blob: 774d4993b5f1e7c11891ebf69cfb699d48562425
1 | /* |
2 | * TED Talks captions format decoder |
3 | * Copyright (c) 2012 Nicolas George |
4 | * |
5 | * This file is part of FFmpeg. |
6 | * |
7 | * FFmpeg is free software; you can redistribute it and/or |
8 | * modify it under the terms of the GNU Lesser General Public |
9 | * License as published by the Free Software Foundation; either |
10 | * version 2.1 of the License, or (at your option) any later version. |
11 | * |
12 | * FFmpeg is distributed in the hope that it will be useful, |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
15 | * Lesser General Public License for more details. |
16 | * |
17 | * You should have received a copy of the GNU Lesser General Public |
18 | * License along with FFmpeg; if not, write to the Free Software |
19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
20 | */ |
21 | |
22 | #include "libavutil/bprint.h" |
23 | #include "libavutil/log.h" |
24 | #include "libavutil/opt.h" |
25 | #include "avformat.h" |
26 | #include "internal.h" |
27 | #include "subtitles.h" |
28 | |
29 | typedef struct { |
30 | AVClass *class; |
31 | int64_t start_time; |
32 | FFDemuxSubtitlesQueue subs; |
33 | } TEDCaptionsDemuxer; |
34 | |
35 | static const AVOption tedcaptions_options[] = { |
36 | { "start_time", "set the start time (offset) of the subtitles, in ms", |
37 | offsetof(TEDCaptionsDemuxer, start_time), AV_OPT_TYPE_INT64, |
38 | { .i64 = 15000 }, INT64_MIN, INT64_MAX, |
39 | AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM }, |
40 | { NULL }, |
41 | }; |
42 | |
43 | static const AVClass tedcaptions_demuxer_class = { |
44 | .class_name = "tedcaptions_demuxer", |
45 | .item_name = av_default_item_name, |
46 | .option = tedcaptions_options, |
47 | .version = LIBAVUTIL_VERSION_INT, |
48 | }; |
49 | |
50 | #define BETWEEN(a, amin, amax) ((unsigned)((a) - (amin)) <= (amax) - (amin)) |
51 | |
52 | #define HEX_DIGIT_TEST(c) (BETWEEN(c, '0', '9') || BETWEEN((c) | 32, 'a', 'z')) |
53 | #define HEX_DIGIT_VAL(c) ((c) <= '9' ? (c) - '0' : ((c) | 32) - 'a' + 10) |
54 | #define ERR_CODE(c) ((c) < 0 ? (c) : AVERROR_INVALIDDATA) |
55 | |
56 | static void av_bprint_utf8(AVBPrint *bp, unsigned c) |
57 | { |
58 | int bytes, i; |
59 | |
60 | if (c <= 0x7F) { |
61 | av_bprint_chars(bp, c, 1); |
62 | return; |
63 | } |
64 | bytes = (av_log2(c) - 2) / 5; |
65 | av_bprint_chars(bp, (c >> (bytes * 6)) | ((0xFF80 >> bytes) & 0xFF), 1); |
66 | for (i = bytes - 1; i >= 0; i--) |
67 | av_bprint_chars(bp, ((c >> (i * 6)) & 0x3F) | 0x80, 1); |
68 | } |
69 | |
70 | static void next_byte(AVIOContext *pb, int *cur_byte) |
71 | { |
72 | uint8_t b; |
73 | int ret = avio_read(pb, &b, 1); |
74 | *cur_byte = ret > 0 ? b : ret == 0 ? AVERROR_EOF : ret; |
75 | } |
76 | |
77 | static void skip_spaces(AVIOContext *pb, int *cur_byte) |
78 | { |
79 | while (*cur_byte == ' ' || *cur_byte == '\t' || |
80 | *cur_byte == '\n' || *cur_byte == '\r') |
81 | next_byte(pb, cur_byte); |
82 | } |
83 | |
84 | static int expect_byte(AVIOContext *pb, int *cur_byte, uint8_t c) |
85 | { |
86 | skip_spaces(pb, cur_byte); |
87 | if (*cur_byte != c) |
88 | return ERR_CODE(*cur_byte); |
89 | next_byte(pb, cur_byte); |
90 | return 0; |
91 | } |
92 | |
93 | static int parse_string(AVIOContext *pb, int *cur_byte, AVBPrint *bp, int full) |
94 | { |
95 | int ret; |
96 | |
97 | av_bprint_init(bp, 0, full ? -1 : 1); |
98 | ret = expect_byte(pb, cur_byte, '"'); |
99 | if (ret < 0) |
100 | goto fail; |
101 | while (*cur_byte > 0 && *cur_byte != '"') { |
102 | if (*cur_byte == '\\') { |
103 | next_byte(pb, cur_byte); |
104 | if (*cur_byte < 0) { |
105 | ret = AVERROR_INVALIDDATA; |
106 | goto fail; |
107 | } |
108 | if ((*cur_byte | 32) == 'u') { |
109 | unsigned chr = 0, i; |
110 | for (i = 0; i < 4; i++) { |
111 | next_byte(pb, cur_byte); |
112 | if (!HEX_DIGIT_TEST(*cur_byte)) { |
113 | ret = ERR_CODE(*cur_byte); |
114 | goto fail; |
115 | } |
116 | chr = chr * 16 + HEX_DIGIT_VAL(*cur_byte); |
117 | } |
118 | av_bprint_utf8(bp, chr); |
119 | } else { |
120 | av_bprint_chars(bp, *cur_byte, 1); |
121 | } |
122 | } else { |
123 | av_bprint_chars(bp, *cur_byte, 1); |
124 | } |
125 | next_byte(pb, cur_byte); |
126 | } |
127 | ret = expect_byte(pb, cur_byte, '"'); |
128 | if (ret < 0) |
129 | goto fail; |
130 | if (full && !av_bprint_is_complete(bp)) { |
131 | ret = AVERROR(ENOMEM); |
132 | goto fail; |
133 | } |
134 | return 0; |
135 | |
136 | fail: |
137 | av_bprint_finalize(bp, NULL); |
138 | return ret; |
139 | } |
140 | |
141 | static int parse_label(AVIOContext *pb, int *cur_byte, AVBPrint *bp) |
142 | { |
143 | int ret; |
144 | |
145 | ret = parse_string(pb, cur_byte, bp, 0); |
146 | if (ret < 0) |
147 | return ret; |
148 | ret = expect_byte(pb, cur_byte, ':'); |
149 | if (ret < 0) |
150 | return ret; |
151 | return 0; |
152 | } |
153 | |
154 | static int parse_boolean(AVIOContext *pb, int *cur_byte, int *result) |
155 | { |
156 | static const char * const text[] = { "false", "true" }; |
157 | const char *p; |
158 | int i; |
159 | |
160 | skip_spaces(pb, cur_byte); |
161 | for (i = 0; i < 2; i++) { |
162 | p = text[i]; |
163 | if (*cur_byte != *p) |
164 | continue; |
165 | for (; *p; p++, next_byte(pb, cur_byte)) |
166 | if (*cur_byte != *p) |
167 | return AVERROR_INVALIDDATA; |
168 | if (BETWEEN(*cur_byte | 32, 'a', 'z')) |
169 | return AVERROR_INVALIDDATA; |
170 | *result = i; |
171 | return 0; |
172 | } |
173 | return AVERROR_INVALIDDATA; |
174 | } |
175 | |
176 | static int parse_int(AVIOContext *pb, int *cur_byte, int64_t *result) |
177 | { |
178 | int64_t val = 0; |
179 | |
180 | skip_spaces(pb, cur_byte); |
181 | if ((unsigned)*cur_byte - '0' > 9) |
182 | return AVERROR_INVALIDDATA; |
183 | while (BETWEEN(*cur_byte, '0', '9')) { |
184 | val = val * 10 + (*cur_byte - '0'); |
185 | next_byte(pb, cur_byte); |
186 | } |
187 | *result = val; |
188 | return 0; |
189 | } |
190 | |
191 | static int parse_file(AVIOContext *pb, FFDemuxSubtitlesQueue *subs) |
192 | { |
193 | int ret, cur_byte, start_of_par; |
194 | AVBPrint label, content; |
195 | int64_t pos, start, duration; |
196 | AVPacket *pkt; |
197 | |
198 | next_byte(pb, &cur_byte); |
199 | ret = expect_byte(pb, &cur_byte, '{'); |
200 | if (ret < 0) |
201 | return AVERROR_INVALIDDATA; |
202 | ret = parse_label(pb, &cur_byte, &label); |
203 | if (ret < 0 || strcmp(label.str, "captions")) |
204 | return AVERROR_INVALIDDATA; |
205 | ret = expect_byte(pb, &cur_byte, '['); |
206 | if (ret < 0) |
207 | return AVERROR_INVALIDDATA; |
208 | while (1) { |
209 | content.size = 0; |
210 | start = duration = AV_NOPTS_VALUE; |
211 | ret = expect_byte(pb, &cur_byte, '{'); |
212 | if (ret < 0) |
213 | return ret; |
214 | pos = avio_tell(pb) - 1; |
215 | while (1) { |
216 | ret = parse_label(pb, &cur_byte, &label); |
217 | if (ret < 0) |
218 | return ret; |
219 | if (!strcmp(label.str, "startOfParagraph")) { |
220 | ret = parse_boolean(pb, &cur_byte, &start_of_par); |
221 | if (ret < 0) |
222 | return ret; |
223 | } else if (!strcmp(label.str, "content")) { |
224 | ret = parse_string(pb, &cur_byte, &content, 1); |
225 | if (ret < 0) |
226 | return ret; |
227 | } else if (!strcmp(label.str, "startTime")) { |
228 | ret = parse_int(pb, &cur_byte, &start); |
229 | if (ret < 0) |
230 | return ret; |
231 | } else if (!strcmp(label.str, "duration")) { |
232 | ret = parse_int(pb, &cur_byte, &duration); |
233 | if (ret < 0) |
234 | return ret; |
235 | } else { |
236 | return AVERROR_INVALIDDATA; |
237 | } |
238 | skip_spaces(pb, &cur_byte); |
239 | if (cur_byte != ',') |
240 | break; |
241 | next_byte(pb, &cur_byte); |
242 | } |
243 | ret = expect_byte(pb, &cur_byte, '}'); |
244 | if (ret < 0) |
245 | return ret; |
246 | |
247 | if (!content.size || start == AV_NOPTS_VALUE || |
248 | duration == AV_NOPTS_VALUE) |
249 | return AVERROR_INVALIDDATA; |
250 | pkt = ff_subtitles_queue_insert(subs, content.str, content.len, 0); |
251 | if (!pkt) |
252 | return AVERROR(ENOMEM); |
253 | pkt->pos = pos; |
254 | pkt->pts = start; |
255 | pkt->duration = duration; |
256 | av_bprint_finalize(&content, NULL); |
257 | |
258 | skip_spaces(pb, &cur_byte); |
259 | if (cur_byte != ',') |
260 | break; |
261 | next_byte(pb, &cur_byte); |
262 | } |
263 | ret = expect_byte(pb, &cur_byte, ']'); |
264 | if (ret < 0) |
265 | return ret; |
266 | ret = expect_byte(pb, &cur_byte, '}'); |
267 | if (ret < 0) |
268 | return ret; |
269 | skip_spaces(pb, &cur_byte); |
270 | if (cur_byte != AVERROR_EOF) |
271 | return ERR_CODE(cur_byte); |
272 | return 0; |
273 | } |
274 | |
275 | static av_cold int tedcaptions_read_header(AVFormatContext *avf) |
276 | { |
277 | TEDCaptionsDemuxer *tc = avf->priv_data; |
278 | AVStream *st; |
279 | int ret, i; |
280 | AVPacket *last; |
281 | |
282 | ret = parse_file(avf->pb, &tc->subs); |
283 | if (ret < 0) { |
284 | if (ret == AVERROR_INVALIDDATA) |
285 | av_log(avf, AV_LOG_ERROR, "Syntax error near offset %"PRId64".\n", |
286 | avio_tell(avf->pb)); |
287 | ff_subtitles_queue_clean(&tc->subs); |
288 | return ret; |
289 | } |
290 | ff_subtitles_queue_finalize(avf, &tc->subs); |
291 | for (i = 0; i < tc->subs.nb_subs; i++) |
292 | tc->subs.subs[i].pts += tc->start_time; |
293 | |
294 | last = &tc->subs.subs[tc->subs.nb_subs - 1]; |
295 | st = avformat_new_stream(avf, NULL); |
296 | if (!st) |
297 | return AVERROR(ENOMEM); |
298 | st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE; |
299 | st->codecpar->codec_id = AV_CODEC_ID_TEXT; |
300 | avpriv_set_pts_info(st, 64, 1, 1000); |
301 | st->probe_packets = 0; |
302 | st->start_time = 0; |
303 | st->duration = last->pts + last->duration; |
304 | st->cur_dts = 0; |
305 | |
306 | return 0; |
307 | } |
308 | |
309 | static int tedcaptions_read_packet(AVFormatContext *avf, AVPacket *packet) |
310 | { |
311 | TEDCaptionsDemuxer *tc = avf->priv_data; |
312 | |
313 | return ff_subtitles_queue_read_packet(&tc->subs, packet); |
314 | } |
315 | |
316 | static int tedcaptions_read_close(AVFormatContext *avf) |
317 | { |
318 | TEDCaptionsDemuxer *tc = avf->priv_data; |
319 | |
320 | ff_subtitles_queue_clean(&tc->subs); |
321 | return 0; |
322 | } |
323 | |
324 | static av_cold int tedcaptions_read_probe(AVProbeData *p) |
325 | { |
326 | static const char *const tags[] = { |
327 | "\"captions\"", "\"duration\"", "\"content\"", |
328 | "\"startOfParagraph\"", "\"startTime\"", |
329 | }; |
330 | unsigned i, count = 0; |
331 | const char *t; |
332 | |
333 | if (p->buf[strspn(p->buf, " \t\r\n")] != '{') |
334 | return 0; |
335 | for (i = 0; i < FF_ARRAY_ELEMS(tags); i++) { |
336 | if (!(t = strstr(p->buf, tags[i]))) |
337 | continue; |
338 | t += strlen(tags[i]); |
339 | t += strspn(t, " \t\r\n"); |
340 | if (*t == ':') |
341 | count++; |
342 | } |
343 | return count == FF_ARRAY_ELEMS(tags) ? AVPROBE_SCORE_MAX : |
344 | count ? AVPROBE_SCORE_EXTENSION : 0; |
345 | } |
346 | |
347 | static int tedcaptions_read_seek(AVFormatContext *avf, int stream_index, |
348 | int64_t min_ts, int64_t ts, int64_t max_ts, |
349 | int flags) |
350 | { |
351 | TEDCaptionsDemuxer *tc = avf->priv_data; |
352 | return ff_subtitles_queue_seek(&tc->subs, avf, stream_index, |
353 | min_ts, ts, max_ts, flags); |
354 | } |
355 | |
356 | AVInputFormat ff_tedcaptions_demuxer = { |
357 | .name = "tedcaptions", |
358 | .long_name = NULL_IF_CONFIG_SMALL("TED Talks captions"), |
359 | .priv_data_size = sizeof(TEDCaptionsDemuxer), |
360 | .priv_class = &tedcaptions_demuxer_class, |
361 | .read_header = tedcaptions_read_header, |
362 | .read_packet = tedcaptions_read_packet, |
363 | .read_close = tedcaptions_read_close, |
364 | .read_probe = tedcaptions_read_probe, |
365 | .read_seek2 = tedcaptions_read_seek, |
366 | }; |
367 |