FFmpeg  4.1.11
tedcaptionsdec.c
Go to the documentation of this file.
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;
34 
35 static const AVOption tedcaptions_options[] = {
36  { "start_time", "set the start time (offset) of the subtitles, in ms",
38  { .i64 = 15000 }, INT64_MIN, INT64_MAX,
40  { NULL },
41 };
42 
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 
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:
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  if (val > INT_MAX/10 - (*cur_byte - '0'))
185  return AVERROR_INVALIDDATA;
186  val = val * 10 + (*cur_byte - '0');
187  next_byte(pb, cur_byte);
188  }
189  *result = val;
190  return 0;
191 }
192 
194 {
195  int ret, cur_byte, start_of_par;
196  AVBPrint label, content;
197  int64_t pos, start, duration;
198  AVPacket *pkt;
199 
200  next_byte(pb, &cur_byte);
201  ret = expect_byte(pb, &cur_byte, '{');
202  if (ret < 0)
203  return AVERROR_INVALIDDATA;
204  ret = parse_label(pb, &cur_byte, &label);
205  if (ret < 0 || strcmp(label.str, "captions"))
206  return AVERROR_INVALIDDATA;
207  ret = expect_byte(pb, &cur_byte, '[');
208  if (ret < 0)
209  return AVERROR_INVALIDDATA;
210  while (1) {
211  content.size = 0;
212  start = duration = AV_NOPTS_VALUE;
213  ret = expect_byte(pb, &cur_byte, '{');
214  if (ret < 0)
215  return ret;
216  pos = avio_tell(pb) - 1;
217  while (1) {
218  ret = parse_label(pb, &cur_byte, &label);
219  if (ret < 0)
220  return ret;
221  if (!strcmp(label.str, "startOfParagraph")) {
222  ret = parse_boolean(pb, &cur_byte, &start_of_par);
223  if (ret < 0)
224  return ret;
225  } else if (!strcmp(label.str, "content")) {
226  ret = parse_string(pb, &cur_byte, &content, 1);
227  if (ret < 0)
228  return ret;
229  } else if (!strcmp(label.str, "startTime")) {
230  ret = parse_int(pb, &cur_byte, &start);
231  if (ret < 0)
232  return ret;
233  } else if (!strcmp(label.str, "duration")) {
234  ret = parse_int(pb, &cur_byte, &duration);
235  if (ret < 0)
236  return ret;
237  } else {
238  return AVERROR_INVALIDDATA;
239  }
240  skip_spaces(pb, &cur_byte);
241  if (cur_byte != ',')
242  break;
243  next_byte(pb, &cur_byte);
244  }
245  ret = expect_byte(pb, &cur_byte, '}');
246  if (ret < 0)
247  return ret;
248 
249  if (!content.size || start == AV_NOPTS_VALUE ||
250  duration == AV_NOPTS_VALUE)
251  return AVERROR_INVALIDDATA;
252  pkt = ff_subtitles_queue_insert(subs, content.str, content.len, 0);
253  if (!pkt)
254  return AVERROR(ENOMEM);
255  pkt->pos = pos;
256  pkt->pts = start;
257  pkt->duration = duration;
258  av_bprint_finalize(&content, NULL);
259 
260  skip_spaces(pb, &cur_byte);
261  if (cur_byte != ',')
262  break;
263  next_byte(pb, &cur_byte);
264  }
265  ret = expect_byte(pb, &cur_byte, ']');
266  if (ret < 0)
267  return ret;
268  ret = expect_byte(pb, &cur_byte, '}');
269  if (ret < 0)
270  return ret;
271  skip_spaces(pb, &cur_byte);
272  if (cur_byte != AVERROR_EOF)
273  return ERR_CODE(cur_byte);
274  return 0;
275 }
276 
278 {
280  AVStream *st = avformat_new_stream(avf, NULL);
281  int ret, i;
282  AVPacket *last;
283 
284  if (!st)
285  return AVERROR(ENOMEM);
286 
287  ret = parse_file(avf->pb, &tc->subs);
288  if (ret < 0) {
289  if (ret == AVERROR_INVALIDDATA)
290  av_log(avf, AV_LOG_ERROR, "Syntax error near offset %"PRId64".\n",
291  avio_tell(avf->pb));
293  return ret;
294  }
296  for (i = 0; i < tc->subs.nb_subs; i++)
297  tc->subs.subs[i].pts += tc->start_time;
298 
299  last = &tc->subs.subs[tc->subs.nb_subs - 1];
302  avpriv_set_pts_info(st, 64, 1, 1000);
303  st->probe_packets = 0;
304  st->start_time = 0;
305  st->duration = last->pts + last->duration;
306  st->cur_dts = 0;
307 
308  return 0;
309 }
310 
312 {
314 
315  return ff_subtitles_queue_read_packet(&tc->subs, packet);
316 }
317 
319 {
321 
323  return 0;
324 }
325 
327 {
328  static const char *const tags[] = {
329  "\"captions\"", "\"duration\"", "\"content\"",
330  "\"startOfParagraph\"", "\"startTime\"",
331  };
332  unsigned i, count = 0;
333  const char *t;
334 
335  if (p->buf[strspn(p->buf, " \t\r\n")] != '{')
336  return 0;
337  for (i = 0; i < FF_ARRAY_ELEMS(tags); i++) {
338  if (!(t = strstr(p->buf, tags[i])))
339  continue;
340  t += strlen(tags[i]);
341  t += strspn(t, " \t\r\n");
342  if (*t == ':')
343  count++;
344  }
345  return count == FF_ARRAY_ELEMS(tags) ? AVPROBE_SCORE_MAX :
346  count ? AVPROBE_SCORE_EXTENSION : 0;
347 }
348 
349 static int tedcaptions_read_seek(AVFormatContext *avf, int stream_index,
350  int64_t min_ts, int64_t ts, int64_t max_ts,
351  int flags)
352 {
354  return ff_subtitles_queue_seek(&tc->subs, avf, stream_index,
355  min_ts, ts, max_ts, flags);
356 }
357 
359  .name = "tedcaptions",
360  .long_name = NULL_IF_CONFIG_SMALL("TED Talks captions"),
361  .priv_data_size = sizeof(TEDCaptionsDemuxer),
362  .priv_class = &tedcaptions_demuxer_class,
367  .read_seek2 = tedcaptions_read_seek,
368 };
#define NULL
Definition: coverity.c:32
const char const char void * val
Definition: avisynth_c.h:771
Bytestream IO Context.
Definition: avio.h:161
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
static int tedcaptions_read_seek(AVFormatContext *avf, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
AVOption.
Definition: opt.h:246
#define AV_OPT_FLAG_SUBTITLE_PARAM
Definition: opt.h:280
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
int64_t pos
byte position in stream, -1 if unknown
Definition: avcodec.h:1465
void avpriv_set_pts_info(AVStream *s, int pts_wrap_bits, unsigned int pts_num, unsigned int pts_den)
Set the time base and wrapping info for a given stream.
Definition: utils.c:4899
int probe_packets
Number of packets to buffer for codec probing.
Definition: avformat.h:1084
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: avcodec.h:3900
const char * b
Definition: vf_curves.c:116
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:191
void ff_subtitles_queue_clean(FFDemuxSubtitlesQueue *q)
Remove and destroy all the subtitles packets.
Definition: subtitles.c:301
#define tc
Definition: regdef.h:69
static AVPacket pkt
static void av_bprint_utf8(AVBPrint *bp, unsigned c)
AVInputFormat ff_tedcaptions_demuxer
int av_bprint_finalize(AVBPrint *buf, char **ret_str)
Finalize a print buffer.
Definition: bprint.c:235
#define BETWEEN(a, amin, amax)
Format I/O context.
Definition: avformat.h:1351
int64_t cur_dts
Definition: avformat.h:1077
const char * class_name
The name of the class; usually it is the same name as the context structure type to which the AVClass...
Definition: log.h:72
static const AVClass tedcaptions_demuxer_class
static int64_t start_time
Definition: ffplay.c:330
uint8_t
#define av_cold
Definition: attributes.h:82
FFDemuxSubtitlesQueue subs
AVOptions.
int ff_subtitles_queue_read_packet(FFDemuxSubtitlesQueue *q, AVPacket *pkt)
Generic read_packet() callback for subtitles demuxers using this queue system.
Definition: subtitles.c:212
int64_t duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: avcodec.h:1463
static int tedcaptions_read_packet(AVFormatContext *avf, AVPacket *packet)
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4469
static void skip_spaces(AVIOContext *pb, int *cur_byte)
int64_t duration
Definition: movenc.c:63
#define AVERROR_EOF
End of file.
Definition: error.h:55
static av_cold int read_close(AVFormatContext *ctx)
Definition: libcdio.c:145
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:557
#define av_log(a,...)
int avio_read(AVIOContext *s, unsigned char *buf, int size)
Read size bytes from AVIOContext into buf.
Definition: aviobuf.c:647
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:258
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
#define AV_BPRINT_SIZE_UNLIMITED
#define AVERROR(e)
Definition: error.h:43
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:188
void av_bprint_init(AVBPrint *buf, unsigned size_init, unsigned size_max)
Definition: bprint.c:69
#define ERR_CODE(c)
enum AVMediaType codec_type
General type of the encoded data.
Definition: avcodec.h:3896
static int parse_label(AVIOContext *pb, int *cur_byte, AVBPrint *bp)
#define fail()
Definition: checkasm.h:117
static int tedcaptions_read_close(AVFormatContext *avf)
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:450
static int read_probe(AVProbeData *pd)
Definition: jvdec.c:55
static int parse_file(AVIOContext *pb, FFDemuxSubtitlesQueue *subs)
static int av_bprint_is_complete(const AVBPrint *buf)
Test if the print buffer is complete (not truncated).
Definition: bprint.h:185
static void next_byte(AVIOContext *pb, int *cur_byte)
static av_cold int tedcaptions_read_header(AVFormatContext *avf)
#define FF_ARRAY_ELEMS(a)
#define av_log2
Definition: intmath.h:83
static int read_header(FFV1Context *f)
Definition: ffv1dec.c:548
Stream structure.
Definition: avformat.h:874
static int read_packet(void *opaque, uint8_t *buf, int buf_size)
Definition: avio_reading.c:42
#define HEX_DIGIT_TEST(c)
int ff_subtitles_queue_seek(FFDemuxSubtitlesQueue *q, AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
Update current_sub_idx to emulate a seek.
Definition: subtitles.c:249
#define AV_BPRINT_SIZE_AUTOMATIC
AVIOContext * pb
I/O context.
Definition: avformat.h:1393
Describe the class of an AVClass context structure.
Definition: log.h:67
#define AV_OPT_FLAG_DECODING_PARAM
a generic parameter which can be set by the user for demuxing or decoding
Definition: opt.h:277
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:458
This structure contains the data a format has to probe a file.
Definition: avformat.h:448
#define flags(name, subs,...)
Definition: cbs_av1.c:610
int64_t duration
Decoding: duration of the stream, in stream time base.
Definition: avformat.h:923
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:460
#define HEX_DIGIT_VAL(c)
Main libavformat public API header.
static int expect_byte(AVIOContext *pb, int *cur_byte, uint8_t c)
raw UTF-8 text
Definition: avcodec.h:653
int64_t start_time
Decoding: pts of the first frame of the stream in presentation order, in stream time base...
Definition: avformat.h:913
static double c[64]
static const AVOption tedcaptions_options[]
AVPacket * subs
array of subtitles packets
Definition: subtitles.h:103
void * priv_data
Format private data.
Definition: avformat.h:1379
static int parse_string(AVIOContext *pb, int *cur_byte, AVBPrint *bp, int full)
void INT64 INT64 count
Definition: avisynth_c.h:690
void INT64 start
Definition: avisynth_c.h:690
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:647
static int parse_boolean(AVIOContext *pb, int *cur_byte, int *result)
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1021
AVPacket * ff_subtitles_queue_insert(FFDemuxSubtitlesQueue *q, const uint8_t *event, size_t len, int merge)
Insert a new subtitle event.
Definition: subtitles.c:111
This structure stores compressed data.
Definition: avcodec.h:1422
int nb_subs
number of subtitles packets
Definition: subtitles.h:104
static av_cold int tedcaptions_read_probe(AVProbeData *p)
void ff_subtitles_queue_finalize(void *log_ctx, FFDemuxSubtitlesQueue *q)
Set missing durations, sort subtitles by PTS (and then byte position), and drop duplicated events...
Definition: subtitles.c:194
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: avcodec.h:1438
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248
void av_bprint_chars(AVBPrint *buf, char c, unsigned n)
Append char c n times to a print buffer.
Definition: bprint.c:140
static int parse_int(AVIOContext *pb, int *cur_byte, int64_t *result)