FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
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 
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:
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 
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 
276 {
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));
288  return ret;
289  }
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);
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 
310 {
312 
313  return ff_subtitles_queue_read_packet(&tc->subs, packet);
314 }
315 
317 {
319 
321  return 0;
322 }
323 
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 {
352  return ff_subtitles_queue_seek(&tc->subs, avf, stream_index,
353  min_ts, ts, max_ts, flags);
354 }
355 
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,
365  .read_seek2 = tedcaptions_read_seek,
366 };
#define NULL
Definition: coverity.c:32
const char const char void * val
Definition: avisynth_c.h:771
Bytestream IO Context.
Definition: avio.h:147
#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:245
#define AV_OPT_FLAG_SUBTITLE_PARAM
Definition: opt.h:282
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
int64_t pos
byte position in stream, -1 if unknown
Definition: avcodec.h:1620
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:4549
int probe_packets
Number of packets to buffer for codec probing.
Definition: avformat.h:1060
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: avcodec.h:3979
const char * b
Definition: vf_curves.c:113
int av_log2(unsigned v)
Definition: intmath.c:26
void ff_subtitles_queue_clean(FFDemuxSubtitlesQueue *q)
Remove and destroy all the subtitles packets.
Definition: subtitles.c:297
#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:1330
int64_t cur_dts
Definition: avformat.h:1053
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:329
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:208
int64_t duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: avcodec.h:1618
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:4182
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:511
#define av_log(a,...)
int avio_read(AVIOContext *s, unsigned char *buf, int size)
Read size bytes from AVIOContext into buf.
Definition: aviobuf.c:604
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
av_default_item_name
#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:176
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:3975
static int parse_label(AVIOContext *pb, int *cur_byte, AVBPrint *bp)
GLsizei count
Definition: opengl_enc.c:109
#define fail()
Definition: checkasm.h:82
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:463
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)
static int read_header(FFV1Context *f)
Definition: ffv1dec.c:514
Stream structure.
Definition: avformat.h:881
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:245
AVIOContext * pb
I/O context.
Definition: avformat.h:1372
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:276
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:471
This structure contains the data a format has to probe a file.
Definition: avformat.h:461
static int flags
Definition: cpu.c:47
int64_t duration
Decoding: duration of the stream, in stream time base.
Definition: avformat.h:935
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:473
#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:606
int64_t start_time
Decoding: pts of the first frame of the stream in presentation order, in stream time base...
Definition: avformat.h:928
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:1358
static int parse_string(AVIOContext *pb, int *cur_byte, AVBPrint *bp, int full)
void INT64 start
Definition: avisynth_c.h:690
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:662
static int parse_boolean(AVIOContext *pb, int *cur_byte, int *result)
AVCodecParameters * codecpar
Definition: avformat.h:1233
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:1577
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:193
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: avcodec.h:1593
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:242
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)