aboutsummaryrefslogtreecommitdiffstats
path: root/libavcodec/flashsv2enc.c
blob: 65db112696760cad31b3abead0b80bd68a96cb7c (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
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
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
/*
 * Flash Screen Video Version 2 encoder
 * Copyright (C) 2009 Joshua Warner
 *
 * 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
 * Flash Screen Video Version 2 encoder
 * @author Joshua Warner
 */

/* Differences from version 1 stream:
 * NOTE: Currently, the only player that supports version 2 streams is Adobe Flash Player itself.
 * * Supports sending only a range of scanlines in a block,
 *   indicating a difference from the corresponding block in the last keyframe.
 * * Supports initializing the zlib dictionary with data from the corresponding
 *   block in the last keyframe, to improve compression.
 * * Supports a hybrid 15-bit rgb / 7-bit palette color space.
 */

/* TODO:
 * Don't keep Block structures for both current frame and keyframe.
 * Make better heuristics for deciding stream parameters (optimum_* functions).  Currently these return constants.
 * Figure out how to encode palette information in the stream, choose an optimum palette at each keyframe.
 * Figure out how the zlibPrimeCompressCurrent flag works, implement support.
 * Find other sample files (that weren't generated here), develop a decoder.
 */

#include <stdio.h>
#include <stdlib.h>
#include <zlib.h>

#include "libavutil/imgutils.h"
#include "avcodec.h"
#include "internal.h"
#include "put_bits.h"
#include "bytestream.h"

#define HAS_IFRAME_IMAGE 0x02
#define HAS_PALLET_INFO 0x01

#define COLORSPACE_BGR 0x00
#define COLORSPACE_15_7 0x10
#define HAS_DIFF_BLOCKS 0x04
#define ZLIB_PRIME_COMPRESS_CURRENT 0x02
#define ZLIB_PRIME_COMPRESS_PREVIOUS 0x01

// Disables experimental "smart" parameter-choosing code, as well as the statistics that it depends on.
// At the moment, the "smart" code is a great example of how the parameters *shouldn't* be chosen.
#define FLASHSV2_DUMB

typedef struct Block {
    uint8_t *enc;
    uint8_t *sl_begin, *sl_end;
    int enc_size;
    uint8_t *data;
    unsigned long data_size;

    uint8_t start, len;
    uint8_t dirty;
    uint8_t col, row, width, height;
    uint8_t flags;
} Block;

typedef struct Palette {
    unsigned colors[128];
    uint8_t index[1 << 15];
} Palette;

typedef struct FlashSV2Context {
    AVCodecContext *avctx;
    uint8_t *current_frame;
    uint8_t *key_frame;
    uint8_t *encbuffer;
    uint8_t *keybuffer;
    uint8_t *databuffer;

    uint8_t *blockbuffer;
    int blockbuffer_size;

    Block *frame_blocks;
    Block *key_blocks;
    int frame_size;
    int blocks_size;

    int use15_7, dist, comp;

    int rows, cols;

    int last_key_frame;

    int image_width, image_height;
    int block_width, block_height;
    uint8_t flags;
    uint8_t use_custom_palette;
    uint8_t palette_type;       ///< 0=>default, 1=>custom - changed when palette regenerated.
    Palette palette;
#ifndef FLASHSV2_DUMB
    double tot_blocks;          ///< blocks encoded since last keyframe
    double diff_blocks;         ///< blocks that were different since last keyframe
    double tot_lines;           ///< total scanlines in image since last keyframe
    double diff_lines;          ///< scanlines that were different since last keyframe
    double raw_size;            ///< size of raw frames since last keyframe
    double comp_size;           ///< size of compressed data since last keyframe
    double uncomp_size;         ///< size of uncompressed data since last keyframe

    double total_bits;          ///< total bits written to stream so far
#endif
} FlashSV2Context;

static av_cold void cleanup(FlashSV2Context * s)
{
    av_freep(&s->encbuffer);
    av_freep(&s->keybuffer);
    av_freep(&s->databuffer);
    av_freep(&s->blockbuffer);
    av_freep(&s->current_frame);
    av_freep(&s->key_frame);

    av_freep(&s->frame_blocks);
    av_freep(&s->key_blocks);
}

static void init_blocks(FlashSV2Context * s, Block * blocks,
                        uint8_t * encbuf, uint8_t * databuf)
{
    int row, col;
    Block *b;
    for (col = 0; col < s->cols; col++) {
        for (row = 0; row < s->rows; row++) {
            b = blocks + (col + row * s->cols);
            b->width = (col < s->cols - 1) ?
                s->block_width :
                s->image_width - col * s->block_width;

            b->height = (row < s->rows - 1) ?
                s->block_height :
                s->image_height - row * s->block_height;

            b->row   = row;
            b->col   = col;
            b->enc   = encbuf;
            b->data  = databuf;
            encbuf  += b->width * b->height * 3;
            databuf += !databuf ? 0 : b->width * b->height * 6;
        }
    }
}

static void reset_stats(FlashSV2Context * s)
{
#ifndef FLASHSV2_DUMB
    s->diff_blocks = 0.1;
    s->tot_blocks = 1;
    s->diff_lines = 0.1;
    s->tot_lines = 1;
    s->raw_size = s->comp_size = s->uncomp_size = 10;
#endif
}

static av_cold int flashsv2_encode_init(AVCodecContext * avctx)
{
    FlashSV2Context *s = avctx->priv_data;

    s->avctx = avctx;

    s->comp = avctx->compression_level;
    if (s->comp == -1)
        s->comp = 9;
    if (s->comp < 0 || s->comp > 9) {
        av_log(avctx, AV_LOG_ERROR,
               "Compression level should be 0-9, not %d\n", s->comp);
        return -1;
    }


    if ((avctx->width > 4095) || (avctx->height > 4095)) {
        av_log(avctx, AV_LOG_ERROR,
               "Input dimensions too large, input must be max 4095x4095 !\n");
        return -1;
    }
    if ((avctx->width < 16) || (avctx->height < 16)) {
        av_log(avctx, AV_LOG_ERROR,
               "Input dimensions too small, input must be at least 16x16 !\n");
        return -1;
    }

    if (av_image_check_size(avctx->width, avctx->height, 0, avctx) < 0)
        return -1;


    s->last_key_frame = 0;

    s->image_width  = avctx->width;
    s->image_height = avctx->height;

    s->block_width  = (s->image_width /  12) & ~15;
    s->block_height = (s->image_height / 12) & ~15;

    if(!s->block_width)
        s->block_width = 1;
    if(!s->block_height)
        s->block_height = 1;

    s->rows = (s->image_height + s->block_height - 1) / s->block_height;
    s->cols = (s->image_width +  s->block_width -  1) / s->block_width;

    s->frame_size  = s->image_width * s->image_height * 3;
    s->blocks_size = s->rows * s->cols * sizeof(Block);

    s->encbuffer     = av_mallocz(s->frame_size);
    s->keybuffer     = av_mallocz(s->frame_size);
    s->databuffer    = av_mallocz(s->frame_size * 6);
    s->current_frame = av_mallocz(s->frame_size);
    s->key_frame     = av_mallocz(s->frame_size);
    s->frame_blocks  = av_mallocz(s->blocks_size);
    s->key_blocks    = av_mallocz(s->blocks_size);

    s->blockbuffer      = NULL;
    s->blockbuffer_size = 0;

    init_blocks(s, s->frame_blocks, s->encbuffer, s->databuffer);
    init_blocks(s, s->key_blocks,   s->keybuffer, 0);
    reset_stats(s);
#ifndef FLASHSV2_DUMB
    s->total_bits = 1;
#endif

    s->use_custom_palette =  0;
    s->palette_type       = -1;        // so that the palette will be generated in reconfigure_at_keyframe

    if (!s->encbuffer || !s->keybuffer || !s->databuffer
        || !s->current_frame || !s->key_frame || !s->key_blocks
        || !s->frame_blocks) {
        av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
        cleanup(s);
        return -1;
    }

    return 0;
}

static int new_key_frame(FlashSV2Context * s)
{
    int i;
    memcpy(s->key_blocks, s->frame_blocks, s->blocks_size);
    memcpy(s->key_frame, s->current_frame, s->frame_size);

    for (i = 0; i < s->rows * s->cols; i++) {
        s->key_blocks[i].enc += (s->keybuffer - s->encbuffer);
        s->key_blocks[i].sl_begin = 0;
        s->key_blocks[i].sl_end   = 0;
        s->key_blocks[i].data     = 0;
    }
    memcpy(s->keybuffer, s->encbuffer, s->frame_size);

    return 0;
}

static int write_palette(FlashSV2Context * s, uint8_t * buf, int buf_size)
{
    //this isn't implemented yet!  Default palette only!
    return -1;
}

static int write_header(FlashSV2Context * s, uint8_t * buf, int buf_size)
{
    PutBitContext pb;
    int buf_pos, len;

    if (buf_size < 5)
        return -1;

    init_put_bits(&pb, buf, buf_size);

    put_bits(&pb, 4, (s->block_width  >> 4) - 1);
    put_bits(&pb, 12, s->image_width);
    put_bits(&pb, 4, (s->block_height >> 4) - 1);
    put_bits(&pb, 12, s->image_height);

    flush_put_bits(&pb);
    buf_pos = 4;

    buf[buf_pos++] = s->flags;

    if (s->flags & HAS_PALLET_INFO) {
        len = write_palette(s, buf + buf_pos, buf_size - buf_pos);
        if (len < 0)
            return -1;
        buf_pos += len;
    }

    return buf_pos;
}

static int write_block(Block * b, uint8_t * buf, int buf_size)
{
    int buf_pos = 0;
    unsigned block_size = b->data_size;

    if (b->flags & HAS_DIFF_BLOCKS)
        block_size += 2;
    if (b->flags & ZLIB_PRIME_COMPRESS_CURRENT)
        block_size += 2;
    if (block_size > 0)
        block_size += 1;
    if (buf_size < block_size + 2)
        return -1;

    buf[buf_pos++] = block_size >> 8;
    buf[buf_pos++] = block_size;

    if (block_size == 0)
        return buf_pos;

    buf[buf_pos++] = b->flags;

    if (b->flags & HAS_DIFF_BLOCKS) {
        buf[buf_pos++] = (b->start);
        buf[buf_pos++] = (b->len);
    }

    if (b->flags & ZLIB_PRIME_COMPRESS_CURRENT) {
        //This feature of the format is poorly understood, and as of now, unused.
        buf[buf_pos++] = (b->col);
        buf[buf_pos++] = (b->row);
    }

    memcpy(buf + buf_pos, b->data, b->data_size);

    buf_pos += b->data_size;

    return buf_pos;
}

static int encode_zlib(Block * b, uint8_t * buf, unsigned long *buf_size, int comp)
{
    int res = compress2(buf, buf_size, b->sl_begin, b->sl_end - b->sl_begin, comp);
    return res == Z_OK ? 0 : -1;
}

static int encode_zlibprime(Block * b, Block * prime, uint8_t * buf,
                            int *buf_size, int comp)
{
    z_stream s;
    int res;
    s.zalloc = NULL;
    s.zfree  = NULL;
    s.opaque = NULL;
    res = deflateInit(&s, comp);
    if (res < 0)
        return -1;

    s.next_in  = prime->enc;
    s.avail_in = prime->enc_size;
    while (s.avail_in > 0) {
        s.next_out  = buf;
        s.avail_out = *buf_size;
        res = deflate(&s, Z_SYNC_FLUSH);
        if (res < 0)
            return -1;
    }

    s.next_in   = b->sl_begin;
    s.avail_in  = b->sl_end - b->sl_begin;
    s.next_out  = buf;
    s.avail_out = *buf_size;
    res = deflate(&s, Z_FINISH);
    deflateEnd(&s);
    *buf_size -= s.avail_out;
    if (res != Z_STREAM_END)
        return -1;
    return 0;
}

static int encode_bgr(Block * b, const uint8_t * src, int stride)
{
    int i;
    uint8_t *ptr = b->enc;
    for (i = 0; i < b->start; i++)
        memcpy(ptr + i * b->width * 3, src + i * stride, b->width * 3);
    b->sl_begin = ptr + i * b->width * 3;
    for (; i < b->start + b->len; i++)
        memcpy(ptr + i * b->width * 3, src + i * stride, b->width * 3);
    b->sl_end = ptr + i * b->width * 3;
    for (; i < b->height; i++)
        memcpy(ptr + i * b->width * 3, src + i * stride, b->width * 3);
    b->enc_size = ptr + i * b->width * 3 - b->enc;
    return b->enc_size;
}

static inline unsigned pixel_color15(const uint8_t * src)
{
    return (src[0] >> 3) | ((src[1] & 0xf8) << 2) | ((src[2] & 0xf8) << 7);
}

static inline unsigned int chroma_diff(unsigned int c1, unsigned int c2)
{
#define ABSDIFF(a,b) (abs((int)(a)-(int)(b)))

    unsigned int t1 = (c1 & 0x000000ff) + ((c1 & 0x0000ff00) >> 8) + ((c1 & 0x00ff0000) >> 16);
    unsigned int t2 = (c2 & 0x000000ff) + ((c2 & 0x0000ff00) >> 8) + ((c2 & 0x00ff0000) >> 16);

    return ABSDIFF(t1, t2) + ABSDIFF(c1 & 0x000000ff, c2 & 0x000000ff) +
        ABSDIFF((c1 & 0x0000ff00) >> 8 , (c2 & 0x0000ff00) >> 8) +
        ABSDIFF((c1 & 0x00ff0000) >> 16, (c2 & 0x00ff0000) >> 16);
}

static inline int pixel_color7_fast(Palette * palette, unsigned c15)
{
    return palette->index[c15];
}

static int pixel_color7_slow(Palette * palette, unsigned color)
{
    int i, min = 0x7fffffff;
    int minc = -1;
    for (i = 0; i < 128; i++) {
        int c1 = palette->colors[i];
        int diff = chroma_diff(c1, color);
        if (diff < min) {
            min = diff;
            minc = i;
        }
    }
    return minc;
}

static inline unsigned pixel_bgr(const uint8_t * src)
{
    return (src[0]) | (src[1] << 8) | (src[2] << 16);
}

static int write_pixel_15_7(Palette * palette, uint8_t * dest, const uint8_t * src,
                            int dist)
{
    unsigned c15 = pixel_color15(src);
    unsigned color = pixel_bgr(src);
    int d15 = chroma_diff(color, color & 0x00f8f8f8);
    int c7 = pixel_color7_fast(palette, c15);
    int d7 = chroma_diff(color, palette->colors[c7]);
    if (dist + d15 >= d7) {
        dest[0] = c7;
        return 1;
    } else {
        dest[0] = 0x80 | (c15 >> 8);
        dest[1] = c15 & 0xff;
        return 2;
    }
}

static int update_palette_index(Palette * palette)
{
    int r, g, b;
    unsigned int bgr, c15, index;
    for (r = 4; r < 256; r += 8) {
        for (g = 4; g < 256; g += 8) {
            for (b = 4; b < 256; b += 8) {
                bgr = b | (g << 8) | (r << 16);
                c15 = (b >> 3) | ((g & 0xf8) << 2) | ((r & 0xf8) << 7);
                index = pixel_color7_slow(palette, bgr);

                palette->index[c15] = index;
            }
        }
    }
    return 0;
}

static const unsigned int default_screen_video_v2_palette[128] = {
    0x00000000, 0x00333333, 0x00666666, 0x00999999, 0x00CCCCCC, 0x00FFFFFF,
    0x00330000, 0x00660000, 0x00990000, 0x00CC0000, 0x00FF0000, 0x00003300,
    0x00006600, 0x00009900, 0x0000CC00, 0x0000FF00, 0x00000033, 0x00000066,
    0x00000099, 0x000000CC, 0x000000FF, 0x00333300, 0x00666600, 0x00999900,
    0x00CCCC00, 0x00FFFF00, 0x00003333, 0x00006666, 0x00009999, 0x0000CCCC,
    0x0000FFFF, 0x00330033, 0x00660066, 0x00990099, 0x00CC00CC, 0x00FF00FF,
    0x00FFFF33, 0x00FFFF66, 0x00FFFF99, 0x00FFFFCC, 0x00FF33FF, 0x00FF66FF,
    0x00FF99FF, 0x00FFCCFF, 0x0033FFFF, 0x0066FFFF, 0x0099FFFF, 0x00CCFFFF,
    0x00CCCC33, 0x00CCCC66, 0x00CCCC99, 0x00CCCCFF, 0x00CC33CC, 0x00CC66CC,
    0x00CC99CC, 0x00CCFFCC, 0x0033CCCC, 0x0066CCCC, 0x0099CCCC, 0x00FFCCCC,
    0x00999933, 0x00999966, 0x009999CC, 0x009999FF, 0x00993399, 0x00996699,
    0x0099CC99, 0x0099FF99, 0x00339999, 0x00669999, 0x00CC9999, 0x00FF9999,
    0x00666633, 0x00666699, 0x006666CC, 0x006666FF, 0x00663366, 0x00669966,
    0x0066CC66, 0x0066FF66, 0x00336666, 0x00996666, 0x00CC6666, 0x00FF6666,
    0x00333366, 0x00333399, 0x003333CC, 0x003333FF, 0x00336633, 0x00339933,
    0x0033CC33, 0x0033FF33, 0x00663333, 0x00993333, 0x00CC3333, 0x00FF3333,
    0x00003366, 0x00336600, 0x00660033, 0x00006633, 0x00330066, 0x00663300,
    0x00336699, 0x00669933, 0x00993366, 0x00339966, 0x00663399, 0x00996633,
    0x006699CC, 0x0099CC66, 0x00CC6699, 0x0066CC99, 0x009966CC, 0x00CC9966,
    0x0099CCFF, 0x00CCFF99, 0x00FF99CC, 0x0099FFCC, 0x00CC99FF, 0x00FFCC99,
    0x00111111, 0x00222222, 0x00444444, 0x00555555, 0x00AAAAAA, 0x00BBBBBB,
    0x00DDDDDD, 0x00EEEEEE
};

static int generate_default_palette(Palette * palette)
{
    memcpy(palette->colors, default_screen_video_v2_palette,
           sizeof(default_screen_video_v2_palette));

    return update_palette_index(palette);
}

static int generate_optimum_palette(Palette * palette, const uint8_t * image,
                                   int width, int height, int stride)
{
    //this isn't implemented yet!  Default palette only!
    return -1;
}

static inline int encode_15_7_sl(Palette * palette, uint8_t * dest,
                                 const uint8_t * src, int width, int dist)
{
    int len = 0, x;
    for (x = 0; x < width; x++) {
        len += write_pixel_15_7(palette, dest + len, src + 3 * x, dist);
    }
    return len;
}

static int encode_15_7(Palette * palette, Block * b, const uint8_t * src,
                       int stride, int dist)
{
    int i;
    uint8_t *ptr = b->enc;
    for (i = 0; i < b->start; i++)
        ptr += encode_15_7_sl(palette, ptr, src + i * stride, b->width, dist);
    b->sl_begin = ptr;
    for (; i < b->start + b->len; i++)
        ptr += encode_15_7_sl(palette, ptr, src + i * stride, b->width, dist);
    b->sl_end = ptr;
    for (; i < b->height; i++)
        ptr += encode_15_7_sl(palette, ptr, src + i * stride, b->width, dist);
    b->enc_size = ptr - b->enc;
    return b->enc_size;
}

static int encode_block(FlashSV2Context *s, Palette * palette, Block * b,
                        Block * prev, const uint8_t * src, int stride, int comp,
                        int dist, int keyframe)
{
    unsigned buf_size = b->width * b->height * 6;
    uint8_t *buf = s->blockbuffer;
    int res;

    if (b->flags & COLORSPACE_15_7) {
        encode_15_7(palette, b, src, stride, dist);
    } else {
        encode_bgr(b, src, stride);
    }

    if (b->len > 0) {
        b->data_size = buf_size;
        res = encode_zlib(b, b->data, &b->data_size, comp);
        if (res)
            return res;

        if (!keyframe) {
            res = encode_zlibprime(b, prev, buf, &buf_size, comp);
            if (res)
                return res;

            if (buf_size < b->data_size) {
                b->data_size = buf_size;
                memcpy(b->data, buf, buf_size);
                b->flags |= ZLIB_PRIME_COMPRESS_PREVIOUS;
            }
        }
    } else {
        b->data_size = 0;
    }
    return 0;
}

static int compare_sl(FlashSV2Context * s, Block * b, const uint8_t * src,
                      uint8_t * frame, uint8_t * key, int y, int keyframe)
{
    if (memcmp(src, frame, b->width * 3) != 0) {
        b->dirty = 1;
        memcpy(frame, src, b->width * 3);
#ifndef FLASHSV2_DUMB
        s->diff_lines++;
#endif
    }
    if (memcmp(src, key, b->width * 3) != 0) {
        if (b->len == 0)
            b->start = y;
        b->len = y + 1 - b->start;
    }
    return 0;
}

static int mark_all_blocks(FlashSV2Context * s, const uint8_t * src, int stride,
                           int keyframe)
{
    int sl, rsl, col, pos, possl;
    Block *b;
    for (sl = s->image_height - 1; sl >= 0; sl--) {
        for (col = 0; col < s->cols; col++) {
            rsl = s->image_height - sl - 1;
            b = s->frame_blocks + col + rsl / s->block_height * s->cols;
            possl = stride * sl + col * s->block_width * 3;
            pos = s->image_width * rsl * 3 + col * s->block_width * 3;
            compare_sl(s, b, src + possl, s->current_frame + pos,
                       s->key_frame + pos, rsl % s->block_height, keyframe);
        }
    }
#ifndef FLASHSV2_DUMB
    s->tot_lines += s->image_height * s->cols;
#endif
    return 0;
}

static int encode_all_blocks(FlashSV2Context * s, int keyframe)
{
    int row, col, res;
    uint8_t *data;
    Block *b, *prev;
    for (row = 0; row < s->rows; row++) {
        for (col = 0; col < s->cols; col++) {
            b = s->frame_blocks + (row * s->cols + col);
            prev = s->key_blocks + (row * s->cols + col);
            b->flags = s->use15_7 ? COLORSPACE_15_7 : 0;
            if (keyframe) {
                b->start = 0;
                b->len = b->height;
            } else if (!b->dirty) {
                b->start = 0;
                b->len = 0;
                b->data_size = 0;
                continue;
            } else if (b->start != 0 || b->len != b->height) {
                b->flags |= HAS_DIFF_BLOCKS;
            }
            data = s->current_frame + s->image_width * 3 * s->block_height * row + s->block_width * col * 3;
            res = encode_block(s, &s->palette, b, prev, data, s->image_width * 3, s->comp, s->dist, keyframe);
#ifndef FLASHSV2_DUMB
            if (b->dirty)
                s->diff_blocks++;
            s->comp_size += b->data_size;
            s->uncomp_size += b->enc_size;
#endif
            if (res)
                return res;
        }
    }
#ifndef FLASHSV2_DUMB
    s->raw_size += s->image_width * s->image_height * 3;
    s->tot_blocks += s->rows * s->cols;
#endif
    return 0;
}

static int write_all_blocks(FlashSV2Context * s, uint8_t * buf,
                            int buf_size)
{
    int row, col, buf_pos = 0, len;
    Block *b;
    for (row = 0; row < s->rows; row++) {
        for (col = 0; col < s->cols; col++) {
            b = s->frame_blocks + row * s->cols + col;
            len = write_block(b, buf + buf_pos, buf_size - buf_pos);
            b->start = b->len = b->dirty = 0;
            if (len < 0)
                return len;
            buf_pos += len;
        }
    }
    return buf_pos;
}

static int write_bitstream(FlashSV2Context * s, const uint8_t * src, int stride,
                           uint8_t * buf, int buf_size, int keyframe)
{
    int buf_pos, res;

    res = mark_all_blocks(s, src, stride, keyframe);
    if (res)
        return res;
    res = encode_all_blocks(s, keyframe);
    if (res)
        return res;

    res = write_header(s, buf, buf_size);
    if (res < 0) {
        return res;
    } else {
        buf_pos = res;
    }
    res = write_all_blocks(s, buf + buf_pos, buf_size - buf_pos);
    if (res < 0)
        return res;
    buf_pos += res;
#ifndef FLASHSV2_DUMB
    s->total_bits += ((double) buf_pos) * 8.0;
#endif

    return buf_pos;
}

static void recommend_keyframe(FlashSV2Context * s, int *keyframe)
{
#ifndef FLASHSV2_DUMB
    double block_ratio, line_ratio, enc_ratio, comp_ratio, data_ratio;
    if (s->avctx->gop_size > 0) {
        block_ratio = s->diff_blocks / s->tot_blocks;
        line_ratio = s->diff_lines / s->tot_lines;
        enc_ratio = s->uncomp_size / s->raw_size;
        comp_ratio = s->comp_size / s->uncomp_size;
        data_ratio = s->comp_size / s->raw_size;

        if ((block_ratio >= 0.5 && line_ratio / block_ratio <= 0.5) || line_ratio >= 0.95) {
            *keyframe = 1;
            return;
        }
    }
#else
    return;
#endif
}

#ifndef FLASHSV2_DUMB
static const double block_size_fraction = 1.0 / 300;
static const double use15_7_threshold = 8192;
static const double color15_7_factor = 100;
#endif
static int optimum_block_width(FlashSV2Context * s)
{
#ifndef FLASHSV2_DUMB
    double save = (1-pow(s->diff_lines/s->diff_blocks/s->block_height, 0.5)) * s->comp_size/s->tot_blocks;
    double width = block_size_fraction * sqrt(0.5 * save * s->rows * s->cols) * s->image_width;
    int pwidth = ((int) width);
    return FFCLIP(pwidth & ~15, 256, 16);
#else
    return 64;
#endif
}

static int optimum_block_height(FlashSV2Context * s)
{
#ifndef FLASHSV2_DUMB
    double save = (1-pow(s->diff_lines/s->diff_blocks/s->block_height, 0.5)) * s->comp_size/s->tot_blocks;
    double height = block_size_fraction * sqrt(0.5 * save * s->rows * s->cols) * s->image_height;
    int pheight = ((int) height);
    return FFCLIP(pheight & ~15, 256, 16);
#else
    return 64;
#endif
}

static int optimum_use15_7(FlashSV2Context * s)
{
#ifndef FLASHSV2_DUMB
    double ideal = ((double)(s->avctx->bit_rate * s->avctx->time_base.den * s->avctx->ticks_per_frame)) /
        ((double) s->avctx->time_base.num) * s->avctx->frame_number;
    if (ideal + use15_7_threshold < s->total_bits) {
        return 1;
    } else {
        return 0;
    }
#else
    return s->avctx->global_quality == 0;
#endif
}

static int optimum_dist(FlashSV2Context * s)
{
#ifndef FLASHSV2_DUMB
    double ideal =
        s->avctx->bit_rate * s->avctx->time_base.den *
        s->avctx->ticks_per_frame;
    int dist = pow((s->total_bits / ideal) * color15_7_factor, 3);
    av_log(s->avctx, AV_LOG_DEBUG, "dist: %d\n", dist);
    return dist;
#else
    return 15;
#endif
}


static int reconfigure_at_keyframe(FlashSV2Context * s, const uint8_t * image,
                                   int stride)
{
    int update_palette = 0;
    int res;
    int block_width  = optimum_block_width (s);
    int block_height = optimum_block_height(s);

    s->rows = (s->image_height + block_height - 1) / block_height;
    s->cols = (s->image_width  + block_width  - 1) / block_width;

    if (block_width != s->block_width || block_height != s->block_height) {
        s->block_width  = block_width;
        s->block_height = block_height;
        if (s->rows * s->cols > s->blocks_size / sizeof(Block)) {
            s->frame_blocks = av_realloc_array(s->frame_blocks, s->rows, s->cols * sizeof(Block));
            s->key_blocks = av_realloc_array(s->key_blocks, s->cols, s->rows * sizeof(Block));
            if (!s->frame_blocks || !s->key_blocks) {
                av_log(s->avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
                return -1;
            }
            s->blocks_size = s->rows * s->cols * sizeof(Block);
        }
        init_blocks(s, s->frame_blocks, s->encbuffer, s->databuffer);
        init_blocks(s, s->key_blocks, s->keybuffer, 0);

        av_fast_malloc(&s->blockbuffer, &s->blockbuffer_size, block_width * block_height * 6);
        if (!s->blockbuffer) {
            av_log(s->avctx, AV_LOG_ERROR, "Could not allocate block buffer.\n");
            return AVERROR(ENOMEM);
        }
    }

    s->use15_7 = optimum_use15_7(s);
    if (s->use15_7) {
        if ((s->use_custom_palette && s->palette_type != 1) || update_palette) {
            res = generate_optimum_palette(&s->palette, image, s->image_width, s->image_height, stride);
            if (res)
                return res;
            s->palette_type = 1;
            av_log(s->avctx, AV_LOG_DEBUG, "Generated optimum palette\n");
        } else if (!s->use_custom_palette && s->palette_type != 0) {
            res = generate_default_palette(&s->palette);
            if (res)
                return res;
            s->palette_type = 0;
            av_log(s->avctx, AV_LOG_DEBUG, "Generated default palette\n");
        }
    }


    reset_stats(s);

    return 0;
}

static int flashsv2_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
                                 const AVFrame *p, int *got_packet)
{
    FlashSV2Context *const s = avctx->priv_data;
    int res;
    int keyframe = 0;

    if ((res = ff_alloc_packet2(avctx, pkt, s->frame_size + AV_INPUT_BUFFER_MIN_SIZE, 0)) < 0)
        return res;

    /* First frame needs to be a keyframe */
    if (avctx->frame_number == 0)
        keyframe = 1;

    /* Check the placement of keyframes */
    if (avctx->gop_size > 0) {
        if (avctx->frame_number >= s->last_key_frame + avctx->gop_size)
            keyframe = 1;
    }

    if (!keyframe
        && avctx->frame_number > s->last_key_frame + avctx->keyint_min) {
        recommend_keyframe(s, &keyframe);
        if (keyframe)
            av_log(avctx, AV_LOG_DEBUG, "Recommending key frame at frame %d\n", avctx->frame_number);
    }

    if (keyframe) {
        res = reconfigure_at_keyframe(s, p->data[0], p->linesize[0]);
        if (res)
            return res;
    }

    if (s->use15_7)
        s->dist = optimum_dist(s);

    res = write_bitstream(s, p->data[0], p->linesize[0], pkt->data, pkt->size, keyframe);

    if (keyframe) {
        new_key_frame(s);
        s->last_key_frame = avctx->frame_number;
        pkt->flags |= AV_PKT_FLAG_KEY;
        av_log(avctx, AV_LOG_DEBUG, "Inserting key frame at frame %d\n", avctx->frame_number);
    }

    pkt->size = res;
    *got_packet = 1;

    return 0;
}

static av_cold int flashsv2_encode_end(AVCodecContext * avctx)
{
    FlashSV2Context *s = avctx->priv_data;

    cleanup(s);

    return 0;
}

AVCodec ff_flashsv2_encoder = {
    .name           = "flashsv2",
    .long_name      = NULL_IF_CONFIG_SMALL("Flash Screen Video Version 2"),
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = AV_CODEC_ID_FLASHSV2,
    .priv_data_size = sizeof(FlashSV2Context),
    .init           = flashsv2_encode_init,
    .encode2        = flashsv2_encode_frame,
    .close          = flashsv2_encode_end,
    .pix_fmts       = (const enum AVPixelFormat[]){ AV_PIX_FMT_BGR24, AV_PIX_FMT_NONE },
};