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webvttdec.c
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1 /*
2  * Copyright (c) 2012 Clément Bœsch
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 /**
22  * @file
23  * WebVTT subtitle demuxer
24  * @see http://dev.w3.org/html5/webvtt/
25  */
26 
27 #include "avformat.h"
28 #include "internal.h"
29 #include "subtitles.h"
30 #include "libavutil/bprint.h"
31 #include "libavutil/intreadwrite.h"
32 #include "libavutil/opt.h"
33 
34 typedef struct {
35  const AVClass *class;
37  int kind;
39 
40 static int webvtt_probe(AVProbeData *p)
41 {
42  const uint8_t *ptr = p->buf;
43 
44  if (AV_RB24(ptr) == 0xEFBBBF)
45  ptr += 3; /* skip UTF-8 BOM */
46  if (!strncmp(ptr, "WEBVTT", 6) &&
47  (!ptr[6] || strchr("\n\r\t ", ptr[6])))
48  return AVPROBE_SCORE_MAX;
49  return 0;
50 }
51 
52 static int64_t read_ts(const char *s)
53 {
54  int hh, mm, ss, ms;
55  if (sscanf(s, "%u:%u:%u.%u", &hh, &mm, &ss, &ms) == 4) return (hh*3600LL + mm*60LL + ss) * 1000LL + ms;
56  if (sscanf(s, "%u:%u.%u", &mm, &ss, &ms) == 3) return ( mm*60LL + ss) * 1000LL + ms;
57  return AV_NOPTS_VALUE;
58 }
59 
61 {
62  WebVTTContext *webvtt = s->priv_data;
63  AVBPrint header, cue;
64  int res = 0;
66 
67  if (!st)
68  return AVERROR(ENOMEM);
69  avpriv_set_pts_info(st, 64, 1, 1000);
72  st->disposition |= webvtt->kind;
73 
76 
77  for (;;) {
78  int i;
79  int64_t pos;
80  AVPacket *sub;
81  const char *p, *identifier, *settings;
82  int identifier_len, settings_len;
83  int64_t ts_start, ts_end;
84 
85  ff_subtitles_read_chunk(s->pb, &cue);
86 
87  if (!cue.len)
88  break;
89 
90  p = identifier = cue.str;
91  pos = avio_tell(s->pb);
92 
93  /* ignore header chunk */
94  if (!strncmp(p, "\xEF\xBB\xBFWEBVTT", 9) ||
95  !strncmp(p, "WEBVTT", 6) ||
96  !strncmp(p, "NOTE", 4))
97  continue;
98 
99  /* optional cue identifier (can be a number like in SRT or some kind of
100  * chaptering id) */
101  for (i = 0; p[i] && p[i] != '\n' && p[i] != '\r'; i++) {
102  if (!strncmp(p + i, "-->", 3)) {
103  identifier = NULL;
104  break;
105  }
106  }
107  if (!identifier)
108  identifier_len = 0;
109  else {
110  identifier_len = strcspn(p, "\r\n");
111  p += identifier_len;
112  if (*p == '\r')
113  p++;
114  if (*p == '\n')
115  p++;
116  }
117 
118  /* cue timestamps */
119  if ((ts_start = read_ts(p)) == AV_NOPTS_VALUE)
120  break;
121  if (!(p = strstr(p, "-->")))
122  break;
123  p += 2;
124  do p++; while (*p == ' ' || *p == '\t');
125  if ((ts_end = read_ts(p)) == AV_NOPTS_VALUE)
126  break;
127 
128  /* optional cue settings */
129  p += strcspn(p, "\n\t ");
130  while (*p == '\t' || *p == ' ')
131  p++;
132  settings = p;
133  settings_len = strcspn(p, "\r\n");
134  p += settings_len;
135  if (*p == '\r')
136  p++;
137  if (*p == '\n')
138  p++;
139 
140  /* create packet */
141  sub = ff_subtitles_queue_insert(&webvtt->q, p, strlen(p), 0);
142  if (!sub) {
143  res = AVERROR(ENOMEM);
144  goto end;
145  }
146  sub->pos = pos;
147  sub->pts = ts_start;
148  sub->duration = ts_end - ts_start;
149 
150 #define SET_SIDE_DATA(name, type) do { \
151  if (name##_len) { \
152  uint8_t *buf = av_packet_new_side_data(sub, type, name##_len); \
153  if (!buf) { \
154  res = AVERROR(ENOMEM); \
155  goto end; \
156  } \
157  memcpy(buf, name, name##_len); \
158  } \
159 } while (0)
160 
163  }
164 
165  ff_subtitles_queue_finalize(s, &webvtt->q);
166 
167 end:
168  av_bprint_finalize(&cue, NULL);
169  av_bprint_finalize(&header, NULL);
170  return res;
171 }
172 
174 {
175  WebVTTContext *webvtt = s->priv_data;
176  return ff_subtitles_queue_read_packet(&webvtt->q, pkt);
177 }
178 
179 static int webvtt_read_seek(AVFormatContext *s, int stream_index,
180  int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
181 {
182  WebVTTContext *webvtt = s->priv_data;
183  return ff_subtitles_queue_seek(&webvtt->q, s, stream_index,
184  min_ts, ts, max_ts, flags);
185 }
186 
188 {
189  WebVTTContext *webvtt = s->priv_data;
190  ff_subtitles_queue_clean(&webvtt->q);
191  return 0;
192 }
193 
194 #define OFFSET(x) offsetof(WebVTTContext, x)
195 #define KIND_FLAGS AV_OPT_FLAG_SUBTITLE_PARAM
196 
197 static const AVOption options[] = {
198  { "kind", "Set kind of WebVTT track", OFFSET(kind), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, KIND_FLAGS, "webvtt_kind" },
199  { "subtitles", "WebVTT subtitles kind", 0, AV_OPT_TYPE_CONST, { .i64 = 0 }, INT_MIN, INT_MAX, 0, "webvtt_kind" },
200  { "captions", "WebVTT captions kind", 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_CAPTIONS }, INT_MIN, INT_MAX, 0, "webvtt_kind" },
201  { "descriptions", "WebVTT descriptions kind", 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_DESCRIPTIONS }, INT_MIN, INT_MAX, 0, "webvtt_kind" },
202  { "metadata", "WebVTT metadata kind", 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_METADATA }, INT_MIN, INT_MAX, 0, "webvtt_kind" },
203  { NULL }
204 };
205 
207  .class_name = "WebVTT demuxer",
208  .item_name = av_default_item_name,
209  .option = options,
210  .version = LIBAVUTIL_VERSION_INT,
211 };
212 
214  .name = "webvtt",
215  .long_name = NULL_IF_CONFIG_SMALL("WebVTT subtitle"),
216  .priv_data_size = sizeof(WebVTTContext),
220  .read_seek2 = webvtt_read_seek,
222  .extensions = "vtt",
223  .priv_class = &webvtt_demuxer_class,
224 };
#define AV_DISPOSITION_METADATA
Definition: avformat.h:862
#define NULL
Definition: coverity.c:32
static int webvtt_read_close(AVFormatContext *s)
Definition: webvttdec.c:187
const char * s
Definition: avisynth_c.h:768
The optional first identifier line of a WebVTT cue.
Definition: avcodec.h:1502
AVOption.
Definition: opt.h:245
#define KIND_FLAGS
Definition: webvttdec.c:195
static int webvtt_read_header(AVFormatContext *s)
Definition: webvttdec.c:60
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
int64_t pos
byte position in stream, -1 if unknown
Definition: avcodec.h:1610
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:4507
void ff_subtitles_read_chunk(AVIOContext *pb, AVBPrint *buf)
Same as ff_subtitles_read_text_chunk(), but read from an AVIOContext.
Definition: subtitles.c:397
static const AVOption options[]
Definition: webvttdec.c:197
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: avcodec.h:3953
void ff_subtitles_queue_clean(FFDemuxSubtitlesQueue *q)
Remove and destroy all the subtitles packets.
Definition: subtitles.c:297
static AVPacket pkt
static int webvtt_read_seek(AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
Definition: webvttdec.c:179
int av_bprint_finalize(AVBPrint *buf, char **ret_str)
Finalize a print buffer.
Definition: bprint.c:235
Format I/O context.
Definition: avformat.h:1327
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
uint8_t
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
static av_cold int end(AVCodecContext *avctx)
Definition: avrndec.c:90
int64_t duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: avcodec.h:1608
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4140
static const AVClass webvtt_demuxer_class
Definition: webvttdec.c:206
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
static const uint8_t header[24]
Definition: sdr2.c:67
#define AV_DISPOSITION_CAPTIONS
To specify text track kind (different from subtitles default).
Definition: avformat.h:860
#define AV_BPRINT_SIZE_UNLIMITED
av_default_item_name
#define AVERROR(e)
Definition: error.h:43
AVInputFormat ff_webvtt_demuxer
Definition: webvttdec.c:213
#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
enum AVMediaType codec_type
General type of the encoded data.
Definition: avcodec.h:3949
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 read_header(FFV1Context *f)
Definition: ffv1dec.c:514
Stream structure.
Definition: avformat.h:878
static int read_packet(void *opaque, uint8_t *buf, int buf_size)
Definition: avio_reading.c:42
#define SET_SIDE_DATA(name, type)
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
#define AV_DISPOSITION_DESCRIPTIONS
Definition: avformat.h:861
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_WB32 unsigned int_TMPL AV_RB24
Definition: bytestream.h:87
AVIOContext * pb
I/O context.
Definition: avformat.h:1369
#define ss
Describe the class of an AVClass context structure.
Definition: log.h:67
#define OFFSET(x)
Definition: webvttdec.c:194
This structure contains the data a format has to probe a file.
Definition: avformat.h:461
static int64_t read_ts(const char *s)
Definition: webvttdec.c:52
static int flags
Definition: cpu.c:47
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:473
Main libavformat public API header.
int disposition
AV_DISPOSITION_* bit field.
Definition: avformat.h:936
FFDemuxSubtitlesQueue q
Definition: webvttdec.c:36
The optional settings (rendering instructions) that immediately follow the timestamp specifier of a W...
Definition: avcodec.h:1508
void * priv_data
Format private data.
Definition: avformat.h:1355
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:662
AVCodecParameters * codecpar
Definition: avformat.h:1230
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
static int webvtt_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: webvttdec.c:173
This structure stores compressed data.
Definition: avcodec.h:1567
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:1583
static int webvtt_probe(AVProbeData *p)
Definition: webvttdec.c:40
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:242