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webvttenc.c
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1 /*
2  * Copyright (c) 2013 Matthew Heaney
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 muxer
24  * @see http://dev.w3.org/html5/webvtt/
25  */
26 
27 #include "avformat.h"
28 #include "internal.h"
29 
30 static void webvtt_write_time(AVIOContext *pb, int64_t millisec)
31 {
32  int64_t sec, min, hour;
33  sec = millisec / 1000;
34  millisec -= 1000 * sec;
35  min = sec / 60;
36  sec -= 60 * min;
37  hour = min / 60;
38  min -= 60 * hour;
39 
40  if (hour > 0)
41  avio_printf(pb, "%"PRId64":", hour);
42 
43  avio_printf(pb, "%02"PRId64":%02"PRId64".%03"PRId64"", min, sec, millisec);
44 }
45 
47 {
48  AVStream *s = ctx->streams[0];
49  AVCodecParameters *par = ctx->streams[0]->codecpar;
50  AVIOContext *pb = ctx->pb;
51 
52  if (ctx->nb_streams != 1 || par->codec_id != AV_CODEC_ID_WEBVTT) {
53  av_log(ctx, AV_LOG_ERROR, "Exactly one WebVTT stream is needed.\n");
54  return AVERROR(EINVAL);
55  }
56 
57  avpriv_set_pts_info(s, 64, 1, 1000);
58 
59  avio_printf(pb, "WEBVTT\n");
60  avio_flush(pb);
61 
62  return 0;
63 }
64 
66 {
67  AVIOContext *pb = ctx->pb;
68  int id_size, settings_size;
69  uint8_t *id, *settings;
70 
71  avio_printf(pb, "\n");
72 
74  &id_size);
75 
76  if (id && id_size > 0)
77  avio_printf(pb, "%.*s\n", id_size, id);
78 
79  webvtt_write_time(pb, pkt->pts);
80  avio_printf(pb, " --> ");
81  webvtt_write_time(pb, pkt->pts + pkt->duration);
82 
84  &settings_size);
85 
86  if (settings && settings_size > 0)
87  avio_printf(pb, " %.*s", settings_size, settings);
88 
89  avio_printf(pb, "\n");
90 
91  avio_write(pb, pkt->data, pkt->size);
92  avio_printf(pb, "\n");
93 
94  return 0;
95 }
96 
98  .name = "webvtt",
99  .long_name = NULL_IF_CONFIG_SMALL("WebVTT subtitle"),
100  .extensions = "vtt",
101  .mime_type = "text/vtt",
103  .subtitle_codec = AV_CODEC_ID_WEBVTT,
104  .write_header = webvtt_write_header,
105  .write_packet = webvtt_write_packet,
106 };
const char * s
Definition: avisynth_c.h:768
Bytestream IO Context.
Definition: avio.h:155
static int webvtt_write_header(AVFormatContext *ctx)
Definition: webvttenc.c:46
The optional first identifier line of a WebVTT cue.
Definition: avcodec.h:1553
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:4601
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: avcodec.h:4066
int size
Definition: avcodec.h:1658
static AVPacket pkt
#define AVFMT_TS_NONSTRICT
Format does not require strictly increasing timestamps, but they must still be monotonic.
Definition: avformat.h:496
This struct describes the properties of an encoded stream.
Definition: avcodec.h:4058
Format I/O context.
Definition: avformat.h:1349
uint8_t
int64_t duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: avcodec.h:1675
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1417
uint8_t * data
Definition: avcodec.h:1657
void avio_write(AVIOContext *s, const unsigned char *buf, int size)
Definition: aviobuf.c:205
#define av_log(a,...)
static void webvtt_write_time(AVIOContext *pb, int64_t millisec)
Definition: webvttenc.c:30
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
AVOutputFormat ff_webvtt_muxer
Definition: webvttenc.c:97
#define AVERROR(e)
Definition: error.h:43
uint8_t * av_packet_get_side_data(const AVPacket *pkt, enum AVPacketSideDataType type, int *size)
Get side information from packet.
Definition: avpacket.c:350
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:179
unsigned int nb_streams
Number of elements in AVFormatContext.streams.
Definition: avformat.h:1405
int void avio_flush(AVIOContext *s)
Force flushing of buffered data.
Definition: aviobuf.c:225
const char * name
Definition: avformat.h:524
AVFormatContext * ctx
Definition: movenc.c:48
static int webvtt_write_packet(AVFormatContext *ctx, AVPacket *pkt)
Definition: webvttenc.c:65
Stream structure.
Definition: avformat.h:889
AVIOContext * pb
I/O context.
Definition: avformat.h:1391
Main libavformat public API header.
The optional settings (rendering instructions) that immediately follow the timestamp specifier of a W...
Definition: avcodec.h:1559
#define AVFMT_VARIABLE_FPS
Format allows variable fps.
Definition: avformat.h:489
AVCodecParameters * codecpar
Definition: avformat.h:1252
float min
enum AVCodecID id
This structure stores compressed data.
Definition: avcodec.h:1634
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: avcodec.h:1650
int avio_printf(AVIOContext *s, const char *fmt,...) av_printf_format(2