FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavformat/tedcaptionsdec.c
Date: 2026-09-25 02:02:46
Exec Total Coverage
Lines: 9 203 4.4%
Functions: 1 14 7.1%
Branches: 7 138 5.1%

Line Branch Exec Source
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 "demux.h"
27 #include "internal.h"
28 #include "subtitles.h"
29
30 typedef struct {
31 AVClass *class;
32 int64_t start_time;
33 FFDemuxSubtitlesQueue subs;
34 } TEDCaptionsDemuxer;
35
36 static const AVOption tedcaptions_options[] = {
37 { "start_time", "set the start time (offset) of the subtitles, in ms",
38 offsetof(TEDCaptionsDemuxer, start_time), AV_OPT_TYPE_INT64,
39 { .i64 = 15000 }, INT64_MIN, INT64_MAX,
40 AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM },
41 { NULL },
42 };
43
44 static const AVClass tedcaptions_demuxer_class = {
45 .class_name = "tedcaptions_demuxer",
46 .item_name = av_default_item_name,
47 .option = tedcaptions_options,
48 .version = LIBAVUTIL_VERSION_INT,
49 };
50
51 #define BETWEEN(a, amin, amax) ((unsigned)((a) - (amin)) <= (amax) - (amin))
52
53 #define HEX_DIGIT_TEST(c) (BETWEEN(c, '0', '9') || BETWEEN((c) | 32, 'a', 'z'))
54 #define HEX_DIGIT_VAL(c) ((c) <= '9' ? (c) - '0' : ((c) | 32) - 'a' + 10)
55 #define ERR_CODE(c) ((c) < 0 ? (c) : AVERROR_INVALIDDATA)
56
57 ✗ static void av_bprint_utf8(AVBPrint *bp, unsigned c)
58 {
59 int bytes, i;
60
61 ✗ if (c <= 0x7F) {
62 ✗ av_bprint_chars(bp, c, 1);
63 ✗ return;
64 }
65 ✗ bytes = (av_log2(c) - 2) / 5;
66 ✗ av_bprint_chars(bp, (c >> (bytes * 6)) | ((0xFF80 >> bytes) & 0xFF), 1);
67 ✗ for (i = bytes - 1; i >= 0; i--)
68 ✗ av_bprint_chars(bp, ((c >> (i * 6)) & 0x3F) | 0x80, 1);
69 }
70
71 ✗ static void next_byte(AVIOContext *pb, int *cur_byte)
72 {
73 uint8_t b;
74 ✗ int ret = avio_read(pb, &b, 1);
75 ✗ *cur_byte = ret > 0 ? b : ret == 0 ? AVERROR_EOF : ret;
76 ✗ }
77
78 ✗ static void skip_spaces(AVIOContext *pb, int *cur_byte)
79 {
80 ✗ while (*cur_byte == ' ' || *cur_byte == '\t' ||
81 ✗ *cur_byte == '\n' || *cur_byte == '\r')
82 ✗ next_byte(pb, cur_byte);
83 ✗ }
84
85 ✗ static int expect_byte(AVIOContext *pb, int *cur_byte, uint8_t c)
86 {
87 ✗ skip_spaces(pb, cur_byte);
88 ✗ if (*cur_byte != c)
89 ✗ return ERR_CODE(*cur_byte);
90 ✗ next_byte(pb, cur_byte);
91 ✗ return 0;
92 }
93
94 ✗ static int parse_string(AVIOContext *pb, int *cur_byte, AVBPrint *bp, int full)
95 {
96 int ret;
97
98 ✗ ret = expect_byte(pb, cur_byte, '"');
99 ✗ if (ret < 0)
100 ✗ return ret;
101 ✗ while (*cur_byte > 0 && *cur_byte != '"') {
102 ✗ if (*cur_byte == '\\') {
103 ✗ next_byte(pb, cur_byte);
104 ✗ if (*cur_byte < 0)
105 ✗ return AVERROR_INVALIDDATA;
106 ✗ if ((*cur_byte | 32) == 'u') {
107 ✗ unsigned chr = 0, i;
108 ✗ for (i = 0; i < 4; i++) {
109 ✗ next_byte(pb, cur_byte);
110 ✗ if (!HEX_DIGIT_TEST(*cur_byte))
111 ✗ return ERR_CODE(*cur_byte);
112 ✗ chr = chr * 16 + HEX_DIGIT_VAL(*cur_byte);
113 }
114 ✗ av_bprint_utf8(bp, chr);
115 } else {
116 ✗ av_bprint_chars(bp, *cur_byte, 1);
117 }
118 } else {
119 ✗ av_bprint_chars(bp, *cur_byte, 1);
120 }
121 ✗ next_byte(pb, cur_byte);
122 }
123 ✗ ret = expect_byte(pb, cur_byte, '"');
124 ✗ if (ret < 0)
125 ✗ return ret;
126 ✗ if (full && !av_bprint_is_complete(bp))
127 ✗ return AVERROR(ENOMEM);
128
129 ✗ return 0;
130 }
131
132 ✗ static int parse_label(AVIOContext *pb, int *cur_byte, AVBPrint *bp)
133 {
134 int ret;
135
136 ✗ av_bprint_init(bp, 0, AV_BPRINT_SIZE_AUTOMATIC);
137 ✗ ret = parse_string(pb, cur_byte, bp, 0);
138 ✗ if (ret < 0)
139 ✗ return ret;
140 ✗ ret = expect_byte(pb, cur_byte, ':');
141 ✗ if (ret < 0)
142 ✗ return ret;
143 ✗ return 0;
144 }
145
146 ✗ static int parse_boolean(AVIOContext *pb, int *cur_byte, int *result)
147 {
148 static const char * const text[] = { "false", "true" };
149 const char *p;
150 int i;
151
152 ✗ skip_spaces(pb, cur_byte);
153 ✗ for (i = 0; i < 2; i++) {
154 ✗ p = text[i];
155 ✗ if (*cur_byte != *p)
156 ✗ continue;
157 ✗ for (; *p; p++, next_byte(pb, cur_byte))
158 ✗ if (*cur_byte != *p)
159 ✗ return AVERROR_INVALIDDATA;
160 ✗ if (BETWEEN(*cur_byte | 32, 'a', 'z'))
161 ✗ return AVERROR_INVALIDDATA;
162 ✗ *result = i;
163 ✗ return 0;
164 }
165 ✗ return AVERROR_INVALIDDATA;
166 }
167
168 ✗ static int parse_int(AVIOContext *pb, int *cur_byte, int64_t *result)
169 {
170 ✗ int64_t val = 0;
171
172 ✗ skip_spaces(pb, cur_byte);
173 ✗ if ((unsigned)*cur_byte - '0' > 9)
174 ✗ return AVERROR_INVALIDDATA;
175 ✗ while (BETWEEN(*cur_byte, '0', '9')) {
176 ✗ if (val > INT_MAX/10 - (*cur_byte - '0'))
177 ✗ return AVERROR_INVALIDDATA;
178 ✗ val = val * 10 + (*cur_byte - '0');
179 ✗ next_byte(pb, cur_byte);
180 }
181 ✗ *result = val;
182 ✗ return 0;
183 }
184
185 ✗ static int parse_file(AVIOContext *pb, FFDemuxSubtitlesQueue *subs)
186 {
187 int ret, cur_byte, start_of_par;
188 AVBPrint label, content;
189 int64_t pos, start, duration;
190 AVPacket *pkt;
191
192 ✗ av_bprint_init(&content, 0, AV_BPRINT_SIZE_UNLIMITED);
193
194 ✗ next_byte(pb, &cur_byte);
195 ✗ ret = expect_byte(pb, &cur_byte, '{');
196 ✗ if (ret < 0)
197 ✗ return AVERROR_INVALIDDATA;
198 ✗ ret = parse_label(pb, &cur_byte, &label);
199 ✗ if (ret < 0 || strcmp(label.str, "captions"))
200 ✗ return AVERROR_INVALIDDATA;
201 ✗ ret = expect_byte(pb, &cur_byte, '[');
202 ✗ if (ret < 0)
203 ✗ return AVERROR_INVALIDDATA;
204 while (1) {
205 ✗ start = duration = AV_NOPTS_VALUE;
206 ✗ ret = expect_byte(pb, &cur_byte, '{');
207 ✗ if (ret < 0)
208 ✗ goto fail;
209 ✗ pos = avio_tell(pb) - 1;
210 while (1) {
211 ✗ ret = parse_label(pb, &cur_byte, &label);
212 ✗ if (ret < 0)
213 ✗ goto fail;
214 ✗ if (!strcmp(label.str, "startOfParagraph")) {
215 ✗ ret = parse_boolean(pb, &cur_byte, &start_of_par);
216 ✗ if (ret < 0)
217 ✗ goto fail;
218 ✗ } else if (!strcmp(label.str, "content")) {
219 ✗ ret = parse_string(pb, &cur_byte, &content, 1);
220 ✗ if (ret < 0)
221 ✗ goto fail;
222 ✗ } else if (!strcmp(label.str, "startTime")) {
223 ✗ ret = parse_int(pb, &cur_byte, &start);
224 ✗ if (ret < 0)
225 ✗ goto fail;
226 ✗ } else if (!strcmp(label.str, "duration")) {
227 ✗ ret = parse_int(pb, &cur_byte, &duration);
228 ✗ if (ret < 0)
229 ✗ goto fail;
230 } else {
231 ✗ ret = AVERROR_INVALIDDATA;
232 ✗ goto fail;
233 }
234 ✗ skip_spaces(pb, &cur_byte);
235 ✗ if (cur_byte != ',')
236 ✗ break;
237 ✗ next_byte(pb, &cur_byte);
238 }
239 ✗ ret = expect_byte(pb, &cur_byte, '}');
240 ✗ if (ret < 0)
241 ✗ goto fail;
242
243 ✗ if (!content.size || start == AV_NOPTS_VALUE ||
244 ✗ duration == AV_NOPTS_VALUE) {
245 ✗ ret = AVERROR_INVALIDDATA;
246 ✗ goto fail;
247 }
248 ✗ pkt = ff_subtitles_queue_insert_bprint(subs, &content, 0);
249 ✗ if (!pkt) {
250 ✗ ret = AVERROR(ENOMEM);
251 ✗ goto fail;
252 }
253 ✗ pkt->pos = pos;
254 ✗ pkt->pts = start;
255 ✗ pkt->duration = duration;
256 ✗ av_bprint_clear(&content);
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 ✗ goto fail;
266 ✗ ret = expect_byte(pb, &cur_byte, '}');
267 ✗ if (ret < 0)
268 ✗ goto fail;
269 ✗ skip_spaces(pb, &cur_byte);
270 ✗ if (cur_byte != AVERROR_EOF)
271 ✗ ret = ERR_CODE(cur_byte);
272 ✗ fail:
273 ✗ av_bprint_finalize(&content, NULL);
274 ✗ return ret;
275 }
276
277 ✗ static av_cold int tedcaptions_read_header(AVFormatContext *avf)
278 {
279 ✗ TEDCaptionsDemuxer *tc = avf->priv_data;
280 ✗ AVStream *st = avformat_new_stream(avf, NULL);
281 FFStream *sti;
282 int ret, i;
283 AVPacket *last;
284
285 ✗ if (!st)
286 ✗ return AVERROR(ENOMEM);
287
288 ✗ sti = ffstream(st);
289 ✗ ret = parse_file(avf->pb, &tc->subs);
290 ✗ if (ret < 0) {
291 ✗ if (ret == AVERROR_INVALIDDATA)
292 ✗ av_log(avf, AV_LOG_ERROR, "Syntax error near offset %"PRId64".\n",
293 avio_tell(avf->pb));
294 ✗ return ret;
295 }
296 ✗ ff_subtitles_queue_finalize(avf, &tc->subs);
297 ✗ for (i = 0; i < tc->subs.nb_subs; i++)
298 ✗ tc->subs.subs[i]->pts += tc->start_time;
299
300 ✗ last = tc->subs.subs[tc->subs.nb_subs - 1];
301 ✗ st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
302 ✗ st->codecpar->codec_id = AV_CODEC_ID_TEXT;
303 ✗ avpriv_set_pts_info(st, 64, 1, 1000);
304 ✗ sti->probe_packets = 0;
305 ✗ st->start_time = 0;
306 ✗ st->duration = last->pts + last->duration;
307 ✗ sti->cur_dts = 0;
308
309 ✗ return 0;
310 }
311
312 ✗ static int tedcaptions_read_packet(AVFormatContext *avf, AVPacket *packet)
313 {
314 ✗ TEDCaptionsDemuxer *tc = avf->priv_data;
315
316 ✗ return ff_subtitles_queue_read_packet(&tc->subs, packet);
317 }
318
319 ✗ static int tedcaptions_read_close(AVFormatContext *avf)
320 {
321 ✗ TEDCaptionsDemuxer *tc = avf->priv_data;
322
323 ✗ ff_subtitles_queue_clean(&tc->subs);
324 ✗ return 0;
325 }
326
327 8064 static av_cold int tedcaptions_read_probe(const AVProbeData *p)
328 {
329 static const char *const tags[] = {
330 "\"captions\"", "\"duration\"", "\"content\"",
331 "\"startOfParagraph\"", "\"startTime\"",
332 };
333 8064 unsigned i, count = 0;
334 const char *t;
335
336
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8064 if (p->buf[strspn(p->buf, " \t\r\n")] != '{')
337 8061 return 0;
338
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18 for (i = 0; i < FF_ARRAY_ELEMS(tags); i++) {
339
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15 if (!(t = strstr(p->buf, tags[i])))
340 15 continue;
341 ✗ t += strlen(tags[i]);
342 ✗ t += strspn(t, " \t\r\n");
343 ✗ if (*t == ':')
344 ✗ count++;
345 }
346
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6 return count == FF_ARRAY_ELEMS(tags) ? AVPROBE_SCORE_MAX :
347
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3 count ? AVPROBE_SCORE_EXTENSION : 0;
348 }
349
350 ✗ static int tedcaptions_read_seek(AVFormatContext *avf, int stream_index,
351 int64_t min_ts, int64_t ts, int64_t max_ts,
352 int flags)
353 {
354 ✗ TEDCaptionsDemuxer *tc = avf->priv_data;
355 ✗ return ff_subtitles_queue_seek(&tc->subs, avf, stream_index,
356 min_ts, ts, max_ts, flags);
357 }
358
359 const FFInputFormat ff_tedcaptions_demuxer = {
360 .p.name = "tedcaptions",
361 .p.long_name = NULL_IF_CONFIG_SMALL("TED Talks captions"),
362 .p.priv_class = &tedcaptions_demuxer_class,
363 .priv_data_size = sizeof(TEDCaptionsDemuxer),
364 .flags_internal = FF_INFMT_FLAG_INIT_CLEANUP,
365 .read_header = tedcaptions_read_header,
366 .read_packet = tedcaptions_read_packet,
367 .read_close = tedcaptions_read_close,
368 .read_probe = tedcaptions_read_probe,
369 .read_seek2 = tedcaptions_read_seek,
370 };
371