FFmpeg  4.4.4
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(const 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 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 
75 
76  for (;;) {
77  int i;
78  int64_t pos;
79  AVPacket *sub;
80  const char *p, *identifier, *settings;
81  int identifier_len, settings_len;
82  int64_t ts_start, ts_end;
83 
84  ff_subtitles_read_chunk(s->pb, &cue);
85 
86  if (!cue.len)
87  break;
88 
89  p = identifier = cue.str;
90  pos = avio_tell(s->pb);
91 
92  /* ignore header chunk */
93  if (!strncmp(p, "\xEF\xBB\xBFWEBVTT", 9) ||
94  !strncmp(p, "WEBVTT", 6) ||
95  !strncmp(p, "NOTE", 4))
96  continue;
97 
98  /* optional cue identifier (can be a number like in SRT or some kind of
99  * chaptering id) */
100  for (i = 0; p[i] && p[i] != '\n' && p[i] != '\r'; i++) {
101  if (!strncmp(p + i, "-->", 3)) {
102  identifier = NULL;
103  break;
104  }
105  }
106  if (!identifier)
107  identifier_len = 0;
108  else {
109  identifier_len = strcspn(p, "\r\n");
110  p += identifier_len;
111  if (*p == '\r')
112  p++;
113  if (*p == '\n')
114  p++;
115  }
116 
117  /* cue timestamps */
118  if ((ts_start = read_ts(p)) == AV_NOPTS_VALUE)
119  break;
120  if (!(p = strstr(p, "-->")))
121  break;
122  p += 2;
123  do p++; while (*p == ' ' || *p == '\t');
124  if ((ts_end = read_ts(p)) == AV_NOPTS_VALUE)
125  break;
126 
127  /* optional cue settings */
128  p += strcspn(p, "\n\r\t ");
129  while (*p == '\t' || *p == ' ')
130  p++;
131  settings = p;
132  settings_len = strcspn(p, "\r\n");
133  p += settings_len;
134  if (*p == '\r')
135  p++;
136  if (*p == '\n')
137  p++;
138 
139  /* create packet */
140  sub = ff_subtitles_queue_insert(&webvtt->q, p, strlen(p), 0);
141  if (!sub) {
142  res = AVERROR(ENOMEM);
143  goto end;
144  }
145  sub->pos = pos;
146  sub->pts = ts_start;
147  sub->duration = ts_end - ts_start;
148 
149 #define SET_SIDE_DATA(name, type) do { \
150  if (name##_len) { \
151  uint8_t *buf = av_packet_new_side_data(sub, type, name##_len); \
152  if (!buf) { \
153  res = AVERROR(ENOMEM); \
154  goto end; \
155  } \
156  memcpy(buf, name, name##_len); \
157  } \
158 } while (0)
159 
162  }
163 
164  ff_subtitles_queue_finalize(s, &webvtt->q);
165 
166 end:
167  if (res < 0)
168  ff_subtitles_queue_clean(&webvtt->q);
169  av_bprint_finalize(&cue, 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|AV_OPT_FLAG_DECODING_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, KIND_FLAGS, "webvtt_kind" },
200  { "captions", "WebVTT captions kind", 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_CAPTIONS }, INT_MIN, INT_MAX, KIND_FLAGS, "webvtt_kind" },
201  { "descriptions", "WebVTT descriptions kind", 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_DESCRIPTIONS }, INT_MIN, INT_MAX, KIND_FLAGS, "webvtt_kind" },
202  { "metadata", "WebVTT metadata kind", 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_METADATA }, INT_MIN, INT_MAX, KIND_FLAGS, "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 };
uint8_t
Main libavformat public API header.
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:453
#define AV_DISPOSITION_CAPTIONS
To specify text track kind (different from subtitles default).
Definition: avformat.h:853
#define AV_DISPOSITION_METADATA
Definition: avformat.h:855
#define AV_DISPOSITION_DESCRIPTIONS
Definition: avformat.h:854
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:557
static int read_packet(void *opaque, uint8_t *buf, int buf_size)
Definition: avio_reading.c:42
#define AV_RB24
Definition: intreadwrite.h:64
void av_bprint_init(AVBPrint *buf, unsigned size_init, unsigned size_max)
Definition: bprint.c:69
int av_bprint_finalize(AVBPrint *buf, char **ret_str)
Finalize a print buffer.
Definition: bprint.c:235
#define AV_BPRINT_SIZE_UNLIMITED
#define flags(name, subs,...)
Definition: cbs_av1.c:561
#define ss(width, name, subs,...)
Definition: cbs_vp9.c:261
#define s(width, name)
Definition: cbs_vp9.c:257
#define NULL
Definition: coverity.c:32
static float sub(float src0, float src1)
static int read_header(FFV1Context *f)
Definition: ffv1dec.c:545
@ AV_OPT_TYPE_CONST
Definition: opt.h:234
@ AV_OPT_TYPE_INT
Definition: opt.h:225
@ AV_CODEC_ID_WEBVTT
Definition: codec_id.h:542
@ AV_PKT_DATA_WEBVTT_SETTINGS
The optional settings (rendering instructions) that immediately follow the timestamp specifier of a W...
Definition: packet.h:202
@ AV_PKT_DATA_WEBVTT_IDENTIFIER
The optional first identifier line of a WebVTT cue.
Definition: packet.h:196
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4509
#define AVERROR(e)
Definition: error.h:43
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:235
@ AVMEDIA_TYPE_SUBTITLE
Definition: avutil.h:204
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
int i
Definition: input.c:407
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:4945
static int read_probe(const AVProbeData *pd)
Definition: jvdec.c:55
#define KIND_FLAGS
Definition: webvttdec.c:195
static const AVOption options[]
Definition: webvttdec.c:197
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
#define SET_SIDE_DATA(name, type)
static int webvtt_probe(const AVProbeData *p)
Definition: webvttdec.c:40
static int64_t read_ts(const char *s)
Definition: webvttdec.c:52
static const AVClass webvtt_demuxer_class
Definition: webvttdec.c:206
static int webvtt_read_header(AVFormatContext *s)
Definition: webvttdec.c:60
static int webvtt_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: webvttdec.c:173
static int webvtt_read_close(AVFormatContext *s)
Definition: webvttdec.c:187
#define OFFSET(x)
Definition: webvttdec.c:194
AVInputFormat ff_webvtt_demuxer
Definition: webvttdec.c:213
common internal API header
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:117
static av_cold int read_close(AVFormatContext *ctx)
Definition: libcdio.c:145
AVOptions.
unsigned int pos
Definition: spdifenc.c:412
Describe the class of an AVClass context structure.
Definition: log.h:67
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
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:56
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:60
Format I/O context.
Definition: avformat.h:1232
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:645
AVOption.
Definition: opt.h:248
This structure stores compressed data.
Definition: packet.h:346
This structure contains the data a format has to probe a file.
Definition: avformat.h:441
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:443
Stream structure.
Definition: avformat.h:873
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1038
int disposition
AV_DISPOSITION_* bit field.
Definition: avformat.h:926
FFDemuxSubtitlesQueue q
Definition: webvttdec.c:36
void ff_subtitles_read_chunk(AVIOContext *pb, AVBPrint *buf)
Same as ff_subtitles_read_text_chunk(), but read from an AVIOContext.
Definition: subtitles.c:407
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:255
int ff_subtitles_queue_read_packet(FFDemuxSubtitlesQueue *q, AVPacket *pkt)
Generic read_packet() callback for subtitles demuxers using this queue system.
Definition: subtitles.c:216
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:198
void ff_subtitles_queue_clean(FFDemuxSubtitlesQueue *q)
Remove and destroy all the subtitles packets.
Definition: subtitles.c:307
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
AVPacket * pkt
Definition: movenc.c:59