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path: root/libavcodec/microdvddec.c (plain)
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1/*
2 * Copyright (c) 2012 Clément Bœsch
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21/**
22 * @file
23 * MicroDVD subtitle decoder
24 *
25 * Based on the specifications found here:
26 * https://trac.videolan.org/vlc/ticket/1825#comment:6
27 */
28
29#include "libavutil/avstring.h"
30#include "libavutil/parseutils.h"
31#include "libavutil/bprint.h"
32#include "avcodec.h"
33#include "ass.h"
34
35static int indexof(const char *s, int c)
36{
37 char *f = strchr(s, c);
38 return f ? (f - s) : -1;
39}
40
41struct microdvd_tag {
42 char key;
43 int persistent;
44 uint32_t data1;
45 uint32_t data2;
46 char *data_string;
47 int data_string_len;
48};
49
50#define MICRODVD_PERSISTENT_OFF 0
51#define MICRODVD_PERSISTENT_ON 1
52#define MICRODVD_PERSISTENT_OPENED 2
53
54// Color, Font, Size, cHarset, stYle, Position, cOordinate
55#define MICRODVD_TAGS "cfshyYpo"
56
57static void microdvd_set_tag(struct microdvd_tag *tags, struct microdvd_tag tag)
58{
59 int tag_index = indexof(MICRODVD_TAGS, tag.key);
60
61 if (tag_index < 0)
62 return;
63 memcpy(&tags[tag_index], &tag, sizeof(tag));
64}
65
66// italic, bold, underline, strike-through
67#define MICRODVD_STYLES "ibus"
68
69/* some samples have lines that start with a / indicating non persistent italic
70 * marker */
71static char *check_for_italic_slash_marker(struct microdvd_tag *tags, char *s)
72{
73 if (*s == '/') {
74 struct microdvd_tag tag = tags[indexof(MICRODVD_TAGS, 'y')];
75 tag.key = 'y';
76 tag.data1 |= 1 << 0 /* 'i' position in MICRODVD_STYLES */;
77 microdvd_set_tag(tags, tag);
78 s++;
79 }
80 return s;
81}
82
83static char *microdvd_load_tags(struct microdvd_tag *tags, char *s)
84{
85 s = check_for_italic_slash_marker(tags, s);
86
87 while (*s == '{') {
88 char *start = s;
89 char tag_char = *(s + 1);
90 struct microdvd_tag tag = {0};
91
92 if (!tag_char || *(s + 2) != ':')
93 break;
94 s += 3;
95
96 switch (tag_char) {
97
98 /* Style */
99 case 'Y':
100 tag.persistent = MICRODVD_PERSISTENT_ON;
101 case 'y':
102 while (*s && *s != '}') {
103 int style_index = indexof(MICRODVD_STYLES, *s);
104
105 if (style_index >= 0)
106 tag.data1 |= (1 << style_index);
107 s++;
108 }
109 if (*s != '}')
110 break;
111 /* We must distinguish persistent and non-persistent styles
112 * to handle this kind of style tags: {y:ib}{Y:us} */
113 tag.key = tag_char;
114 break;
115
116 /* Color */
117 case 'C':
118 tag.persistent = MICRODVD_PERSISTENT_ON;
119 case 'c':
120 while (*s == '$' || *s == '#')
121 s++;
122 tag.data1 = strtol(s, &s, 16) & 0x00ffffff;
123 if (*s != '}')
124 break;
125 tag.key = 'c';
126 break;
127
128 /* Font name */
129 case 'F':
130 tag.persistent = MICRODVD_PERSISTENT_ON;
131 case 'f': {
132 int len = indexof(s, '}');
133 if (len < 0)
134 break;
135 tag.data_string = s;
136 tag.data_string_len = len;
137 s += len;
138 tag.key = 'f';
139 break;
140 }
141
142 /* Font size */
143 case 'S':
144 tag.persistent = MICRODVD_PERSISTENT_ON;
145 case 's':
146 tag.data1 = strtol(s, &s, 10);
147 if (*s != '}')
148 break;
149 tag.key = 's';
150 break;
151
152 /* Charset */
153 case 'H': {
154 //TODO: not yet handled, just parsed.
155 int len = indexof(s, '}');
156 if (len < 0)
157 break;
158 tag.data_string = s;
159 tag.data_string_len = len;
160 s += len;
161 tag.key = 'h';
162 break;
163 }
164
165 /* Position */
166 case 'P':
167 if (!*s)
168 break;
169 tag.persistent = MICRODVD_PERSISTENT_ON;
170 tag.data1 = (*s++ == '1');
171 if (*s != '}')
172 break;
173 tag.key = 'p';
174 break;
175
176 /* Coordinates */
177 case 'o':
178 tag.persistent = MICRODVD_PERSISTENT_ON;
179 tag.data1 = strtol(s, &s, 10);
180 if (*s != ',')
181 break;
182 s++;
183 tag.data2 = strtol(s, &s, 10);
184 if (*s != '}')
185 break;
186 tag.key = 'o';
187 break;
188
189 default: /* Unknown tag, we consider it's text */
190 break;
191 }
192
193 if (tag.key == 0)
194 return start;
195
196 microdvd_set_tag(tags, tag);
197 s++;
198 }
199 return check_for_italic_slash_marker(tags, s);
200}
201
202static void microdvd_open_tags(AVBPrint *new_line, struct microdvd_tag *tags)
203{
204 int i, sidx;
205 for (i = 0; i < sizeof(MICRODVD_TAGS) - 1; i++) {
206 if (tags[i].persistent == MICRODVD_PERSISTENT_OPENED)
207 continue;
208 switch (tags[i].key) {
209 case 'Y':
210 case 'y':
211 for (sidx = 0; sidx < sizeof(MICRODVD_STYLES) - 1; sidx++)
212 if (tags[i].data1 & (1 << sidx))
213 av_bprintf(new_line, "{\\%c1}", MICRODVD_STYLES[sidx]);
214 break;
215
216 case 'c':
217 av_bprintf(new_line, "{\\c&H%06"PRIX32"&}", tags[i].data1);
218 break;
219
220 case 'f':
221 av_bprintf(new_line, "{\\fn%.*s}",
222 tags[i].data_string_len, tags[i].data_string);
223 break;
224
225 case 's':
226 av_bprintf(new_line, "{\\fs%"PRId32"}", tags[i].data1);
227 break;
228
229 case 'p':
230 if (tags[i].data1 == 0)
231 av_bprintf(new_line, "{\\an8}");
232 break;
233
234 case 'o':
235 av_bprintf(new_line, "{\\pos(%"PRId32",%"PRId32")}",
236 tags[i].data1, tags[i].data2);
237 break;
238 }
239 if (tags[i].persistent == MICRODVD_PERSISTENT_ON)
240 tags[i].persistent = MICRODVD_PERSISTENT_OPENED;
241 }
242}
243
244static void microdvd_close_no_persistent_tags(AVBPrint *new_line,
245 struct microdvd_tag *tags)
246{
247 int i, sidx;
248
249 for (i = sizeof(MICRODVD_TAGS) - 2; i >= 0; i--) {
250 if (tags[i].persistent != MICRODVD_PERSISTENT_OFF)
251 continue;
252 switch (tags[i].key) {
253
254 case 'y':
255 for (sidx = sizeof(MICRODVD_STYLES) - 2; sidx >= 0; sidx--)
256 if (tags[i].data1 & (1 << sidx))
257 av_bprintf(new_line, "{\\%c0}", MICRODVD_STYLES[sidx]);
258 break;
259
260 case 'c':
261 av_bprintf(new_line, "{\\c}");
262 break;
263
264 case 'f':
265 av_bprintf(new_line, "{\\fn}");
266 break;
267
268 case 's':
269 av_bprintf(new_line, "{\\fs}");
270 break;
271 }
272 tags[i].key = 0;
273 }
274}
275
276static int microdvd_decode_frame(AVCodecContext *avctx,
277 void *data, int *got_sub_ptr, AVPacket *avpkt)
278{
279 AVSubtitle *sub = data;
280 AVBPrint new_line;
281 char *line = avpkt->data;
282 char *end = avpkt->data + avpkt->size;
283 FFASSDecoderContext *s = avctx->priv_data;
284 struct microdvd_tag tags[sizeof(MICRODVD_TAGS) - 1] = {{0}};
285
286 if (avpkt->size <= 0)
287 return avpkt->size;
288
289 av_bprint_init(&new_line, 0, 2048);
290
291 // subtitle content
292 while (line < end && *line) {
293
294 // parse MicroDVD tags, and open them in ASS
295 line = microdvd_load_tags(tags, line);
296 microdvd_open_tags(&new_line, tags);
297
298 // simple copy until EOL or forced carriage return
299 while (line < end && *line && *line != '|') {
300 av_bprint_chars(&new_line, *line, 1);
301 line++;
302 }
303
304 // line split
305 if (line < end && *line == '|') {
306 microdvd_close_no_persistent_tags(&new_line, tags);
307 av_bprintf(&new_line, "\\N");
308 line++;
309 }
310 }
311 if (new_line.len) {
312 int ret = ff_ass_add_rect(sub, new_line.str, s->readorder++, 0, NULL, NULL);
313 av_bprint_finalize(&new_line, NULL);
314 if (ret < 0)
315 return ret;
316 }
317
318 *got_sub_ptr = sub->num_rects > 0;
319 return avpkt->size;
320}
321
322static int microdvd_init(AVCodecContext *avctx)
323{
324 int i, sidx;
325 AVBPrint font_buf;
326 int font_size = ASS_DEFAULT_FONT_SIZE;
327 int color = ASS_DEFAULT_COLOR;
328 int bold = ASS_DEFAULT_BOLD;
329 int italic = ASS_DEFAULT_ITALIC;
330 int underline = ASS_DEFAULT_UNDERLINE;
331 int alignment = ASS_DEFAULT_ALIGNMENT;
332 struct microdvd_tag tags[sizeof(MICRODVD_TAGS) - 1] = {{0}};
333
334 av_bprint_init(&font_buf, 0, AV_BPRINT_SIZE_AUTOMATIC);
335 av_bprintf(&font_buf, "%s", ASS_DEFAULT_FONT);
336
337 if (avctx->extradata) {
338 microdvd_load_tags(tags, avctx->extradata);
339 for (i = 0; i < sizeof(MICRODVD_TAGS) - 1; i++) {
340 switch (av_tolower(tags[i].key)) {
341 case 'y':
342 for (sidx = 0; sidx < sizeof(MICRODVD_STYLES) - 1; sidx++) {
343 if (tags[i].data1 & (1 << sidx)) {
344 switch (MICRODVD_STYLES[sidx]) {
345 case 'i': italic = 1; break;
346 case 'b': bold = 1; break;
347 case 'u': underline = 1; break;
348 }
349 }
350 }
351 break;
352
353 case 'c': color = tags[i].data1; break;
354 case 's': font_size = tags[i].data1; break;
355 case 'p': alignment = 8; break;
356
357 case 'f':
358 av_bprint_clear(&font_buf);
359 av_bprintf(&font_buf, "%.*s",
360 tags[i].data_string_len, tags[i].data_string);
361 break;
362 }
363 }
364 }
365 return ff_ass_subtitle_header(avctx, font_buf.str, font_size, color,
366 ASS_DEFAULT_BACK_COLOR, bold, italic,
367 underline, ASS_DEFAULT_BORDERSTYLE,
368 alignment);
369}
370
371AVCodec ff_microdvd_decoder = {
372 .name = "microdvd",
373 .long_name = NULL_IF_CONFIG_SMALL("MicroDVD subtitle"),
374 .type = AVMEDIA_TYPE_SUBTITLE,
375 .id = AV_CODEC_ID_MICRODVD,
376 .init = microdvd_init,
377 .decode = microdvd_decode_frame,
378 .flush = ff_ass_decoder_flush,
379 .priv_data_size = sizeof(FFASSDecoderContext),
380};
381
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