x35);
        dst[10*dst_stridea] = 0.707106781186547f * (x20 + x21);
        dst[11*dst_stridea] = 0.707106781186547f * (x30 - x36);
        dst[12*dst_stridea] = 0.135299025036549f*x1a - 0.326640741219094f*x1b;
        dst[13*dst_stridea] = 0.707106781186547f * (x30 + x36);
        dst[14*dst_stridea] = 0.25f * (x1e + x1f);
        dst[15*dst_stridea] = 0.25f * (x31 + x32);
        dst += dst_strideb;
        src += src_strideb;
    }
}

static void av_always_inline idct16_1d(float *dst, const float *src,
                                       int dst_stridea, int dst_strideb,
                                       int src_stridea, int src_strideb,
                                       int add)
{
    int i;

    for (i = 0; i < 16; i++) {
        const float x00 =  1.4142135623731f  *src[ 0*src_stridea];
        const float x01 =  1.40740373752638f *src[ 1*src_stridea] + 0.138617169199091f*src[15*src_stridea];
        const float x02 =  1.38703984532215f *src[ 2*src_stridea] + 0.275899379282943f*src[14*src_stridea];
        const float x03 =  1.35331800117435f *src[ 3*src_stridea] + 0.410524527522357f*src[13*src_stridea];
        const float x04 =  1.30656296487638f *src[ 4*src_stridea] + 0.541196100146197f*src[12*src_stridea];
        const float x05 =  1.24722501298667f *src[ 5*src_stridea] + 0.666655658477747f*src[11*src_stridea];
        const float x06 =  1.17587560241936f *src[ 6*src_stridea] + 0.785694958387102f*src[10*src_stridea];
        const float x07 =  1.09320186700176f *src[ 7*src_stridea] + 0.897167586342636f*src[ 9*src_stridea];
        const float x08 =  1.4142135623731f  *src[ 8*src_stridea];
        const float x09 = -0.897167586342636f*src[ 7*src_stridea] + 1.09320186700176f*src[ 9*src_stridea];
        const float x0a =  0.785694958387102f*src[ 6*src_stridea] - 1.17587560241936f*src[10*src_stridea];
        const float x0b = -0.666655658477747f*src[ 5*src_stridea] + 1.24722501298667f*src[11*src_stridea];
        const float x0c =  0.541196100146197f*src[ 4*src_stridea] - 1.30656296487638f*src[12*src_stridea];
        const float x0d = -0.410524527522357f*src[ 3*src_stridea] + 1.35331800117435f*src[13*src_stridea];
        const float x0e =  0.275899379282943f*src[ 2*src_stridea] - 1.38703984532215f*src[14*src_stridea];
        const float x0f = -0.138617169199091f*src[ 1*src_stridea] + 1.40740373752638f*src[15*src_stridea];
        const float x12 = x00 + x08;
        const float x13 = x01 + x07;
        const float x14 = x02 + x06;
        const float x15 = x03 + x05;
        const float x16 = 1.4142135623731f*x04;
        const float x17 = x00 - x08;
        const float x18 = x01 - x07;
        const float x19 = x02 - x06;
        const float x1a = x03 - x05;
        const float x1d = x12 + x16;
        const float x1e = x13 + x15;
        const float x1f = 1.4142135623731f*x14;
        const float x20 = x12 - x16;
        const float x21 = x13 - x15;
        const float x22 = 0.25f * (x1d - x1f);
        const float x23 = 0.25f * (x20 + x21);
        const float x24 = 0.25f * (x20 - x21);
        const float x25 = 1.4142135623731f*x17;
        const float x26 = 1.30656296487638f*x18 + 0.541196100146197f*x1a;
        const float x27 = 1.4142135623731f*x19;
        const float x28 = -0.541196100146197f*x18 + 1.30656296487638f*x1a;
        const float x29 = 0.176776695296637f * (x25 + x27) + 0.25f*x26;
        const float x2a = 0.25f * (x25 - x27);
        const float x2b = 0.176776695296637f * (x25 + x27) - 0.25f*x26;
        const float x2c = 0.353553390593274f*x28;
        const float x1b = 0.707106781186547f * (x2a - x2c);
        const float x1c = 0.707106781186547f * (x2a + x2c);
        const float x2d = 1.4142135623731f*x0c;
        const float x2e = x0b + x0d;
        const float x2f = x0a + x0e;
        const float x30 = x09 + x0f;
        const float x31 = x09 - x0f;
        const float x32 = x0a - x0e;
        const float x33 = x0b - x0d;
        const float x37 = 1.4142135623731f*x2d;
        const float x38 = 1.30656296487638f*x2e + 0.541196100146197f*x30;
        const float x39 = 1.4142135623731f*x2f;
        const float x3a = -0.541196100146197f*x2e + 1.30656296487638f*x30;
        const float x3b = 0.176776695296637f * (x37 + x39) + 0.25f*x38;
        const float x3c = 0.25f * (x37 - x39);
        const float x3d = 0.176776695296637f * (x37 + x39) - 0.25f*x38;
        const float x3e = 0.353553390593274f*x3a;
        const float x34 = 0.707106781186547f * (x3c - x3e);
        const float x35 = 0.707106781186547f * (x3c + x3e);
        const float x3f = 1.4142135623731f*x32;
        const float x40 = x31 + x33;
        const float x41 = x31 - x33;
        const float x42 = 0.25f * (x3f + x40);
        const float x43 = 0.25f * (x3f - x40);
        const float x44 = 0.353553390593274f*x41;
        dst[ 0*dst_stridea] = (add ? dst[ 0*dst_stridea] : 0) + 0.176776695296637f * (x1d + x1f) + 0.25f*x1e;
        dst[ 1*dst_stridea] = (add ? dst[ 1*dst_stridea] : 0) + 0.707106781186547f * (x29 + x3d);
        dst[ 2*dst_stridea] = (add ? dst[ 2*dst_stridea] : 0) + 0.707106781186547f * (x29 - x3d);
        dst[ 3*dst_stridea] = (add ? dst[ 3*dst_stridea] : 0) + 0.707106781186547f * (x23 - x43);
        dst[ 4*dst_stridea] = (add ? dst[ 4*dst_stridea] : 0) + 0.707106781186547f * (x23 + x43);
        dst[ 5*dst_stridea] = (add ? dst[ 5*dst_stridea] : 0) + 0.707106781186547f * (x1b - x35);
        dst[ 6*dst_stridea] = (add ? dst[ 6*dst_stridea] : 0) + 0.707106781186547f * (x1b + x35);
        dst[ 7*dst_stridea] = (add ? dst[ 7*dst_stridea] : 0) + 0.707106781186547f * (x22 + x44);
        dst[ 8*dst_stridea] = (add ? dst[ 8*dst_stridea] : 0) + 0.707106781186547f * (x22 - x44);
        dst[ 9*dst_stridea] = (add ? dst[ 9*dst_stridea] : 0) + 0.707106781186547f * (x1c + x34);
        dst[10*dst_stridea] = (add ? dst[10*dst_stridea] : 0) + 0.707106781186547f * (x1c - x34);
        dst[11*dst_stridea] = (add ? dst[11*dst_stridea] : 0) + 0.707106781186547f * (x24 + x42);
        dst[12*dst_stridea] = (add ? dst[12*dst_stridea] : 0) + 0.707106781186547f * (x24 - x42);
        dst[13*dst_stridea] = (add ? dst[13*dst_stridea] : 0) + 0.707106781186547f * (x2b - x3b);
        dst[14*dst_stridea] = (add ? dst[14*dst_stridea] : 0) + 0.707106781186547f * (x2b + x3b);
        dst[15*dst_stridea] = (add ? dst[15*dst_stridea] : 0) + 0.176776695296637f * (x1d + x1f) - 0.25f*x1e;
        dst += dst_strideb;
        src += src_strideb;
    }
}

#define DEF_FILTER_FREQ_FUNCS(bsize)                                                        \
static av_always_inline void filter_freq_##bsize(const float *src, int src_linesize,        \
                                                 float *dst, int dst_linesize,              \
                                                 AVExpr *expr, double *var_values,          \
                                                 int sigma_th)                              \
{                                                                                           \
    unsigned i;                                                                             \
    DECLARE_ALIGNED(32, float, tmp_block1)[bsize * bsize];                                  \
    DECLARE_ALIGNED(32, float, tmp_block2)[bsize * bsize];                                  \
                                                                                            \
    /* forward DCT */                                                                       \
    fdct##bsize##_1d(tmp_block1, src, 1, bsize, 1, src_linesize);                           \
    fdct##bsize##_1d(tmp_block2, tmp_block1, bsize, 1, bsize, 1);                           \
                                                                                            \
    for (i = 0; i < bsize*bsize; i++) {                                                     \
        float *b = &tmp_block2[i];                                                          \
        /* frequency filtering */                                                           \
        if (expr) {                                                                         \
            var_values[VAR_C] = FFABS(*b);                                                  \
            *b *= av_expr_eval(expr, var_values, NULL);                                     \
        } else {                                                                            \
            if (FFABS(*b) < sigma_th)                                                       \
                *b = 0;                                                                     \
        }                                                                                   \
    }                                                                                       \
                                                                                            \
    /* inverse DCT */                                                                       \
    idct##bsize##_1d(tmp_block1, tmp_block2, 1, bsize, 1, bsize, 0);                        \
    idct##bsize##_1d(dst, tmp_block1, dst_linesize, 1, bsize, 1, 1);                        \
}                                                                                           \
                                                                                            \
static void filter_freq_sigma_##bsize(DCTdnoizContext *s,                                   \
                                      const float *src, int src_linesize,                   \
                                      float *dst, int dst_linesize, int thread_id)          \
{                                                                                           \
    filter_freq_##bsize(src, src_linesize, dst, dst_linesize, NULL, NULL, s->th);           \
}                                                                                           \
                                                                                            \
static void filter_freq_expr_##bsize(DCTdnoizContext *s,                                    \
                                     const float *src, int src_linesize,                    \
                                     float *dst, int dst_linesize, int thread_id)           \
{                                                                                           \
    filter_freq_##bsize(src, src_linesize, dst, dst_linesize,                               \
                        s->expr[thread_id], s->var_values[thread_id], 0);                   \
}

DEF_FILTER_FREQ_FUNCS(8)
DEF_FILTER_FREQ_FUNCS(16)

#define DCT3X3_0_0  0.5773502691896258f /*  1/sqrt(3) */
#define DCT3X3_0_1  0.5773502691896258f /*  1/sqrt(3) */
#define DCT3X3_0_2  0.5773502691896258f /*  1/sqrt(3) */
#define DCT3X3_1_0  0.7071067811865475f /*  1/sqrt(2) */
#define DCT3X3_1_2 -0.7071067811865475f /* -1/sqrt(2) */
#define DCT3X3_2_0  0.4082482904638631f /*  1/sqrt(6) */
#define DCT3X3_2_1 -0.8164965809277261f /* -2/sqrt(6) */
#define DCT3X3_2_2  0.4082482904638631f /*  1/sqrt(6) */

static av_always_inline void color_decorrelation(float **dst, int dst_linesize,
                                                 const uint8_t *src, int src_linesize,
                                                 int w, int h,
                                                 int r, int g, int b)
{
    int x, y;
    float *dstp_r = dst[0];
    float *dstp_g = dst[1];
    float *dstp_b = dst[2];

    for (y = 0; y < h; y++) {
        const uint8_t *srcp = src;

        for (x = 0; x < w; x++) {
            dstp_r[x] = srcp[r] * DCT3X3_0_0 + srcp[g] * DCT3X3_0_1 + srcp[b] * DCT3X3_0_2;
            dstp_g[x] = srcp[r] * DCT3X3_1_0 +                        srcp[b] * DCT3X3_1_2;
            dstp_b[x] = srcp[r] * DCT3X3_2_0 + srcp[g] * DCT3X3_2_1 + srcp[b] * DCT3X3_2_2;
            srcp += 3;
        }
        src += src_linesize;
        dstp_r += dst_linesize;
        dstp_g += dst_linesize;
        dstp_b += dst_linesize;
    }
}

static av_always_inline void color_correlation(uint8_t *dst, int dst_linesize,
                                               float **src, int src_linesize,
                                               int w, int h,
                                               int r, int g, int b)
{
    int x, y;
    const float *src_r = src[0];
    const float *src_g = src[1];
    const float *src_b = src[2];

    for (y = 0; y < h; y++) {
        uint8_t *dstp = dst;

        for (x = 0; x < w; x++) {
            dstp[r] = av_clip_uint8(src_r[x] * DCT3X3_0_0 + src_g[x] * DCT3X3_1_0 + src_b[x] * DCT3X3_2_0);
            dstp[g] = av_clip_uint8(src_r[x] * DCT3X3_0_1 +                         src_b[x] * DCT3X3_2_1);
            dstp[b] = av_clip_uint8(src_r[x] * DCT3X3_0_2 + src_g[x] * DCT3X3_1_2 + src_b[x] * DCT3X3_2_2);
            dstp += 3;
        }
        dst += dst_linesize;
        src_r += src_linesize;
        src_g += src_linesize;
        src_b += src_linesize;
    }
}

#define DECLARE_COLOR_FUNCS(name, r, g, b)                                          \
static void color_decorrelation_##name(float **dst, int dst_linesize,               \
                                       const uint8_t *src, int src_linesize,        \
                                       int w, int h)                                \
{                                                                                   \
    color_decorrelation(dst, dst_linesize, src, src_linesize, w, h, r, g, b);       \
}                                                                                   \
                                                                                    \
static void color_correlation_##name(uint8_t *dst, int dst_linesize,                \
                                     float **src, int src_linesize,                 \
                                     int w, int h)                                  \
{                                                                                   \
    color_correlation(dst, dst_linesize, src, src_linesize, w, h, r, g, b);         \
}

DECLARE_COLOR_FUNCS(rgb, 0, 1, 2)
DECLARE_COLOR_FUNCS(bgr, 2, 1, 0)

static int config_input(AVFilterLink *inlink)
{
    AVFilterContext *ctx = inlink->dst;
    DCTdnoizContext *s = ctx->priv;
    int i, x, y, bx, by, linesize, *iweights, max_slice_h, slice_h;
    const int bsize = 1 << s->n;

    switch (inlink->format) {
    case AV_PIX_FMT_BGR24:
        s->color_decorrelation = color_decorrelation_bgr;
        s->color_correlation   = color_correlation_bgr;
        break;
    case AV_PIX_FMT_RGB24:
        s->color_decorrelation = color_decorrelation_rgb;
        s->color_correlation   = color_correlation_rgb;
        break;
    default:
        av_assert0(0);
    }

    s->pr_width  = inlink->w - (inlink->w - bsize) % s->step;
    s->pr_height = inlink->h - (inlink->h - bsize) % s->step;
    if (s->pr_width != inlink->w)
        av_log(ctx, AV_LOG_WARNING, "The last %d horizontal pixels won't be denoised\n",
               inlink->w - s->pr_width);
    if (s->pr_height != inlink->h)
        av_log(ctx, AV_LOG_WARNING, "The last %d vertical pixels won't be denoised\n",
               inlink->h - s->pr_height);

    max_slice_h = s->pr_height / ((s->bsize - 1) * 2);
    s->nb_threads = FFMIN3(MAX_THREADS, ctx->graph->nb_threads, max_slice_h);
    av_log(ctx, AV_LOG_DEBUG, "threads: [max=%d hmax=%d user=%d] => %d\n",
           MAX_THREADS, max_slice_h, ctx->graph->nb_threads, s->nb_threads);

    s->p_linesize = linesize = FFALIGN(s->pr_width, 32);
    for (i = 0; i < 2; i++) {
        s->cbuf[i][0] = av_malloc(linesize * s->pr_height * sizeof(*s->cbuf[i][0]));
        s->cbuf[i][1] = av_malloc(linesize * s->pr_height * sizeof(*s->cbuf[i][1]));
        s->cbuf[i][2] = av_malloc(linesize * s->pr_height * sizeof(*s->cbuf[i][2]));
        if (!s->cbuf[i][0] || !s->cbuf[i][1] || !s->cbuf[i][2])
            return AVERROR(ENOMEM);
    }

    /* eval expressions are probably not thread safe when the eval internal
     * state can be changed (typically through load & store operations) */
    if (s->expr_str) {
        for (i = 0; i < s->nb_threads; i++) {
            int ret = av_expr_parse(&s->expr[i], s->expr_str, var_names,
                                    NULL, NULL, NULL, NULL, 0, ctx);
            if (ret < 0)
                return ret;
        }
    }

    /* each slice will need to (pre & re)process the top and bottom block of
     * the previous one in in addition to its processing area. This is because
     * each pixel is averaged by all the surrounding blocks */
    slice_h = (int)ceilf(s->pr_height / s->nb_threads) + (s->bsize - 1) * 2;
    for (i = 0; i < s->nb_threads; i++) {
        s->slices[i] = av_malloc_array(linesize, slice_h * sizeof(*s->slices[i]));
        if (!s->slices[i])
            return AVERROR(ENOMEM);
    }

    s->weights = av_malloc(s->pr_height * linesize * sizeof(*s->weights));
    if (!s->weights)
        return AVERROR(ENOMEM);
    iweights = av_calloc(s->pr_height, linesize * sizeof(*iweights));
    if (!iweights)
        return AVERROR(ENOMEM);
    for (y = 0; y < s->pr_height - bsize + 1; y += s->step)
        for (x = 0; x < s->pr_width - bsize + 1; x += s->step)
            for (by = 0; by < bsize; by++)
                for (bx = 0; bx < bsize; bx++)
                    iweights[(y + by)*linesize + x + bx]++;
    for (y = 0; y < s->pr_height; y++)
        for (x = 0; x < s->pr_width; x++)
            s->weights[y*linesize + x] = 1. / iweights[y*linesize + x];
    av_free(iweights);

    return 0;
}

static av_cold int init(AVFilterContext *ctx)
{
    DCTdnoizContext *s = ctx->priv;

    s->bsize = 1 << s->n;
    if (s->overlap == -1)
        s->overlap = s->bsize - 1;

    if (s->overlap > s->bsize - 1) {
        av_log(s, AV_LOG_ERROR, "Overlap value can not except %d "
               "with a block size of %dx%d\n",
               s->bsize - 1, s->bsize, s->bsize);
        return AVERROR(EINVAL);
    }

    if (s->expr_str) {
        switch (s->n) {
        case 3: s->filter_freq_func = filter_freq_expr_8;  break;
        case 4: s->filter_freq_func = filter_freq_expr_16; break;
        default: av_assert0(0);
        }
    } else {
        switch (s->n) {
        case 3: s->filter_freq_func = filter_freq_sigma_8;  break;
        case 4: s->filter_freq_func = filter_freq_sigma_16; break;
        default: av_assert0(0);
        }
    }

    s->th   = s->sigma * 3.;
    s->step = s->bsize - s->overlap;
    return 0;
}

static int query_formats(AVFilterContext *ctx)
{
    static const enum AVPixelFormat pix_fmts[] = {
        AV_PIX_FMT_BGR24, AV_PIX_FMT_RGB24,
        AV_PIX_FMT_NONE
    };
    ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
    return 0;
}

typedef struct ThreadData {
    float *src, *dst;
} ThreadData;

static int filter_slice(AVFilterContext *ctx,
                        void *arg, int jobnr, int nb_jobs)
{
    int x, y;
    DCTdnoizContext *s = ctx->priv;
    const ThreadData *td = arg;
    const int w = s->pr_width;
    const int h = s->pr_height;
    const int slice_start = (h *  jobnr   ) / nb_jobs;
    const int slice_end   = (h * (jobnr+1)) / nb_jobs;
    const int slice_start_ctx = FFMAX(slice_start - s->bsize + 1, 0);
    const int slice_end_ctx   = FFMIN(slice_end, h - s->bsize + 1);
    const int slice_h = slice_end_ctx - slice_start_ctx;
    const int src_linesize   = s->p_linesize;
    const int dst_linesize   = s->p_linesize;
    const int slice_linesize = s->p_linesize;
    float *dst;
    const float *src = td->src + slice_start_ctx * src_linesize;
    const float *weights = s->weights + slice_start * dst_linesize;
    float *slice = s->slices[jobnr];

    // reset block sums
    memset(slice, 0, (slice_h + s->bsize - 1) * dst_linesize * sizeof(*slice));

    // block dct sums
    for (y = 0; y < slice_h; y += s->step) {
        for (x = 0; x < w - s->bsize + 1; x += s->step)
            s->filter_freq_func(s, src + x, src_linesize,
                                slice + x, slice_linesize,
                                jobnr);
        src += s->step * src_linesize;
        slice += s->step * slice_linesize;
    }

    // average blocks
    slice = s->slices[jobnr] + (slice_start - slice_start_ctx) * slice_linesize;
    dst = td->dst + slice_start * dst_linesize;
    for (y = slice_start; y < slice_end; y++) {
        for (x = 0; x < w; x++)
            dst[x] = slice[x] * weights[x];
        slice += slice_linesize;
        dst += dst_linesize;
        weights += dst_linesize;
    }

    return 0;
}

static int filter_frame(AVFilterLink *inlink, AVFrame *in)
{
    AVFilterContext *ctx = inlink->dst;
    DCTdnoizContext *s = ctx->priv;
    AVFilterLink *outlink = inlink->dst->outputs[0];
    int direct, plane;
    AVFrame *out;

    if (av_frame_is_writable(in)) {
        direct = 1;
        out = in;
    } else {
        direct = 0;
        out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
        if (!out) {
            av_frame_free(&in);
            return AVERROR(ENOMEM);
        }
        av_frame_copy_props(out, in);
    }

    s->color_decorrelation(s->cbuf[0], s->p_linesize,
                           in->data[0], in->linesize[0],
                           s->pr_width, s->pr_height);
    for (plane = 0; plane < 3; plane++) {
        ThreadData td = {
            .src = s->cbuf[0][plane],
            .dst = s->cbuf[1][plane],
        };
        ctx->internal->execute(ctx, filter_slice, &td, NULL, s->nb_threads);
    }
    s->color_correlation(out->data[0], out->linesize[0],
                         s->cbuf[1], s->p_linesize,
                         s->pr_width, s->pr_height);

    if (!direct) {
        int y;
        uint8_t *dst = out->data[0];
        const uint8_t *src = in->data[0];
        const int dst_linesize = out->linesize[0];
        const int src_linesize = in->linesize[0];
        const int hpad = (inlink->w - s->pr_width) * 3;
        const int vpad = (inlink->h - s->pr_height);

        if (hpad) {
            uint8_t       *dstp = dst + s->pr_width * 3;
            const uint8_t *srcp = src + s->pr_width * 3;

            for (y = 0; y < s->pr_height; y++) {
                memcpy(dstp, srcp, hpad);
                dstp += dst_linesize;
                srcp += src_linesize;
            }
        }
        if (vpad) {
            uint8_t       *dstp = dst + s->pr_height * dst_linesize;
            const uint8_t *srcp = src + s->pr_height * src_linesize;

            for (y = 0; y < vpad; y++) {
                memcpy(dstp, srcp, inlink->w * 3);
                dstp += dst_linesize;
                srcp += src_linesize;
            }
        }

        av_frame_free(&in);
    }

    return ff_filter_frame(outlink, out);
}

static av_cold void uninit(AVFilterContext *ctx)
{
    int i;
    DCTdnoizContext *s = ctx->priv;

    av_free(s->weights);
    for (i = 0; i < 2; i++) {
        av_free(s->cbuf[i][0]);
        av_free(s->cbuf[i][1]);
        av_free(s->cbuf[i][2]);
    }
    for (i = 0; i < s->nb_threads; i++) {
        av_free(s->slices[i]);
        av_expr_free(s->expr[i]);
    }
}

static const AVFilterPad dctdnoiz_inputs[] = {
    {
        .name         = "default",
        .type         = AVMEDIA_TYPE_VIDEO,
        .filter_frame = filter_frame,
        .config_props = config_input,
    },
    { NULL }
};

static const AVFilterPad dctdnoiz_outputs[] = {
    {
        .name = "default",
        .type = AVMEDIA_TYPE_VIDEO,
    },
    { NULL }
};

AVFilter ff_vf_dctdnoiz = {
    .name          = "dctdnoiz",
    .description   = NULL_IF_CONFIG_SMALL("Denoise frames using 2D DCT."),
    .priv_size     = sizeof(DCTdnoizContext),
    .init          = init,
    .uninit        = uninit,
    .query_formats = query_formats,
    .inputs        = dctdnoiz_inputs,
    .outputs       = dctdnoiz_outputs,
    .priv_class    = &dctdnoiz_class,
    .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,
};