aboutsummaryrefslogtreecommitdiffstats
path: root/libavcodec/movtextdec.c
blob: f799252bf212938506f940a58c726dff169fa8fb (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
/*
 * 3GPP TS 26.245 Timed Text decoder
 * Copyright (c) 2012  Philip Langdale <philipl@overt.org>
 *
 * 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 "libavutil/opt.h"
#include "libavutil/avstring.h"
#include "libavutil/common.h"
#include "libavutil/bprint.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/mem.h"
#include "bytestream.h"
#include "codec_internal.h"

#define STYLE_FLAG_BOLD         (1<<0)
#define STYLE_FLAG_ITALIC       (1<<1)
#define STYLE_FLAG_UNDERLINE    (1<<2)

#define BOX_SIZE_INITIAL    40

#define STYL_BOX   (1<<0)
#define HLIT_BOX   (1<<1)
#define HCLR_BOX   (1<<2)
#define TWRP_BOX   (1<<3)

#define BOTTOM_LEFT     1
#define BOTTOM_CENTER   2
#define BOTTOM_RIGHT    3
#define MIDDLE_LEFT     4
#define MIDDLE_CENTER   5
#define MIDDLE_RIGHT    6
#define TOP_LEFT        7
#define TOP_CENTER      8
#define TOP_RIGHT       9

#define RGB_TO_BGR(c) (((c) & 0xff) << 16 | ((c) & 0xff00) | (((c) >> 16) & 0xff))

typedef struct {
    uint16_t font_id;
    char *font;
} FontRecord;

typedef struct {
    uint16_t start;
    uint16_t end;
    uint8_t flags;
    uint8_t bold;
    uint8_t italic;
    uint8_t underline;
    int color;
    uint8_t alpha;
    uint8_t fontsize;
    uint16_t font_id;
} StyleBox;

typedef struct {
    StyleBox style;
    const char *font;
    int back_color;
    uint8_t back_alpha;
    int alignment;
} MovTextDefault;

typedef struct {
    uint16_t hlit_start;
    uint16_t hlit_end;
} HighlightBox;

typedef struct {
   uint8_t hlit_color[4];
} HilightcolorBox;

typedef struct {
    uint8_t wrap_flag;
} TextWrapBox;

typedef struct {
    AVClass *class;
    StyleBox *s;
    HighlightBox h;
    HilightcolorBox c;
    FontRecord *ftab;
    TextWrapBox w;
    MovTextDefault d;
    uint8_t box_flags;
    uint16_t style_entries, ftab_entries;
    int readorder;
    int frame_width;
    int frame_height;
} MovTextContext;

typedef struct {
    uint32_t type;
    unsigned base_size;
    int (*decode)(const uint8_t *tsmb, MovTextContext *m, uint64_t size);
} Box;

static void mov_text_cleanup(MovTextContext *m)
{
    if (m->box_flags & STYL_BOX) {
        av_freep(&m->s);
        m->style_entries = 0;
    }
}

static void mov_text_cleanup_ftab(MovTextContext *m)
{
    for (unsigned i = 0; i < m->ftab_entries; i++)
        av_freep(&m->ftab[i].font);
    av_freep(&m->ftab);
    m->ftab_entries = 0;
}

static void mov_text_parse_style_record(StyleBox *style, const uint8_t **ptr)
{
    // fontID
    style->font_id   = bytestream_get_be16(ptr);
    // face-style-flags
    style->flags     = bytestream_get_byte(ptr);
    style->bold      = !!(style->flags & STYLE_FLAG_BOLD);
    style->italic    = !!(style->flags & STYLE_FLAG_ITALIC);
    style->underline = !!(style->flags & STYLE_FLAG_UNDERLINE);
    // fontsize
    style->fontsize  = bytestream_get_byte(ptr);
    // Primary color
    style->color     = bytestream_get_be24(ptr);
    style->color     = RGB_TO_BGR(style->color);
    style->alpha     = bytestream_get_byte(ptr);
}

static int mov_text_tx3g(AVCodecContext *avctx, MovTextContext *m)
{
    const uint8_t *tx3g_ptr = avctx->extradata;
    int i, j = -1, font_length, remaining = avctx->extradata_size - BOX_SIZE_INITIAL;
    int8_t v_align, h_align;
    unsigned ftab_entries;

    m->ftab_entries = 0;
    if (remaining < 0)
        return -1;

    // Display Flags
    tx3g_ptr += 4;
    // Alignment
    h_align = bytestream_get_byte(&tx3g_ptr);
    v_align = bytestream_get_byte(&tx3g_ptr);
    if (h_align == 0) {
        if (v_align == 0)
            m->d.alignment = TOP_LEFT;
        if (v_align == 1)
            m->d.alignment = MIDDLE_LEFT;
        if (v_align == -1)
            m->d.alignment = BOTTOM_LEFT;
    }
    if (h_align == 1) {
        if (v_align == 0)
            m->d.alignment = TOP_CENTER;
        if (v_align == 1)
            m->d.alignment = MIDDLE_CENTER;
        if (v_align == -1)
            m->d.alignment = BOTTOM_CENTER;
    }
    if (h_align == -1) {
        if (v_align == 0)
            m->d.alignment = TOP_RIGHT;
        if (v_align == 1)
            m->d.alignment = MIDDLE_RIGHT;
        if (v_align == -1)
            m->d.alignment = BOTTOM_RIGHT;
    }
    // Background Color
    m->d.back_color = bytestream_get_be24(&tx3g_ptr);
    m->d.back_color = RGB_TO_BGR(m->d.back_color);
    m->d.back_alpha = bytestream_get_byte(&tx3g_ptr);
    // BoxRecord
    tx3g_ptr += 8;
    // StyleRecord
    tx3g_ptr += 4;
    mov_text_parse_style_record(&m->d.style, &tx3g_ptr);
    // FontRecord
    // FontRecord Size
    tx3g_ptr += 4;
    // ftab
    tx3g_ptr += 4;

    // In case of broken header, init default font
    m->d.font = ASS_DEFAULT_FONT;

    ftab_entries = bytestream_get_be16(&tx3g_ptr);
    if (!ftab_entries)
        return 0;
    remaining   -= 3 * ftab_entries;
    if (remaining < 0)
        return AVERROR_INVALIDDATA;
    m->ftab = av_calloc(ftab_entries, sizeof(*m->ftab));
    if (!m->ftab)
        return AVERROR(ENOMEM);
    m->ftab_entries = ftab_entries;

    for (i = 0; i < m->ftab_entries; i++) {
        m->ftab[i].font_id = bytestream_get_be16(&tx3g_ptr);
        if (m->ftab[i].font_id == m->d.style.font_id)
            j = i;
        font_length = bytestream_get_byte(&tx3g_ptr);

        remaining  -= font_length;
        if (remaining < 0) {
            mov_text_cleanup_ftab(m);
            return -1;
        }
        m->ftab[i].font = av_malloc(font_length + 1);
        if (!m->ftab[i].font) {
            mov_text_cleanup_ftab(m);
            return AVERROR(ENOMEM);
        }
        bytestream_get_buffer(&tx3g_ptr, m->ftab[i].font, font_length);
        m->ftab[i].font[font_length] = '\0';
    }
    if (j >= 0)
        m->d.font = m->ftab[j].font;
    return 0;
}

static int decode_twrp(const uint8_t *tsmb, MovTextContext *m, uint64_t size)
{
    m->box_flags |= TWRP_BOX;
    m->w.wrap_flag = bytestream_get_byte(&tsmb);
    return 0;
}

static int decode_hlit(const uint8_t *tsmb, MovTextContext *m, uint64_t size)
{
    m->box_flags |= HLIT_BOX;
    m->h.hlit_start = bytestream_get_be16(&tsmb);
    m->h.hlit_end   = bytestream_get_be16(&tsmb);
    return 0;
}

static int decode_hclr(const uint8_t *tsmb, MovTextContext *m, uint64_t size)
{
    m->box_flags |= HCLR_BOX;
    bytestream_get_buffer(&tsmb, m->c.hlit_color, 4);
    return 0;
}

static int styles_equivalent(const StyleBox *a, const StyleBox *b)
{
#define CMP(field) ((a)->field == (b)->field)
    return CMP(bold)  && CMP(italic)   && CMP(underline) && CMP(color) &&
           CMP(alpha) && CMP(fontsize) && CMP(font_id);
#undef CMP
}

static int decode_styl(const uint8_t *tsmb, MovTextContext *m, uint64_t size)
{
    int i;
    int style_entries = bytestream_get_be16(&tsmb);
    StyleBox *tmp;

    // A single style record is of length 12 bytes.
    if (2 + style_entries * 12 > size)
        return -1;

    tmp = av_realloc_array(m->s, style_entries, sizeof(*m->s));
    if (!tmp)
        return AVERROR(ENOMEM);
    m->s             = tmp;
    m->style_entries = style_entries;

    m->box_flags |= STYL_BOX;
    for(i = 0; i < m->style_entries; i++) {
        StyleBox *style = &m->s[i];

        style->start = bytestream_get_be16(&tsmb);
        style->end   = bytestream_get_be16(&tsmb);
        if (style->end < style->start ||
            (i && style->start < m->s[i - 1].end)) {
            mov_text_cleanup(m);
            return AVERROR_INVALIDDATA;
        }
        if (style->start == style->end) {
            /* Skip this style as it applies to no character */
            tsmb += 8;
            m->style_entries--;
            i--;
            continue;
        }

        mov_text_parse_style_record(style, &tsmb);
        if (styles_equivalent(style, &m->d.style)) {
            /* Skip this style as it is equivalent to the default style */
            m->style_entries--;
            i--;
            continue;
        } else if (i && style->start == style[-1].end &&
                   styles_equivalent(style, &style[-1])) {
            /* Merge the two adjacent styles */
            style[-1].end = style->end;
            m->style_entries--;
            i--;
            continue;
        }
    }
    return 0;
}

static const Box box_types[] = {
    { MKBETAG('s','t','y','l'), 2, decode_styl },
    { MKBETAG('h','l','i','t'), 4, decode_hlit },
    { MKBETAG('h','c','l','r'), 4, decode_hclr },
    { MKBETAG('t','w','r','p'), 1, decode_twrp }
};

const static size_t box_count = FF_ARRAY_ELEMS(box_types);

// Return byte length of the UTF-8 sequence starting at text[0]. 0 on error.
static int get_utf8_length_at(const char *text, const char *text_end)
{
    const char *start = text;
    int err = 0;
    uint32_t c;
    GET_UTF8(c, text < text_end ? (uint8_t)*text++ : (err = 1, 0), goto error;);
    if (err)
        goto error;
    return text - start;
error:
    return 0;
}

static int text_to_ass(AVBPrint *buf, const char *text, const char *text_end,
                       AVCodecContext *avctx)
{
    MovTextContext *m = avctx->priv_data;
    const StyleBox *const default_style = &m->d.style;
    int i = 0;
    int text_pos = 0;
    int entry = 0;
    int color = default_style->color;

    if (text < text_end && m->box_flags & TWRP_BOX) {
        if (m->w.wrap_flag == 1) {
            av_bprintf(buf, "{\\q1}"); /* End of line wrap */
        } else {
            av_bprintf(buf, "{\\q2}"); /* No wrap */
        }
    }

    while (text < text_end) {
        int len;

        if ((m->box_flags & STYL_BOX) && entry < m->style_entries) {
            const StyleBox *style = &m->s[entry];
            if (text_pos == style->end) {
                av_bprintf(buf, "{\\r}");
                color = default_style->color;
                entry++;
                style++;
            }
            if (entry < m->style_entries && text_pos == style->start) {
                if (style->bold ^ default_style->bold)
                    av_bprintf(buf, "{\\b%d}", style->bold);
                if (style->italic ^ default_style->italic)
                    av_bprintf(buf, "{\\i%d}", style->italic);
                if (style->underline ^ default_style->underline)
                    av_bprintf(buf, "{\\u%d}", style->underline);
                if (style->fontsize != default_style->fontsize)
                    av_bprintf(buf, "{\\fs%d}", style->fontsize);
                if (style->font_id != default_style->font_id)
                    for (i = 0; i < m->ftab_entries; i++) {
                        if (style->font_id == m->ftab[i].font_id)
                            av_bprintf(buf, "{\\fn%s}", m->ftab[i].font);
                    }
                if (default_style->color != style->color) {
                    color = style->color;
                    av_bprintf(buf, "{\\1c&H%X&}", color);
                }
                if (default_style->alpha != style->alpha)
                    av_bprintf(buf, "{\\1a&H%02X&}", 255 - style->alpha);
            }
        }
        if (m->box_flags & HLIT_BOX) {
            if (text_pos == m->h.hlit_start) {
                /* If hclr box is present, set the secondary color to the color
                 * specified. Otherwise, set primary color to white and secondary
                 * color to black. These colors will come from TextSampleModifier
                 * boxes in future and inverse video technique for highlight will
                 * be implemented.
                 */
                if (m->box_flags & HCLR_BOX) {
                    av_bprintf(buf, "{\\2c&H%02x%02x%02x&}", m->c.hlit_color[2],
                                m->c.hlit_color[1], m->c.hlit_color[0]);
                } else {
                    av_bprintf(buf, "{\\1c&H000000&}{\\2c&HFFFFFF&}");
                }
            }
            if (text_pos == m->h.hlit_end) {
                if (m->box_flags & HCLR_BOX) {
                    av_bprintf(buf, "{\\2c&H%X&}", default_style->color);
                } else {
                    av_bprintf(buf, "{\\1c&H%X&}{\\2c&H%X&}",
                               color, default_style->color);
                }
            }
        }

        len = get_utf8_length_at(text, text_end);
        if (len < 1) {
            av_log(avctx, AV_LOG_ERROR, "invalid UTF-8 byte in subtitle\n");
            len = 1;
        }
        switch (*text) {
        case '\r':
            break;
        case '\n':
            av_bprintf(buf, "\\N");
            break;
        default:
            av_bprint_append_data(buf, text, len);
            break;
        }
        text += len;
        text_pos++;
    }

    return 0;
}

static int mov_text_init(AVCodecContext *avctx) {
    /*
     * TODO: Handle the default text style.
     * NB: Most players ignore styles completely, with the result that
     * it's very common to find files where the default style is broken
     * and respecting it results in a worse experience than ignoring it.
     */
    int ret;
    MovTextContext *m = avctx->priv_data;
    ret = mov_text_tx3g(avctx, m);
    if (ret == 0) {
        const StyleBox *const default_style = &m->d.style;
        if (!m->frame_width || !m->frame_height) {
            m->frame_width = ASS_DEFAULT_PLAYRESX;
            m->frame_height = ASS_DEFAULT_PLAYRESY;
        }
        return ff_ass_subtitle_header_full(avctx,
                    m->frame_width, m->frame_height,
                    m->d.font, default_style->fontsize,
                    (255U - default_style->alpha) << 24 | default_style->color,
                    (255U - default_style->alpha) << 24 | default_style->color,
                    (255U - m->d.back_alpha) << 24 | m->d.back_color,
                    (255U - m->d.back_alpha) << 24 | m->d.back_color,
                    default_style->bold, default_style->italic, default_style->underline,
                    ASS_DEFAULT_BORDERSTYLE, m->d.alignment);
    } else
        return ff_ass_subtitle_header_default(avctx);
}

static int mov_text_decode_frame(AVCodecContext *avctx, AVSubtitle *sub,
                                 int *got_sub_ptr, const AVPacket *avpkt)
{
    MovTextContext *m = avctx->priv_data;
    int ret;
    AVBPrint buf;
    const char *ptr = avpkt->data, *end;
    int text_length;
    size_t i;

    if (!ptr || avpkt->size < 2)
        return AVERROR_INVALIDDATA;

    /*
     * A packet of size two with value zero is an empty subtitle
     * used to mark the end of the previous non-empty subtitle.
     * We can just drop them here as we have duration information
     * already. If the value is non-zero, then it's technically a
     * bad packet.
     */
    if (avpkt->size == 2)
        return AV_RB16(ptr) == 0 ? 0 : AVERROR_INVALIDDATA;

    /*
     * The first two bytes of the packet are the length of the text string
     * In complex cases, there are style descriptors appended to the string
     * so we can't just assume the packet size is the string size.
     */
    text_length = AV_RB16(ptr);
    end = ptr + FFMIN(2 + text_length, avpkt->size);
    ptr += 2;

    mov_text_cleanup(m);

    m->style_entries = 0;
    m->box_flags = 0;
    // Note that the spec recommends lines be no longer than 2048 characters.
    av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
    if (text_length + 2 < avpkt->size) {
        const uint8_t *tsmb = end;
        const uint8_t *const tsmb_end = avpkt->data + avpkt->size;
        // A box is a minimum of 8 bytes.
        while (tsmb_end - tsmb >= 8) {
            uint64_t tsmb_size = bytestream_get_be32(&tsmb);
            uint32_t tsmb_type = bytestream_get_be32(&tsmb);
            int size_var, ret_tsmb;

            if (tsmb_size == 1) {
                if (tsmb_end - tsmb < 8)
                    break;
                tsmb_size = bytestream_get_be64(&tsmb);
                size_var = 16;
            } else
                size_var = 8;
            //size_var is equal to 8 or 16 depending on the size of box

            if (tsmb_size < size_var) {
                av_log(avctx, AV_LOG_ERROR, "tsmb_size invalid\n");
                return AVERROR_INVALIDDATA;
            }
            tsmb_size -= size_var;

            if (tsmb_end - tsmb < tsmb_size)
                break;

            for (i = 0; i < box_count; i++) {
                if (tsmb_type == box_types[i].type) {
                    if (tsmb_size < box_types[i].base_size)
                        break;
                    ret_tsmb = box_types[i].decode(tsmb, m, tsmb_size);
                    if (ret_tsmb == -1)
                        break;
                }
            }
            tsmb += tsmb_size;
        }
        text_to_ass(&buf, ptr, end, avctx);
        mov_text_cleanup(m);
    } else
        text_to_ass(&buf, ptr, end, avctx);

    ret = ff_ass_add_rect(sub, buf.str, m->readorder++, 0, NULL, NULL);
    av_bprint_finalize(&buf, NULL);
    if (ret < 0)
        return ret;
    *got_sub_ptr = sub->num_rects > 0;
    return avpkt->size;
}

static int mov_text_decode_close(AVCodecContext *avctx)
{
    MovTextContext *m = avctx->priv_data;
    mov_text_cleanup_ftab(m);
    mov_text_cleanup(m);
    return 0;
}

static void mov_text_flush(AVCodecContext *avctx)
{
    MovTextContext *m = avctx->priv_data;
    if (!(avctx->flags2 & AV_CODEC_FLAG2_RO_FLUSH_NOOP))
        m->readorder = 0;
}

#define OFFSET(x) offsetof(MovTextContext, x)
#define FLAGS AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_SUBTITLE_PARAM
static const AVOption options[] = {
    { "width", "Frame width, usually video width", OFFSET(frame_width), AV_OPT_TYPE_INT, {.i64=0}, 0, INT_MAX, FLAGS },
    { "height", "Frame height, usually video height", OFFSET(frame_height), AV_OPT_TYPE_INT, {.i64=0}, 0, INT_MAX, FLAGS },
    { NULL },
};

static const AVClass mov_text_decoder_class = {
    .class_name = "MOV text decoder",
    .item_name  = av_default_item_name,
    .option     = options,
    .version    = LIBAVUTIL_VERSION_INT,
};

const FFCodec ff_movtext_decoder = {
    .p.name       = "mov_text",
    CODEC_LONG_NAME("3GPP Timed Text subtitle"),
    .p.type       = AVMEDIA_TYPE_SUBTITLE,
    .p.id         = AV_CODEC_ID_MOV_TEXT,
    .priv_data_size = sizeof(MovTextContext),
    .p.priv_class = &mov_text_decoder_class,
    .init         = mov_text_init,
    FF_CODEC_DECODE_SUB_CB(mov_text_decode_frame),
    .close        = mov_text_decode_close,
    .flush        = mov_text_flush,
};