summaryrefslogtreecommitdiffstats
path: root/libhb/decssasub.c
blob: 39d051902aa4bb3ef3567c3dfdda0eb0bebc826a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
/* decssasub.c

   Copyright (c) 2003-2018 HandBrake Team
   This file is part of the HandBrake source code
   Homepage: <http://handbrake.fr/>.
   It may be used under the terms of the GNU General Public License v2.
   For full terms see the file COPYING file or visit http://www.gnu.org/licenses/gpl-2.0.html
 */

/*
 * Converts SSA subtitles to either:
 * (1) TEXTSUB format: UTF-8 subtitles with limited HTML-style markup (<b>, <i>, <u>), or
 * (2) PICTURESUB format, using libass.
 *
 * SSA format references:
 *   http://www.matroska.org/technical/specs/subtitles/ssa.html
 *   http://moodub.free.fr/video/ass-specs.doc
 *   vlc-1.0.4/modules/codec/subtitles/subsass.c:ParseSSAString
 *
 * libass references:
 *   libass-0.9.9/ass.h
 *   vlc-1.0.4/modules/codec/libass.c
 *
 * @author David Foster (davidfstr)
 */
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include "hb.h"

#include <ass/ass.h>
#include "decssasub.h"
#include "colormap.h"

struct hb_work_private_s
{
    // If decoding to PICTURESUB format:
    int readOrder;

    hb_job_t *job;
};

#define SSA_2_HB_TIME(hr,min,sec,centi) \
    ( 90LL * ( hr    * 1000LL * 60 * 60 +\
              min   * 1000LL * 60 +\
              sec   * 1000LL +\
              centi * 10LL ) )

#define SSA_VERBOSE_PACKETS 0

static int ssa_update_style(char *ssa, hb_subtitle_style_t *style)
{
    int pos, end, index;

    if (ssa[0] != '{')
        return 0;

    pos = 1;
    while (ssa[pos] != '}' && ssa[pos] != '\0')
    {
        index = -1;

        // Skip any malformed markup junk
        while (strchr("\\}", ssa[pos]) == NULL) pos++;
        pos++;
        // Check for an index that is in some markup (e.g. font color)
        if (isdigit(ssa[pos]))
        {
            index = ssa[pos++] - 0x30;
        }
        // Find the end of this markup clause
        end = pos;
        while (strchr("\\}", ssa[end]) == NULL) end++;
        // Handle simple integer valued attributes
        if (strchr("ibu", ssa[pos]) != NULL && isdigit(ssa[pos+1]))
        {
            int val = strtol(ssa + pos + 1, NULL, 0);
            switch (ssa[pos])
            {
                case 'i':
                    style->flags = (style->flags & ~HB_STYLE_FLAG_ITALIC) |
                                   !!val * HB_STYLE_FLAG_ITALIC;
                    break;
                case 'b':
                    style->flags = (style->flags & ~HB_STYLE_FLAG_BOLD) |
                                   !!val * HB_STYLE_FLAG_BOLD;
                    break;
                case 'u':
                    style->flags = (style->flags & ~HB_STYLE_FLAG_UNDERLINE) |
                                   !!val * HB_STYLE_FLAG_UNDERLINE;
                    break;
            }
        }
        if (ssa[pos] == 'c' && ssa[pos+1] == '&' && ssa[pos+2] == 'H')
        {
            // Font color markup
            char *endptr;
            uint32_t bgr;

            bgr = strtol(ssa + pos + 3, &endptr, 16);
            if (*endptr == '&')
            {
                switch (index)
                {
                    case -1:
                    case 1:
                        style->fg_rgb = HB_BGR_TO_RGB(bgr);
                        break;
                    case 2:
                        style->alt_rgb = HB_BGR_TO_RGB(bgr);
                        break;
                    case 3:
                        style->ol_rgb = HB_BGR_TO_RGB(bgr);
                        break;
                    case 4:
                        style->bg_rgb = HB_BGR_TO_RGB(bgr);
                        break;
                    default:
                        // Unknown color index, ignore
                        break;
                }
            }
        }
        if ((ssa[pos] == 'a' && ssa[pos+1] == '&' && ssa[pos+2] == 'H') ||
            (!strcmp(ssa+pos, "alpha") && ssa[pos+5] == '&' && ssa[pos+6] == 'H'))
        {
            // Font alpha markup
            char *endptr;
            uint8_t alpha;
            int alpha_pos = 3;

            if (ssa[1] == 'l')
                alpha_pos = 7;

            alpha = strtol(ssa + pos + alpha_pos, &endptr, 16);
            if (*endptr == '&')
            {
                // SSA alpha is inverted 0 is opaque
                alpha = 255 - alpha;
                switch (index)
                {
                    case -1:
                    case 1:
                        style->fg_alpha = alpha;
                        break;
                    case 2:
                        style->alt_alpha = alpha;
                        break;
                    case 3:
                        style->ol_alpha = alpha;
                        break;
                    case 4:
                        style->bg_alpha = alpha;
                        break;
                    default:
                        // Unknown alpha index, ignore
                        break;
                }
            }
        }
        pos = end;
    }
    if (ssa[pos] == '}')
        pos++;
    return pos;
}

char * hb_ssa_to_text(char *in, int *consumed, hb_subtitle_style_t *style)
{
    int markup_len = 0;
    int in_pos = 0;
    int out_pos = 0;
    char *out = malloc(strlen(in) + 1); // out will never be longer than in

    for (in_pos = 0; in[in_pos] != '\0'; in_pos++)
    {
        if ((markup_len = ssa_update_style(in + in_pos, style)))
        {
            *consumed = in_pos + markup_len;
            out[out_pos++] = '\0';
            return out;
        }
        // Check escape codes
        if (in[in_pos] == '\\')
        {
            in_pos++;
            switch (in[in_pos])
            {
                case '\0':
                    in_pos--;
                    break;
                case 'N':
                case 'n':
                    out[out_pos++] = '\n';
                    break;
                case 'h':
                    out[out_pos++] = ' ';
                    break;
                default:
                    out[out_pos++] = in[in_pos];
                    break;
            }
        }
        else
        {
            out[out_pos++] = in[in_pos];
        }
    }
    *consumed = in_pos;
    out[out_pos++] = '\0';
    return out;
}

void hb_ssa_style_init(hb_subtitle_style_t *style)
{
    style->flags = 0;

    style->fg_rgb    = 0x00FFFFFF;
    style->alt_rgb   = 0x00FFFFFF;
    style->ol_rgb    = 0x000F0F0F;
    style->bg_rgb    = 0x000F0F0F;

    style->fg_alpha  = 0xFF;
    style->alt_alpha = 0xFF;
    style->ol_alpha  = 0xFF;
    style->bg_alpha  = 0xFF;
}

static hb_buffer_t *
ssa_decode_line_to_mkv_ssa( hb_work_object_t * w, hb_buffer_t * in,
                            uint8_t *in_data, int in_size );

/*
 * Decodes a single SSA packet to one or more TEXTSUB or PICTURESUB subtitle packets.
 *
 * SSA packet format:
 * ( Dialogue: Marked,Start,End,Style,Name,MarginL,MarginR,MarginV,Effect,Text CR LF ) +
 *             1      2     3   4     5    6       7       8       9      10
 */
static hb_buffer_t *ssa_decode_packet( hb_work_object_t * w, hb_buffer_t *in )
{
    // Store NULL after the end of the buffer to make using string processing safe
    hb_buffer_realloc(in, ++in->size);
    in->data[in->size - 1] = '\0';

    hb_buffer_list_t list;
    hb_buffer_t *buf;

    hb_buffer_list_clear(&list);
    const char *EOL = "\r\n";
    char *curLine, *curLine_parserData;
    for ( curLine = strtok_r( (char *) in->data, EOL, &curLine_parserData );
          curLine;
          curLine = strtok_r( NULL, EOL, &curLine_parserData ) )
    {
        // Skip empty lines and spaces between adjacent CR and LF
        if (curLine[0] == '\0')
            continue;

        // Decode an individual SSA line
        buf = ssa_decode_line_to_mkv_ssa(w, in,
                                         (uint8_t *)curLine, strlen(curLine));
        hb_buffer_list_append(&list, buf);
    }

    return hb_buffer_list_clear(&list);
}

/*
 * Parses the start and stop time from the specified SSA packet.
 *
 * Returns true if parsing failed; false otherwise.
 */
static int parse_timing_from_ssa_packet( char *in_data, int64_t *in_start, int64_t *in_stop )
{
    /*
     * Parse Start and End fields for timing information
     */
    int start_hr, start_min, start_sec, start_centi;
    int   end_hr,   end_min,   end_sec,   end_centi;
    // SSA subtitles have an empty layer field (bare ',').  The scanf
    // format specifier "%*128[^,]" will not match on a bare ','.  There
    // must be at least one non ',' character in the match.  So the format
    // specifier is placed directly next to the ':' so that the next
    // expected ' ' after the ':' will be the character it matches on
    // when there is no layer field.
    int numPartsRead = sscanf( (char *) in_data, "Dialogue:%*128[^,],"
        "%d:%d:%d.%d,"  // Start
        "%d:%d:%d.%d,", // End
        &start_hr, &start_min, &start_sec, &start_centi,
          &end_hr,   &end_min,   &end_sec,   &end_centi );
    if ( numPartsRead != 8 )
        return 1;

    *in_start = SSA_2_HB_TIME(start_hr, start_min, start_sec, start_centi);
    *in_stop  = SSA_2_HB_TIME(  end_hr,   end_min,   end_sec,   end_centi);

    return 0;
}

static uint8_t *find_field( uint8_t *pos, uint8_t *end, int fieldNum )
{
    int curFieldID = 1;
    while (pos < end)
    {
        if ( *pos++ == ',' )
        {
            curFieldID++;
            if ( curFieldID == fieldNum )
                return pos;
        }
    }
    return NULL;
}

/*
 * SSA line format:
 *   Dialogue: Marked,Start,End,Style,Name,MarginL,MarginR,MarginV,Effect,Text '\0'
 *             1      2     3   4     5    6       7       8       9      10
 *
 * MKV-SSA packet format:
 *   ReadOrder,Marked,          Style,Name,MarginL,MarginR,MarginV,Effect,Text '\0'
 *   1         2                3     4    5       6       7       8      9
 */
static hb_buffer_t *
ssa_decode_line_to_mkv_ssa( hb_work_object_t * w, hb_buffer_t * in,
                            uint8_t *in_data, int in_size )
{
    hb_work_private_t * pv = w->private_data;
    hb_buffer_t * out;

    // Parse values for in->s.start and in->s.stop
    int64_t in_start, in_stop;
    if ( parse_timing_from_ssa_packet( (char *) in_data, &in_start, &in_stop ) )
        goto fail;

    // Convert the SSA packet to MKV-SSA format, which is what libass expects
    char *mkvIn;
    int numPartsRead;
    char *styleToTextFields;
    char *layerField = malloc( in_size );

    // SSA subtitles have an empty layer field (bare ',').  The scanf
    // format specifier "%*128[^,]" will not match on a bare ','.  There
    // must be at least one non ',' character in the match.  So the format
    // specifier is placed directly next to the ':' so that the next
    // expected ' ' after the ':' will be the character it matches on
    // when there is no layer field.
    numPartsRead = sscanf( (char *)in_data, "Dialogue:%128[^,],", layerField );
    if ( numPartsRead != 1 )
        goto fail;

    styleToTextFields = (char *)find_field( in_data, in_data + in_size, 4 );
    if ( styleToTextFields == NULL ) {
        free( layerField );
        goto fail;
    }

    // The sscanf conversion above will result in an extra space
    // before the layerField.  Strip the space.
    char *stripLayerField = layerField;
    for(; *stripLayerField == ' '; stripLayerField++);

    out = hb_buffer_init( in_size + 1 );
    mkvIn = (char*)out->data;

    mkvIn[0] = '\0';
    sprintf(mkvIn, "%d", pv->readOrder++);    // ReadOrder: make this up
    strcat( mkvIn, "," );
    strcat( mkvIn, stripLayerField );
    strcat( mkvIn, "," );
    strcat( mkvIn, (char *)styleToTextFields );

    out->size           = strlen(mkvIn) + 1;
    out->s.frametype    = HB_FRAME_SUBTITLE;
    out->s.start        = in->s.start;
    out->s.duration     = in_stop - in_start;
    out->s.stop         = in->s.start + out->s.duration;
    out->s.scr_sequence = in->s.scr_sequence;

    if( out->size == 0 )
    {
        hb_buffer_close(&out);
    }

    free( layerField );

    return out;

fail:
    hb_log( "decssasub: malformed SSA subtitle packet: %.*s\n", in_size, in_data );
    return NULL;
}

static int decssaInit( hb_work_object_t * w, hb_job_t * job )
{
    hb_work_private_t * pv;

    pv              = calloc( 1, sizeof( hb_work_private_t ) );
    w->private_data = pv;
    pv->job = job;

    return 0;
}

static int decssaWork( hb_work_object_t * w, hb_buffer_t ** buf_in,
                        hb_buffer_t ** buf_out )
{
    hb_buffer_t * in = *buf_in;

#if SSA_VERBOSE_PACKETS
    printf("\nPACKET(%"PRId64",%"PRId64"): %.*s\n", in->s.start/90, in->s.stop/90, in->size, in->data);
#endif

    if (in->s.flags & HB_BUF_FLAG_EOF)
    {
        *buf_out = in;
        *buf_in = NULL;
        return HB_WORK_DONE;
    }

    *buf_out = ssa_decode_packet(w, in);

    return HB_WORK_OK;
}

static void decssaClose( hb_work_object_t * w )
{
    free( w->private_data );
}

hb_work_object_t hb_decssasub =
{
    WORK_DECSSASUB,
    "SSA Subtitle Decoder",
    decssaInit,
    decssaWork,
    decssaClose
};