FFmpeg
tedcaptionsdec.c
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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  ret = expect_byte(pb, cur_byte, '"');
98  if (ret < 0)
99  return ret;
100  while (*cur_byte > 0 && *cur_byte != '"') {
101  if (*cur_byte == '\\') {
102  next_byte(pb, cur_byte);
103  if (*cur_byte < 0)
104  return AVERROR_INVALIDDATA;
105  if ((*cur_byte | 32) == 'u') {
106  unsigned chr = 0, i;
107  for (i = 0; i < 4; i++) {
108  next_byte(pb, cur_byte);
109  if (!HEX_DIGIT_TEST(*cur_byte))
110  return ERR_CODE(*cur_byte);
111  chr = chr * 16 + HEX_DIGIT_VAL(*cur_byte);
112  }
113  av_bprint_utf8(bp, chr);
114  } else {
115  av_bprint_chars(bp, *cur_byte, 1);
116  }
117  } else {
118  av_bprint_chars(bp, *cur_byte, 1);
119  }
120  next_byte(pb, cur_byte);
121  }
122  ret = expect_byte(pb, cur_byte, '"');
123  if (ret < 0)
124  return ret;
125  if (full && !av_bprint_is_complete(bp))
126  return AVERROR(ENOMEM);
127 
128  return 0;
129 }
130 
131 static int parse_label(AVIOContext *pb, int *cur_byte, AVBPrint *bp)
132 {
133  int ret;
134 
136  ret = parse_string(pb, cur_byte, bp, 0);
137  if (ret < 0)
138  return ret;
139  ret = expect_byte(pb, cur_byte, ':');
140  if (ret < 0)
141  return ret;
142  return 0;
143 }
144 
145 static int parse_boolean(AVIOContext *pb, int *cur_byte, int *result)
146 {
147  static const char * const text[] = { "false", "true" };
148  const char *p;
149  int i;
150 
151  skip_spaces(pb, cur_byte);
152  for (i = 0; i < 2; i++) {
153  p = text[i];
154  if (*cur_byte != *p)
155  continue;
156  for (; *p; p++, next_byte(pb, cur_byte))
157  if (*cur_byte != *p)
158  return AVERROR_INVALIDDATA;
159  if (BETWEEN(*cur_byte | 32, 'a', 'z'))
160  return AVERROR_INVALIDDATA;
161  *result = i;
162  return 0;
163  }
164  return AVERROR_INVALIDDATA;
165 }
166 
167 static int parse_int(AVIOContext *pb, int *cur_byte, int64_t *result)
168 {
169  int64_t val = 0;
170 
171  skip_spaces(pb, cur_byte);
172  if ((unsigned)*cur_byte - '0' > 9)
173  return AVERROR_INVALIDDATA;
174  while (BETWEEN(*cur_byte, '0', '9')) {
175  if (val > INT_MAX/10 - (*cur_byte - '0'))
176  return AVERROR_INVALIDDATA;
177  val = val * 10 + (*cur_byte - '0');
178  next_byte(pb, cur_byte);
179  }
180  *result = val;
181  return 0;
182 }
183 
185 {
186  int ret, cur_byte, start_of_par;
187  AVBPrint label, content;
188  int64_t pos, start, duration;
189  AVPacket *pkt;
190 
192 
193  next_byte(pb, &cur_byte);
194  ret = expect_byte(pb, &cur_byte, '{');
195  if (ret < 0)
196  return AVERROR_INVALIDDATA;
197  ret = parse_label(pb, &cur_byte, &label);
198  if (ret < 0 || strcmp(label.str, "captions"))
199  return AVERROR_INVALIDDATA;
200  ret = expect_byte(pb, &cur_byte, '[');
201  if (ret < 0)
202  return AVERROR_INVALIDDATA;
203  while (1) {
204  start = duration = AV_NOPTS_VALUE;
205  ret = expect_byte(pb, &cur_byte, '{');
206  if (ret < 0)
207  goto fail;
208  pos = avio_tell(pb) - 1;
209  while (1) {
210  ret = parse_label(pb, &cur_byte, &label);
211  if (ret < 0)
212  goto fail;
213  if (!strcmp(label.str, "startOfParagraph")) {
214  ret = parse_boolean(pb, &cur_byte, &start_of_par);
215  if (ret < 0)
216  goto fail;
217  } else if (!strcmp(label.str, "content")) {
218  ret = parse_string(pb, &cur_byte, &content, 1);
219  if (ret < 0)
220  goto fail;
221  } else if (!strcmp(label.str, "startTime")) {
222  ret = parse_int(pb, &cur_byte, &start);
223  if (ret < 0)
224  goto fail;
225  } else if (!strcmp(label.str, "duration")) {
226  ret = parse_int(pb, &cur_byte, &duration);
227  if (ret < 0)
228  goto fail;
229  } else {
230  ret = AVERROR_INVALIDDATA;
231  goto fail;
232  }
233  skip_spaces(pb, &cur_byte);
234  if (cur_byte != ',')
235  break;
236  next_byte(pb, &cur_byte);
237  }
238  ret = expect_byte(pb, &cur_byte, '}');
239  if (ret < 0)
240  goto fail;
241 
242  if (!content.size || start == AV_NOPTS_VALUE ||
243  duration == AV_NOPTS_VALUE) {
244  ret = AVERROR_INVALIDDATA;
245  goto fail;
246  }
247  pkt = ff_subtitles_queue_insert(subs, content.str, content.len, 0);
248  if (!pkt) {
249  ret = AVERROR(ENOMEM);
250  goto fail;
251  }
252  pkt->pos = pos;
253  pkt->pts = start;
254  pkt->duration = duration;
255  av_bprint_clear(&content);
256 
257  skip_spaces(pb, &cur_byte);
258  if (cur_byte != ',')
259  break;
260  next_byte(pb, &cur_byte);
261  }
262  ret = expect_byte(pb, &cur_byte, ']');
263  if (ret < 0)
264  goto fail;
265  ret = expect_byte(pb, &cur_byte, '}');
266  if (ret < 0)
267  goto fail;
268  skip_spaces(pb, &cur_byte);
269  if (cur_byte != AVERROR_EOF)
270  ret = ERR_CODE(cur_byte);
271 fail:
272  av_bprint_finalize(&content, NULL);
273  return ret;
274 }
275 
277 {
279  AVStream *st = avformat_new_stream(avf, NULL);
280  int ret, i;
281  AVPacket *last;
282 
283  if (!st)
284  return AVERROR(ENOMEM);
285 
286  ret = parse_file(avf->pb, &tc->subs);
287  if (ret < 0) {
288  if (ret == AVERROR_INVALIDDATA)
289  av_log(avf, AV_LOG_ERROR, "Syntax error near offset %"PRId64".\n",
290  avio_tell(avf->pb));
292  return ret;
293  }
295  for (i = 0; i < tc->subs.nb_subs; i++)
296  tc->subs.subs[i].pts += tc->start_time;
297 
298  last = &tc->subs.subs[tc->subs.nb_subs - 1];
301  avpriv_set_pts_info(st, 64, 1, 1000);
302  st->probe_packets = 0;
303  st->start_time = 0;
304  st->duration = last->pts + last->duration;
305  st->cur_dts = 0;
306 
307  return 0;
308 }
309 
311 {
313 
314  return ff_subtitles_queue_read_packet(&tc->subs, packet);
315 }
316 
318 {
320 
322  return 0;
323 }
324 
326 {
327  static const char *const tags[] = {
328  "\"captions\"", "\"duration\"", "\"content\"",
329  "\"startOfParagraph\"", "\"startTime\"",
330  };
331  unsigned i, count = 0;
332  const char *t;
333 
334  if (p->buf[strspn(p->buf, " \t\r\n")] != '{')
335  return 0;
336  for (i = 0; i < FF_ARRAY_ELEMS(tags); i++) {
337  if (!(t = strstr(p->buf, tags[i])))
338  continue;
339  t += strlen(tags[i]);
340  t += strspn(t, " \t\r\n");
341  if (*t == ':')
342  count++;
343  }
344  return count == FF_ARRAY_ELEMS(tags) ? AVPROBE_SCORE_MAX :
345  count ? AVPROBE_SCORE_EXTENSION : 0;
346 }
347 
348 static int tedcaptions_read_seek(AVFormatContext *avf, int stream_index,
349  int64_t min_ts, int64_t ts, int64_t max_ts,
350  int flags)
351 {
353  return ff_subtitles_queue_seek(&tc->subs, avf, stream_index,
354  min_ts, ts, max_ts, flags);
355 }
356 
358  .name = "tedcaptions",
359  .long_name = NULL_IF_CONFIG_SMALL("TED Talks captions"),
360  .priv_data_size = sizeof(TEDCaptionsDemuxer),
361  .priv_class = &tedcaptions_demuxer_class,
366  .read_seek2 = tedcaptions_read_seek,
367 };
#define NULL
Definition: coverity.c:32
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:248
#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: packet.h:383
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:4905
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: codec_par.h:60
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:235
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:302
#define tc
Definition: regdef.h:69
#define FF_ARRAY_ELEMS(a)
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:1243
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:332
uint8_t
#define av_cold
Definition: attributes.h:88
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: packet.h:381
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
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:4481
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:637
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:194
#define AV_BPRINT_SIZE_UNLIMITED
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:115
void av_bprint_init(AVBPrint *buf, unsigned size_init, unsigned size_max)
Definition: bprint.c:69
unsigned int pos
Definition: spdifenc.c:410
#define ERR_CODE(c)
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:56
static int parse_label(AVIOContext *pb, int *cur_byte, AVBPrint *bp)
GLsizei count
Definition: opengl_enc.c:108
#define fail()
Definition: checkasm.h:133
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:443
#define b
Definition: input.c:41
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)
static int read_header(FFV1Context *f)
Definition: ffv1dec.c:527
Stream structure.
Definition: avformat.h:884
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:250
#define AV_BPRINT_SIZE_AUTOMATIC
AVIOContext * pb
I/O context.
Definition: avformat.h:1285
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:279
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:451
This structure contains the data a format has to probe a file.
Definition: avformat.h:441
#define flags(name, subs,...)
Definition: cbs_av1.c:561
static int read_probe(const AVProbeData *pd)
Definition: jvdec.c:55
void av_bprint_clear(AVBPrint *buf)
Reset the string to "" but keep internal allocated data.
Definition: bprint.c:227
int64_t duration
Decoding: duration of the stream, in stream time base.
Definition: avformat.h:933
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:453
#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: codec_id.h:523
static av_cold int tedcaptions_read_probe(const AVProbeData *p)
int64_t start_time
Decoding: pts of the first frame of the stream in presentation order, in stream time base...
Definition: avformat.h:923
static const AVOption tedcaptions_options[]
AVPacket * subs
array of subtitles packets
Definition: subtitles.h:103
void * priv_data
Format private data.
Definition: avformat.h:1271
static int parse_string(AVIOContext *pb, int *cur_byte, AVBPrint *bp, int full)
and forward the result(frame or status change) to the corresponding input.If nothing is possible
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:654
static int parse_boolean(AVIOContext *pb, int *cur_byte, int *result)
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1049
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
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions
static double val(void *priv, double ch)
Definition: aeval.c:76
This structure stores compressed data.
Definition: packet.h:340
int nb_subs
number of subtitles packets
Definition: subtitles.h:104
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: packet.h:356
int i
Definition: input.c:407
#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)