FFmpeg
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  size_t 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  av_bprint_finalize(&cue, NULL);
168  return res;
169 }
170 
172 {
173  WebVTTContext *webvtt = s->priv_data;
174  return ff_subtitles_queue_read_packet(&webvtt->q, pkt);
175 }
176 
177 static int webvtt_read_seek(AVFormatContext *s, int stream_index,
178  int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
179 {
180  WebVTTContext *webvtt = s->priv_data;
181  return ff_subtitles_queue_seek(&webvtt->q, s, stream_index,
182  min_ts, ts, max_ts, flags);
183 }
184 
186 {
187  WebVTTContext *webvtt = s->priv_data;
188  ff_subtitles_queue_clean(&webvtt->q);
189  return 0;
190 }
191 
192 #define OFFSET(x) offsetof(WebVTTContext, x)
193 #define KIND_FLAGS AV_OPT_FLAG_SUBTITLE_PARAM|AV_OPT_FLAG_DECODING_PARAM
194 
195 static const AVOption options[] = {
196  { "kind", "Set kind of WebVTT track", OFFSET(kind), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, KIND_FLAGS, "webvtt_kind" },
197  { "subtitles", "WebVTT subtitles kind", 0, AV_OPT_TYPE_CONST, { .i64 = 0 }, INT_MIN, INT_MAX, KIND_FLAGS, "webvtt_kind" },
198  { "captions", "WebVTT captions kind", 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_CAPTIONS }, INT_MIN, INT_MAX, KIND_FLAGS, "webvtt_kind" },
199  { "descriptions", "WebVTT descriptions kind", 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_DESCRIPTIONS }, INT_MIN, INT_MAX, KIND_FLAGS, "webvtt_kind" },
200  { "metadata", "WebVTT metadata kind", 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_METADATA }, INT_MIN, INT_MAX, KIND_FLAGS, "webvtt_kind" },
201  { NULL }
202 };
203 
205  .class_name = "WebVTT demuxer",
206  .item_name = av_default_item_name,
207  .option = options,
208  .version = LIBAVUTIL_VERSION_INT,
209 };
210 
212  .name = "webvtt",
213  .long_name = NULL_IF_CONFIG_SMALL("WebVTT subtitle"),
214  .priv_data_size = sizeof(WebVTTContext),
215  .flags_internal = FF_FMT_INIT_CLEANUP,
219  .read_seek2 = webvtt_read_seek,
221  .extensions = "vtt",
222  .priv_class = &webvtt_demuxer_class,
223 };
AVMEDIA_TYPE_SUBTITLE
@ AVMEDIA_TYPE_SUBTITLE
Definition: avutil.h:204
AV_BPRINT_SIZE_UNLIMITED
#define AV_BPRINT_SIZE_UNLIMITED
FF_FMT_INIT_CLEANUP
#define FF_FMT_INIT_CLEANUP
For an AVInputFormat with this flag set read_close() needs to be called by the caller upon read_heade...
Definition: internal.h:50
AVERROR
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
opt.h
avformat_new_stream
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4374
AVCodecParameters::codec_type
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:56
av_bprint_finalize
int av_bprint_finalize(AVBPrint *buf, char **ret_str)
Finalize a print buffer.
Definition: bprint.c:234
av_bprint_init
void av_bprint_init(AVBPrint *buf, unsigned size_init, unsigned size_max)
Definition: bprint.c:68
sub
static float sub(float src0, float src1)
Definition: dnn_backend_native_layer_mathbinary.c:31
WebVTTContext
Definition: webvttenc.c:32
AVOption
AVOption.
Definition: opt.h:247
AVPROBE_SCORE_MAX
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:458
OFFSET
#define OFFSET(x)
Definition: webvttdec.c:192
read_close
static av_cold int read_close(AVFormatContext *ctx)
Definition: libcdio.c:141
avio_tell
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:538
ss
#define ss(width, name, subs,...)
Definition: cbs_vp9.c:261
ff_subtitles_queue_seek
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:254
AV_PKT_DATA_WEBVTT_SETTINGS
@ AV_PKT_DATA_WEBVTT_SETTINGS
The optional settings (rendering instructions) that immediately follow the timestamp specifier of a W...
Definition: packet.h:202
pkt
AVPacket * pkt
Definition: movenc.c:59
AVInputFormat
Definition: avformat.h:626
intreadwrite.h
s
#define s(width, name)
Definition: cbs_vp9.c:257
ff_webvtt_demuxer
const AVInputFormat ff_webvtt_demuxer
Definition: webvttdec.c:211
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:631
AVProbeData::buf
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:448
ff_subtitles_queue_read_packet
int ff_subtitles_queue_read_packet(FFDemuxSubtitlesQueue *q, AVPacket *pkt)
Generic read_packet() callback for subtitles demuxers using this queue system.
Definition: subtitles.c:215
AV_CODEC_ID_WEBVTT
@ AV_CODEC_ID_WEBVTT
Definition: codec_id.h:538
AVFormatContext
Format I/O context.
Definition: avformat.h:1107
internal.h
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:994
LIBAVUTIL_VERSION_INT
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
read_header
static int read_header(FFV1Context *f)
Definition: ffv1dec.c:527
AVClass
Describe the class of an AVClass context structure.
Definition: log.h:66
NULL
#define NULL
Definition: coverity.c:32
read_probe
static int read_probe(const AVProbeData *pd)
Definition: jvdec.c:55
av_default_item_name
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:235
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:446
KIND_FLAGS
#define KIND_FLAGS
Definition: webvttdec.c:193
AV_DISPOSITION_METADATA
#define AV_DISPOSITION_METADATA
Definition: avformat.h:829
ff_subtitles_queue_insert
AVPacket * ff_subtitles_queue_insert(FFDemuxSubtitlesQueue *q, const uint8_t *event, size_t len, int merge)
Insert a new subtitle event.
Definition: subtitles.c:110
webvtt_demuxer_class
static const AVClass webvtt_demuxer_class
Definition: webvttdec.c:204
AV_DISPOSITION_CAPTIONS
#define AV_DISPOSITION_CAPTIONS
To specify text track kind (different from subtitles default).
Definition: avformat.h:827
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:116
avpriv_set_pts_info
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:4799
AV_NOPTS_VALUE
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248
ff_subtitles_queue_finalize
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:197
FFDemuxSubtitlesQueue
Definition: subtitles.h:102
ff_subtitles_queue_clean
void ff_subtitles_queue_clean(FFDemuxSubtitlesQueue *q)
Remove and destroy all the subtitles packets.
Definition: subtitles.c:306
read_ts
static int64_t read_ts(const char *s)
Definition: webvttdec.c:52
bprint.h
i
int i
Definition: input.c:406
SET_SIDE_DATA
#define SET_SIDE_DATA(name, type)
WebVTTContext::q
FFDemuxSubtitlesQueue q
Definition: webvttdec.c:36
AVStream::disposition
int disposition
AV_DISPOSITION_* bit field.
Definition: avformat.h:894
read_packet
static int read_packet(void *opaque, uint8_t *buf, int buf_size)
Definition: avio_reading.c:42
AVStream
Stream structure.
Definition: avformat.h:847
AVClass::class_name
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:71
ff_subtitles_read_chunk
void ff_subtitles_read_chunk(AVIOContext *pb, AVBPrint *buf)
Same as ff_subtitles_read_text_chunk(), but read from an AVIOContext.
Definition: subtitles.c:427
pos
unsigned int pos
Definition: spdifenc.c:412
avformat.h
AV_DISPOSITION_DESCRIPTIONS
#define AV_DISPOSITION_DESCRIPTIONS
Definition: avformat.h:828
webvtt_read_packet
static int webvtt_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: webvttdec.c:171
options
static const AVOption options[]
Definition: webvttdec.c:195
webvtt_read_close
static int webvtt_read_close(AVFormatContext *s)
Definition: webvttdec.c:185
webvtt_probe
static int webvtt_probe(const AVProbeData *p)
Definition: webvttdec.c:40
subtitles.h
AV_OPT_TYPE_INT
@ AV_OPT_TYPE_INT
Definition: opt.h:224
WebVTTContext::kind
int kind
Definition: webvttdec.c:37
webvtt_read_seek
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:177
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:60
AVPacket
This structure stores compressed data.
Definition: packet.h:350
flags
#define flags(name, subs,...)
Definition: cbs_av1.c:561
AV_PKT_DATA_WEBVTT_IDENTIFIER
@ AV_PKT_DATA_WEBVTT_IDENTIFIER
The optional first identifier line of a WebVTT cue.
Definition: packet.h:196
AV_RB24
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:97
AV_OPT_TYPE_CONST
@ AV_OPT_TYPE_CONST
Definition: opt.h:233
webvtt_read_header
static int webvtt_read_header(AVFormatContext *s)
Definition: webvttdec.c:60