aboutsummaryrefslogtreecommitdiffstats
path: root/libavcodec/ccaption_dec.c
blob: f91c92b37332caeff7b3ed041174366a1fe53b8b (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
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
/*
 * Closed Caption Decoding
 * Copyright (c) 2015 Anshul Maheshwari
 *
 * 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
 */

#include "avcodec.h"
#include "ass.h"
#include "codec_internal.h"
#include "libavutil/opt.h"

#define SCREEN_ROWS 15
#define SCREEN_COLUMNS 32

#define SET_FLAG(var, val)   ( (var) |=   ( 1 << (val)) )
#define UNSET_FLAG(var, val) ( (var) &=  ~( 1 << (val)) )
#define CHECK_FLAG(var, val) ( (var) &    ( 1 << (val)) )

static const AVRational ms_tb = {1, 1000};

enum cc_mode {
    CCMODE_POPON,
    CCMODE_PAINTON,
    CCMODE_ROLLUP,
    CCMODE_TEXT,
};

enum cc_color_code {
    CCCOL_WHITE,
    CCCOL_GREEN,
    CCCOL_BLUE,
    CCCOL_CYAN,
    CCCOL_RED,
    CCCOL_YELLOW,
    CCCOL_MAGENTA,
    CCCOL_USERDEFINED,
    CCCOL_BLACK,
    CCCOL_TRANSPARENT,
};

enum cc_font {
    CCFONT_REGULAR,
    CCFONT_ITALICS,
    CCFONT_UNDERLINED,
    CCFONT_UNDERLINED_ITALICS,
};

enum cc_charset {
    CCSET_BASIC_AMERICAN,
    CCSET_SPECIAL_AMERICAN,
    CCSET_EXTENDED_SPANISH_FRENCH_MISC,
    CCSET_EXTENDED_PORTUGUESE_GERMAN_DANISH,
};

static const char *charset_overrides[4][128] =
{
    [CCSET_BASIC_AMERICAN] = {
        [0x27] = "\u2019",
        [0x2a] = "\u00e1",
        [0x5c] = "\u00e9",
        [0x5e] = "\u00ed",
        [0x5f] = "\u00f3",
        [0x60] = "\u00fa",
        [0x7b] = "\u00e7",
        [0x7c] = "\u00f7",
        [0x7d] = "\u00d1",
        [0x7e] = "\u00f1",
        [0x7f] = "\u2588"
    },
    [CCSET_SPECIAL_AMERICAN] = {
        [0x30] = "\u00ae",
        [0x31] = "\u00b0",
        [0x32] = "\u00bd",
        [0x33] = "\u00bf",
        [0x34] = "\u2122",
        [0x35] = "\u00a2",
        [0x36] = "\u00a3",
        [0x37] = "\u266a",
        [0x38] = "\u00e0",
        [0x39] = "\u00A0",
        [0x3a] = "\u00e8",
        [0x3b] = "\u00e2",
        [0x3c] = "\u00ea",
        [0x3d] = "\u00ee",
        [0x3e] = "\u00f4",
        [0x3f] = "\u00fb",
    },
    [CCSET_EXTENDED_SPANISH_FRENCH_MISC] = {
        [0x20] = "\u00c1",
        [0x21] = "\u00c9",
        [0x22] = "\u00d3",
        [0x23] = "\u00da",
        [0x24] = "\u00dc",
        [0x25] = "\u00fc",
        [0x26] = "\u00b4",
        [0x27] = "\u00a1",
        [0x28] = "*",
        [0x29] = "\u2018",
        [0x2a] = "-",
        [0x2b] = "\u00a9",
        [0x2c] = "\u2120",
        [0x2d] = "\u00b7",
        [0x2e] = "\u201c",
        [0x2f] = "\u201d",
        [0x30] = "\u00c0",
        [0x31] = "\u00c2",
        [0x32] = "\u00c7",
        [0x33] = "\u00c8",
        [0x34] = "\u00ca",
        [0x35] = "\u00cb",
        [0x36] = "\u00eb",
        [0x37] = "\u00ce",
        [0x38] = "\u00cf",
        [0x39] = "\u00ef",
        [0x3a] = "\u00d4",
        [0x3b] = "\u00d9",
        [0x3c] = "\u00f9",
        [0x3d] = "\u00db",
        [0x3e] = "\u00ab",
        [0x3f] = "\u00bb",
    },
    [CCSET_EXTENDED_PORTUGUESE_GERMAN_DANISH] = {
        [0x20] = "\u00c3",
        [0x21] = "\u00e3",
        [0x22] = "\u00cd",
        [0x23] = "\u00cc",
        [0x24] = "\u00ec",
        [0x25] = "\u00d2",
        [0x26] = "\u00f2",
        [0x27] = "\u00d5",
        [0x28] = "\u00f5",
        [0x29] = "{",
        [0x2a] = "}",
        [0x2b] = "\\",
        [0x2c] = "^",
        [0x2d] = "_",
        [0x2e] = "|",
        [0x2f] = "~",
        [0x30] = "\u00c4",
        [0x31] = "\u00e4",
        [0x32] = "\u00d6",
        [0x33] = "\u00f6",
        [0x34] = "\u00df",
        [0x35] = "\u00a5",
        [0x36] = "\u00a4",
        [0x37] = "\u00a6",
        [0x38] = "\u00c5",
        [0x39] = "\u00e5",
        [0x3a] = "\u00d8",
        [0x3b] = "\u00f8",
        [0x3c] = "\u250c",
        [0x3d] = "\u2510",
        [0x3e] = "\u2514",
        [0x3f] = "\u2518",
    },
};

static const unsigned char bg_attribs[8] = // Color
{
    CCCOL_WHITE,
    CCCOL_GREEN,
    CCCOL_BLUE,
    CCCOL_CYAN,
    CCCOL_RED,
    CCCOL_YELLOW,
    CCCOL_MAGENTA,
    CCCOL_BLACK,
};

static const unsigned char pac2_attribs[32][3] = // Color, font, ident
{
    { CCCOL_WHITE,   CCFONT_REGULAR,            0 },  // 0x40 || 0x60
    { CCCOL_WHITE,   CCFONT_UNDERLINED,         0 },  // 0x41 || 0x61
    { CCCOL_GREEN,   CCFONT_REGULAR,            0 },  // 0x42 || 0x62
    { CCCOL_GREEN,   CCFONT_UNDERLINED,         0 },  // 0x43 || 0x63
    { CCCOL_BLUE,    CCFONT_REGULAR,            0 },  // 0x44 || 0x64
    { CCCOL_BLUE,    CCFONT_UNDERLINED,         0 },  // 0x45 || 0x65
    { CCCOL_CYAN,    CCFONT_REGULAR,            0 },  // 0x46 || 0x66
    { CCCOL_CYAN,    CCFONT_UNDERLINED,         0 },  // 0x47 || 0x67
    { CCCOL_RED,     CCFONT_REGULAR,            0 },  // 0x48 || 0x68
    { CCCOL_RED,     CCFONT_UNDERLINED,         0 },  // 0x49 || 0x69
    { CCCOL_YELLOW,  CCFONT_REGULAR,            0 },  // 0x4a || 0x6a
    { CCCOL_YELLOW,  CCFONT_UNDERLINED,         0 },  // 0x4b || 0x6b
    { CCCOL_MAGENTA, CCFONT_REGULAR,            0 },  // 0x4c || 0x6c
    { CCCOL_MAGENTA, CCFONT_UNDERLINED,         0 },  // 0x4d || 0x6d
    { CCCOL_WHITE,   CCFONT_ITALICS,            0 },  // 0x4e || 0x6e
    { CCCOL_WHITE,   CCFONT_UNDERLINED_ITALICS, 0 },  // 0x4f || 0x6f
    { CCCOL_WHITE,   CCFONT_REGULAR,            0 },  // 0x50 || 0x70
    { CCCOL_WHITE,   CCFONT_UNDERLINED,         0 },  // 0x51 || 0x71
    { CCCOL_WHITE,   CCFONT_REGULAR,            4 },  // 0x52 || 0x72
    { CCCOL_WHITE,   CCFONT_UNDERLINED,         4 },  // 0x53 || 0x73
    { CCCOL_WHITE,   CCFONT_REGULAR,            8 },  // 0x54 || 0x74
    { CCCOL_WHITE,   CCFONT_UNDERLINED,         8 },  // 0x55 || 0x75
    { CCCOL_WHITE,   CCFONT_REGULAR,           12 },  // 0x56 || 0x76
    { CCCOL_WHITE,   CCFONT_UNDERLINED,        12 },  // 0x57 || 0x77
    { CCCOL_WHITE,   CCFONT_REGULAR,           16 },  // 0x58 || 0x78
    { CCCOL_WHITE,   CCFONT_UNDERLINED,        16 },  // 0x59 || 0x79
    { CCCOL_WHITE,   CCFONT_REGULAR,           20 },  // 0x5a || 0x7a
    { CCCOL_WHITE,   CCFONT_UNDERLINED,        20 },  // 0x5b || 0x7b
    { CCCOL_WHITE,   CCFONT_REGULAR,           24 },  // 0x5c || 0x7c
    { CCCOL_WHITE,   CCFONT_UNDERLINED,        24 },  // 0x5d || 0x7d
    { CCCOL_WHITE,   CCFONT_REGULAR,           28 },  // 0x5e || 0x7e
    { CCCOL_WHITE,   CCFONT_UNDERLINED,        28 }   // 0x5f || 0x7f
    /* total 32 entries */
};

struct Screen {
    /* +1 is used to compensate null character of string */
    uint8_t characters[SCREEN_ROWS+1][SCREEN_COLUMNS+1];
    uint8_t charsets[SCREEN_ROWS+1][SCREEN_COLUMNS+1];
    uint8_t colors[SCREEN_ROWS+1][SCREEN_COLUMNS+1];
    uint8_t bgs[SCREEN_ROWS+1][SCREEN_COLUMNS+1];
    uint8_t fonts[SCREEN_ROWS+1][SCREEN_COLUMNS+1];
    /*
     * Bitmask of used rows; if a bit is not set, the
     * corresponding row is not used.
     * for setting row 1  use row | (1 << 0)
     * for setting row 15 use row | (1 << 14)
     */
    int16_t row_used;
};

typedef struct CCaptionSubContext {
    AVClass *class;
    int real_time;
    int real_time_latency_msec;
    int data_field;
    struct Screen screen[2];
    int active_screen;
    uint8_t cursor_row;
    uint8_t cursor_column;
    uint8_t cursor_color;
    uint8_t bg_color;
    uint8_t cursor_font;
    uint8_t cursor_charset;
    AVBPrint buffer[2];
    int buffer_index;
    int buffer_changed;
    int rollup;
    enum cc_mode mode;
    int64_t buffer_time[2];
    int screen_touched;
    int64_t last_real_time;
    uint8_t prev_cmd[2];
    int readorder;
} CCaptionSubContext;

static av_cold int init_decoder(AVCodecContext *avctx)
{
    CCaptionSubContext *ctx = avctx->priv_data;

    av_bprint_init(&ctx->buffer[0], 0, AV_BPRINT_SIZE_UNLIMITED);
    av_bprint_init(&ctx->buffer[1], 0, AV_BPRINT_SIZE_UNLIMITED);
    /* taking by default roll up to 2 */
    ctx->mode = CCMODE_ROLLUP;
    ctx->bg_color = CCCOL_BLACK;
    ctx->rollup = 2;
    ctx->cursor_row = 10;
    return ff_ass_subtitle_header(avctx, "Monospace",
                                 ASS_DEFAULT_FONT_SIZE,
                                 ASS_DEFAULT_COLOR,
                                 ASS_DEFAULT_BACK_COLOR,
                                 ASS_DEFAULT_BOLD,
                                 ASS_DEFAULT_ITALIC,
                                 ASS_DEFAULT_UNDERLINE,
                                 3,
                                 ASS_DEFAULT_ALIGNMENT);
}

static av_cold int close_decoder(AVCodecContext *avctx)
{
    CCaptionSubContext *ctx = avctx->priv_data;
    av_bprint_finalize(&ctx->buffer[0], NULL);
    av_bprint_finalize(&ctx->buffer[1], NULL);
    return 0;
}

static void flush_decoder(AVCodecContext *avctx)
{
    CCaptionSubContext *ctx = avctx->priv_data;
    ctx->screen[0].row_used = 0;
    ctx->screen[1].row_used = 0;
    ctx->prev_cmd[0] = 0;
    ctx->prev_cmd[1] = 0;
    ctx->mode = CCMODE_ROLLUP;
    ctx->rollup = 2;
    ctx->cursor_row = 10;
    ctx->cursor_column = 0;
    ctx->cursor_font = 0;
    ctx->cursor_color = 0;
    ctx->bg_color = CCCOL_BLACK;
    ctx->cursor_charset = 0;
    ctx->active_screen = 0;
    ctx->last_real_time = 0;
    ctx->screen_touched = 0;
    ctx->buffer_changed = 0;
    if (!(avctx->flags2 & AV_CODEC_FLAG2_RO_FLUSH_NOOP))
        ctx->readorder = 0;
    av_bprint_clear(&ctx->buffer[0]);
    av_bprint_clear(&ctx->buffer[1]);
}

/**
 * @param ctx closed caption context just to print log
 */
static void write_char(CCaptionSubContext *ctx, struct Screen *screen, char ch)
{
    uint8_t col = ctx->cursor_column;
    char *row = screen->characters[ctx->cursor_row];
    char *font = screen->fonts[ctx->cursor_row];
    char *color = screen->colors[ctx->cursor_row];
    char *bg = screen->bgs[ctx->cursor_row];
    char *charset = screen->charsets[ctx->cursor_row];

    if (col < SCREEN_COLUMNS) {
        row[col] = ch;
        font[col] = ctx->cursor_font;
        color[col] = ctx->cursor_color;
        bg[col] = ctx->bg_color;
        charset[col] = ctx->cursor_charset;
        ctx->cursor_charset = CCSET_BASIC_AMERICAN;
        if (ch) ctx->cursor_column++;
        return;
    }
    /* We have extra space at end only for null character */
    else if (col == SCREEN_COLUMNS && ch == 0) {
        row[col] = ch;
        return;
    }
    else {
        av_log(ctx, AV_LOG_WARNING, "Data Ignored since exceeding screen width\n");
        return;
    }
}

/**
 * This function after validating parity bit, also remove it from data pair.
 * The first byte doesn't pass parity, we replace it with a solid blank
 * and process the pair.
 * If the second byte doesn't pass parity, it returns INVALIDDATA
 * user can ignore the whole pair and pass the other pair.
 */
static int validate_cc_data_pair(const uint8_t *cc_data_pair, uint8_t *hi)
{
    uint8_t cc_valid = (*cc_data_pair & 4) >>2;
    uint8_t cc_type = *cc_data_pair & 3;

    *hi = cc_data_pair[1];

    if (!cc_valid)
        return AVERROR_INVALIDDATA;

    // if EIA-608 data then verify parity.
    if (cc_type==0 || cc_type==1) {
        if (!av_parity(cc_data_pair[2])) {
            return AVERROR_INVALIDDATA;
        }
        if (!av_parity(cc_data_pair[1])) {
            *hi = 0x7F;
        }
    }

    //Skip non-data
    if ((cc_data_pair[0] == 0xFA || cc_data_pair[0] == 0xFC || cc_data_pair[0] == 0xFD)
         && (cc_data_pair[1] & 0x7F) == 0 && (cc_data_pair[2] & 0x7F) == 0)
        return AVERROR_PATCHWELCOME;

    //skip 708 data
    if (cc_type == 3 || cc_type == 2)
        return AVERROR_PATCHWELCOME;

    return 0;
}

static struct Screen *get_writing_screen(CCaptionSubContext *ctx)
{
    switch (ctx->mode) {
    case CCMODE_POPON:
        // use Inactive screen
        return ctx->screen + !ctx->active_screen;
    case CCMODE_PAINTON:
    case CCMODE_ROLLUP:
    case CCMODE_TEXT:
        // use active screen
        return ctx->screen + ctx->active_screen;
    }
    /* It was never an option */
    return NULL;
}

static void roll_up(CCaptionSubContext *ctx)
{
    struct Screen *screen;
    int i, keep_lines;

    if (ctx->mode == CCMODE_TEXT)
        return;

    screen = get_writing_screen(ctx);

    /* +1 signify cursor_row starts from 0
     * Can't keep lines less then row cursor pos
     */
    keep_lines = FFMIN(ctx->cursor_row + 1, ctx->rollup);

    for (i = 0; i < SCREEN_ROWS; i++) {
        if (i > ctx->cursor_row - keep_lines && i <= ctx->cursor_row)
            continue;
        UNSET_FLAG(screen->row_used, i);
    }

    for (i = 0; i < keep_lines && screen->row_used; i++) {
        const int i_row = ctx->cursor_row - keep_lines + i + 1;

        memcpy(screen->characters[i_row], screen->characters[i_row+1], SCREEN_COLUMNS);
        memcpy(screen->colors[i_row], screen->colors[i_row+1], SCREEN_COLUMNS);
        memcpy(screen->bgs[i_row], screen->bgs[i_row+1], SCREEN_COLUMNS);
        memcpy(screen->fonts[i_row], screen->fonts[i_row+1], SCREEN_COLUMNS);
        memcpy(screen->charsets[i_row], screen->charsets[i_row+1], SCREEN_COLUMNS);
        if (CHECK_FLAG(screen->row_used, i_row + 1))
            SET_FLAG(screen->row_used, i_row);
    }

    UNSET_FLAG(screen->row_used, ctx->cursor_row);
}

static int capture_screen(CCaptionSubContext *ctx)
{
    int i, j, tab = 0;
    struct Screen *screen = ctx->screen + ctx->active_screen;
    enum cc_font prev_font = CCFONT_REGULAR;
    enum cc_color_code prev_color = CCCOL_WHITE;
    enum cc_color_code prev_bg_color = CCCOL_BLACK;
    const int bidx = ctx->buffer_index;

    av_bprint_clear(&ctx->buffer[bidx]);

    for (i = 0; screen->row_used && i < SCREEN_ROWS; i++)
    {
        if (CHECK_FLAG(screen->row_used, i)) {
            const char *row = screen->characters[i];
            const char *charset = screen->charsets[i];
            j = 0;
            while (row[j] == ' ' && charset[j] == CCSET_BASIC_AMERICAN)
                j++;
            if (!tab || j < tab)
                tab = j;
        }
    }

    for (i = 0; screen->row_used && i < SCREEN_ROWS; i++)
    {
        if (CHECK_FLAG(screen->row_used, i)) {
            const char *row = screen->characters[i];
            const char *font = screen->fonts[i];
            const char *bg = screen->bgs[i];
            const char *color = screen->colors[i];
            const char *charset = screen->charsets[i];
            const char *override;
            int x, y, seen_char = 0;
            j = 0;

            /* skip leading space */
            while (row[j] == ' ' && charset[j] == CCSET_BASIC_AMERICAN && j < tab)
                j++;

            x = ASS_DEFAULT_PLAYRESX * (0.1 + 0.0250 * j);
            y = ASS_DEFAULT_PLAYRESY * (0.1 + 0.0533 * i);
            av_bprintf(&ctx->buffer[bidx], "{\\an7}{\\pos(%d,%d)}", x, y);

            for (; j < SCREEN_COLUMNS; j++) {
                const char *e_tag = "", *s_tag = "", *c_tag = "", *b_tag = "";

                if (row[j] == 0)
                    break;

                if (prev_font != font[j]) {
                    switch (prev_font) {
                    case CCFONT_ITALICS:
                        e_tag = "{\\i0}";
                        break;
                    case CCFONT_UNDERLINED:
                        e_tag = "{\\u0}";
                        break;
                    case CCFONT_UNDERLINED_ITALICS:
                        e_tag = "{\\u0}{\\i0}";
                        break;
                    }
                    switch (font[j]) {
                    case CCFONT_ITALICS:
                        s_tag = "{\\i1}";
                        break;
                    case CCFONT_UNDERLINED:
                        s_tag = "{\\u1}";
                        break;
                    case CCFONT_UNDERLINED_ITALICS:
                        s_tag = "{\\u1}{\\i1}";
                        break;
                    }
                }
                if (prev_color != color[j]) {
                    switch (color[j]) {
                    case CCCOL_WHITE:
                        c_tag = "{\\c&HFFFFFF&}";
                        break;
                    case CCCOL_GREEN:
                        c_tag = "{\\c&H00FF00&}";
                        break;
                    case CCCOL_BLUE:
                        c_tag = "{\\c&HFF0000&}";
                        break;
                    case CCCOL_CYAN:
                        c_tag = "{\\c&HFFFF00&}";
                        break;
                    case CCCOL_RED:
                        c_tag = "{\\c&H0000FF&}";
                        break;
                    case CCCOL_YELLOW:
                        c_tag = "{\\c&H00FFFF&}";
                        break;
                    case CCCOL_MAGENTA:
                        c_tag = "{\\c&HFF00FF&}";
                        break;
                    }
                }
                if (prev_bg_color != bg[j]) {
                    switch (bg[j]) {
                    case CCCOL_WHITE:
                        b_tag = "{\\3c&HFFFFFF&}";
                        break;
                    case CCCOL_GREEN:
                        b_tag = "{\\3c&H00FF00&}";
                        break;
                    case CCCOL_BLUE:
                        b_tag = "{\\3c&HFF0000&}";
                        break;
                    case CCCOL_CYAN:
                        b_tag = "{\\3c&HFFFF00&}";
                        break;
                    case CCCOL_RED:
                        b_tag = "{\\3c&H0000FF&}";
                        break;
                    case CCCOL_YELLOW:
                        b_tag = "{\\3c&H00FFFF&}";
                        break;
                    case CCCOL_MAGENTA:
                        b_tag = "{\\3c&HFF00FF&}";
                        break;
                    case CCCOL_BLACK:
                        b_tag = "{\\3c&H000000&}";
                        break;
                    }
                }

                prev_font = font[j];
                prev_color = color[j];
                prev_bg_color = bg[j];
                override = charset_overrides[(int)charset[j]][(int)row[j]];
                if (override) {
                    av_bprintf(&ctx->buffer[bidx], "%s%s%s%s%s", e_tag, s_tag, c_tag, b_tag, override);
                    seen_char = 1;
                } else if (row[j] == ' ' && !seen_char) {
                    av_bprintf(&ctx->buffer[bidx], "%s%s%s%s\\h", e_tag, s_tag, c_tag, b_tag);
                } else {
                    av_bprintf(&ctx->buffer[bidx], "%s%s%s%s%c", e_tag, s_tag, c_tag, b_tag, row[j]);
                    seen_char = 1;
                }

            }
            av_bprintf(&ctx->buffer[bidx], "\\N");
        }
    }
    if (!av_bprint_is_complete(&ctx->buffer[bidx]))
        return AVERROR(ENOMEM);
    if (screen->row_used && ctx->buffer[bidx].len >= 2) {
        ctx->buffer[bidx].len -= 2;
        ctx->buffer[bidx].str[ctx->buffer[bidx].len] = 0;
    }
    ctx->buffer_changed = 1;
    return 0;
}

static void update_time(CCaptionSubContext *ctx, int64_t pts)
{
    ctx->buffer_time[0] = ctx->buffer_time[1];
    ctx->buffer_time[1] = pts;
}

static void handle_bgattr(CCaptionSubContext *ctx, uint8_t hi, uint8_t lo)
{
    const int i = (lo & 0xf) >> 1;

    ctx->bg_color = bg_attribs[i];
}

static void handle_textattr(CCaptionSubContext *ctx, uint8_t hi, uint8_t lo)
{
    int i = lo - 0x20;
    struct Screen *screen = get_writing_screen(ctx);

    if (i >= 32)
        return;

    ctx->cursor_color = pac2_attribs[i][0];
    ctx->cursor_font = pac2_attribs[i][1];

    SET_FLAG(screen->row_used, ctx->cursor_row);
    write_char(ctx, screen, ' ');
}

static void handle_pac(CCaptionSubContext *ctx, uint8_t hi, uint8_t lo)
{
    static const int8_t row_map[] = {
        11, -1, 1, 2, 3, 4, 12, 13, 14, 15, 5, 6, 7, 8, 9, 10
    };
    const int index = ( (hi<<1) & 0x0e) | ( (lo>>5) & 0x01 );
    struct Screen *screen = get_writing_screen(ctx);
    int indent, i;

    if (row_map[index] <= 0) {
        av_log(ctx, AV_LOG_DEBUG, "Invalid pac index encountered\n");
        return;
    }

    lo &= 0x1f;

    ctx->cursor_row = row_map[index] - 1;
    ctx->cursor_color =  pac2_attribs[lo][0];
    ctx->cursor_font = pac2_attribs[lo][1];
    ctx->cursor_charset = CCSET_BASIC_AMERICAN;
    ctx->cursor_column = 0;
    indent = pac2_attribs[lo][2];
    for (i = 0; i < indent; i++) {
        write_char(ctx, screen, ' ');
    }
}

static int handle_edm(CCaptionSubContext *ctx)
{
    struct Screen *screen = ctx->screen + ctx->active_screen;
    int ret;

    // In buffered mode, keep writing to screen until it is wiped.
    // Before wiping the display, capture contents to emit subtitle.
    if (!ctx->real_time)
        ret = capture_screen(ctx);

    screen->row_used = 0;
    ctx->bg_color = CCCOL_BLACK;

    // In realtime mode, emit an empty caption so the last one doesn't
    // stay on the screen.
    if (ctx->real_time)
        ret = capture_screen(ctx);

    return ret;
}

static int handle_eoc(CCaptionSubContext *ctx)
{
    int ret;

    ctx->active_screen = !ctx->active_screen;

    // In buffered mode, we wait til the *next* EOC and
    // capture what was already on the screen since the last EOC.
    if (!ctx->real_time)
        ret = handle_edm(ctx);

    ctx->cursor_column = 0;

    // In realtime mode, we display the buffered contents (after
    // flipping the buffer to active above) as soon as EOC arrives.
    if (ctx->real_time)
        ret = capture_screen(ctx);

    return ret;
}

static void handle_delete_end_of_row(CCaptionSubContext *ctx)
{
    struct Screen *screen = get_writing_screen(ctx);
    write_char(ctx, screen, 0);
}

static void handle_char(CCaptionSubContext *ctx, char hi, char lo)
{
    struct Screen *screen = get_writing_screen(ctx);

    SET_FLAG(screen->row_used, ctx->cursor_row);

    switch (hi) {
      case 0x11:
        ctx->cursor_charset = CCSET_SPECIAL_AMERICAN;
        break;
      case 0x12:
        if (ctx->cursor_column > 0)
            ctx->cursor_column -= 1;
        ctx->cursor_charset = CCSET_EXTENDED_SPANISH_FRENCH_MISC;
        break;
      case 0x13:
        if (ctx->cursor_column > 0)
            ctx->cursor_column -= 1;
        ctx->cursor_charset = CCSET_EXTENDED_PORTUGUESE_GERMAN_DANISH;
        break;
      default:
        ctx->cursor_charset = CCSET_BASIC_AMERICAN;
        write_char(ctx, screen, hi);
        break;
    }

    if (lo) {
        write_char(ctx, screen, lo);
    }
    write_char(ctx, screen, 0);

    if (ctx->mode != CCMODE_POPON)
        ctx->screen_touched = 1;

    if (lo)
       ff_dlog(ctx, "(%c,%c)\n", hi, lo);
    else
       ff_dlog(ctx, "(%c)\n", hi);
}

static int process_cc608(CCaptionSubContext *ctx, uint8_t hi, uint8_t lo)
{
    int ret = 0;

    if (hi == ctx->prev_cmd[0] && lo == ctx->prev_cmd[1]) {
        return 0;
    }

    /* set prev command */
    ctx->prev_cmd[0] = hi;
    ctx->prev_cmd[1] = lo;

    if ( (hi == 0x10 && (lo >= 0x40 && lo <= 0x5f)) ||
       ( (hi >= 0x11 && hi <= 0x17) && (lo >= 0x40 && lo <= 0x7f) ) ) {
        handle_pac(ctx, hi, lo);
    } else if ( ( hi == 0x11 && lo >= 0x20 && lo <= 0x2f ) ||
                ( hi == 0x17 && lo >= 0x2e && lo <= 0x2f) ) {
        handle_textattr(ctx, hi, lo);
    } else if ((hi == 0x10 && lo >= 0x20 && lo <= 0x2f)) {
        handle_bgattr(ctx, hi, lo);
    } else if (hi == 0x14 || hi == 0x15 || hi == 0x1c) {
        switch (lo) {
        case 0x20:
            /* resume caption loading */
            ctx->mode = CCMODE_POPON;
            break;
        case 0x24:
            handle_delete_end_of_row(ctx);
            break;
        case 0x25:
        case 0x26:
        case 0x27:
            ctx->rollup = lo - 0x23;
            ctx->mode = CCMODE_ROLLUP;
            break;
        case 0x29:
            /* resume direct captioning */
            ctx->mode = CCMODE_PAINTON;
            break;
        case 0x2b:
            /* resume text display */
            ctx->mode = CCMODE_TEXT;
            break;
        case 0x2c:
            /* erase display memory */
            handle_edm(ctx);
            break;
        case 0x2d:
            /* carriage return */
            ff_dlog(ctx, "carriage return\n");
            if (!ctx->real_time)
                ret = capture_screen(ctx);
            roll_up(ctx);
            ctx->cursor_column = 0;
            break;
        case 0x2e:
            /* erase buffered (non displayed) memory */
            // Only in realtime mode. In buffered mode, we re-use the inactive screen
            // for our own buffering.
            if (ctx->real_time) {
                struct Screen *screen = ctx->screen + !ctx->active_screen;
                screen->row_used = 0;
            }
            break;
        case 0x2f:
            /* end of caption */
            ff_dlog(ctx, "handle_eoc\n");
            ret = handle_eoc(ctx);
            break;
        default:
            ff_dlog(ctx, "Unknown command 0x%hhx 0x%hhx\n", hi, lo);
            break;
        }
    } else if (hi >= 0x11 && hi <= 0x13) {
        /* Special characters */
        handle_char(ctx, hi, lo);
    } else if (hi >= 0x20) {
        /* Standard characters (always in pairs) */
        handle_char(ctx, hi, lo);
        ctx->prev_cmd[0] = ctx->prev_cmd[1] = 0;
    } else if (hi == 0x17 && lo >= 0x21 && lo <= 0x23) {
        int i;
        /* Tab offsets (spacing) */
        for (i = 0; i < lo - 0x20; i++) {
            handle_char(ctx, ' ', 0);
        }
    } else {
        /* Ignoring all other non data code */
        ff_dlog(ctx, "Unknown command 0x%hhx 0x%hhx\n", hi, lo);
    }

    return ret;
}

static int decode(AVCodecContext *avctx, AVSubtitle *sub,
                  int *got_sub, const AVPacket *avpkt)
{
    CCaptionSubContext *ctx = avctx->priv_data;
    int64_t in_time = sub->pts;
    int64_t start_time;
    int64_t end_time;
    int bidx = ctx->buffer_index;
    const uint8_t *bptr = avpkt->data;
    int len = avpkt->size;
    int ret = 0;
    int i;
    unsigned nb_rect_allocated = 0;

    for (i = 0; i < len; i += 3) {
        uint8_t hi, cc_type = bptr[i] & 1;

        if (ctx->data_field < 0)
            ctx->data_field = cc_type;

        if (validate_cc_data_pair(bptr + i, &hi))
            continue;

        if (cc_type != ctx->data_field)
            continue;

        ret = process_cc608(ctx, hi & 0x7f, bptr[i + 2] & 0x7f);
        if (ret < 0)
            return ret;

        if (!ctx->buffer_changed)
            continue;
        ctx->buffer_changed = 0;

        if (!ctx->real_time && ctx->mode == CCMODE_POPON)
            ctx->buffer_index = bidx = !ctx->buffer_index;

        update_time(ctx, in_time);

        if (ctx->buffer[bidx].str[0] || ctx->real_time) {
            ff_dlog(ctx, "cdp writing data (%s)\n", ctx->buffer[bidx].str);
            start_time = ctx->buffer_time[0];
            sub->pts = start_time;
            end_time = ctx->buffer_time[1];
            if (!ctx->real_time)
                sub->end_display_time = av_rescale_q(end_time - start_time,
                                                     AV_TIME_BASE_Q, ms_tb);
            else
                sub->end_display_time = -1;
            ret = ff_ass_add_rect2(sub, ctx->buffer[bidx].str, ctx->readorder++, 0, NULL, NULL, &nb_rect_allocated);
            if (ret < 0)
                return ret;
            ctx->last_real_time = sub->pts;
            ctx->screen_touched = 0;
        }
    }

    if (!bptr && !ctx->real_time && ctx->buffer[!ctx->buffer_index].str[0]) {
        bidx = !ctx->buffer_index;
        ret = ff_ass_add_rect2(sub, ctx->buffer[bidx].str, ctx->readorder++, 0, NULL, NULL, &nb_rect_allocated);
        if (ret < 0)
            return ret;
        av_bprint_clear(&ctx->buffer[bidx]);
        sub->pts = ctx->buffer_time[1];
        sub->end_display_time = av_rescale_q(ctx->buffer_time[1] - ctx->buffer_time[0],
                                             AV_TIME_BASE_Q, ms_tb);
        if (sub->end_display_time == 0)
            sub->end_display_time = ctx->buffer[bidx].len * 20;
    }

    if (ctx->real_time && ctx->screen_touched &&
        sub->pts >= ctx->last_real_time + av_rescale_q(ctx->real_time_latency_msec, ms_tb, AV_TIME_BASE_Q)) {
        ctx->last_real_time = sub->pts;
        ctx->screen_touched = 0;

        capture_screen(ctx);
        ctx->buffer_changed = 0;

        ret = ff_ass_add_rect2(sub, ctx->buffer[bidx].str, ctx->readorder++, 0, NULL, NULL, &nb_rect_allocated);
        if (ret < 0)
            return ret;
        sub->end_display_time = -1;
    }

    *got_sub = sub->num_rects > 0;
    return avpkt->size;
}

#define OFFSET(x) offsetof(CCaptionSubContext, x)
#define SD AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM
static const AVOption options[] = {
    { "real_time", "emit subtitle events as they are decoded for real-time display", OFFSET(real_time), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, SD },
    { "real_time_latency_msec", "minimum elapsed time between emitting real-time subtitle events", OFFSET(real_time_latency_msec), AV_OPT_TYPE_INT, { .i64 = 200 }, 0, 500, SD },
    { "data_field", "select data field", OFFSET(data_field), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 1, SD, "data_field" },
    { "auto",   "pick first one that appears", 0, AV_OPT_TYPE_CONST, { .i64 =-1 }, 0, 0, SD, "data_field" },
    { "first",  NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 0 }, 0, 0, SD, "data_field" },
    { "second", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 1 }, 0, 0, SD, "data_field" },
    {NULL}
};

static const AVClass ccaption_dec_class = {
    .class_name = "Closed caption Decoder",
    .item_name  = av_default_item_name,
    .option     = options,
    .version    = LIBAVUTIL_VERSION_INT,
};

const FFCodec ff_ccaption_decoder = {
    .p.name         = "cc_dec",
    CODEC_LONG_NAME("Closed Caption (EIA-608 / CEA-708)"),
    .p.type         = AVMEDIA_TYPE_SUBTITLE,
    .p.id           = AV_CODEC_ID_EIA_608,
    .p.priv_class   = &ccaption_dec_class,
    .p.capabilities = AV_CODEC_CAP_DELAY,
    .priv_data_size = sizeof(CCaptionSubContext),
    .init           = init_decoder,
    .close          = close_decoder,
    .flush          = flush_decoder,
    FF_CODEC_DECODE_SUB_CB(decode),
};