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/*
* Copyright (c) 2012 Clément Bœsch
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* WebVTT subtitle demuxer
* @see http://dev.w3.org/html5/webvtt/
*/
#include "avformat.h"
#include "internal.h"
#include "subtitles.h"
#include "libavutil/bprint.h"
#include "libavutil/intreadwrite.h"
typedef struct {
FFDemuxSubtitlesQueue q;
} WebVTTContext;
static int webvtt_probe(AVProbeData *p)
{
const uint8_t *ptr = p->buf;
if (AV_RB24(ptr) == 0xEFBBBF)
ptr += 3; /* skip UTF-8 BOM */
if (!strncmp(ptr, "WEBVTT", 6) &&
(!ptr[6] || strchr("\n\r\t ", ptr[6])))
return AVPROBE_SCORE_MAX;
return 0;
}
static int64_t read_ts(const char *s)
{
int hh, mm, ss, ms;
if (sscanf(s, "%u:%u:%u.%u", &hh, &mm, &ss, &ms) == 4) return (hh*3600LL + mm*60LL + ss) * 1000LL + ms;
if (sscanf(s, "%u:%u.%u", &mm, &ss, &ms) == 3) return ( mm*60LL + ss) * 1000LL + ms;
return AV_NOPTS_VALUE;
}
static int64_t extract_cue(AVBPrint *buf, AVIOContext *pb)
{
int prev_chr_is_eol = 0;
int64_t pos = avio_tell(pb);
av_bprint_clear(buf);
for (;;) {
char c = avio_r8(pb);
if (!c)
break;
if (c == '\r' || c == '\n') {
if (prev_chr_is_eol)
break;
prev_chr_is_eol = (c == '\n');
} else
prev_chr_is_eol = 0;
if (c != '\r')
av_bprint_chars(buf, c, 1);
}
av_bprint_chars(buf, '\0', 1);
return pos;
}
static int webvtt_read_header(AVFormatContext *s)
{
WebVTTContext *webvtt = s->priv_data;
AVBPrint header, cue;
int res = 0;
AVStream *st = avformat_new_stream(s, NULL);
if (!st)
return AVERROR(ENOMEM);
avpriv_set_pts_info(st, 64, 1, 1000);
st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
st->codec->codec_id = AV_CODEC_ID_WEBVTT;
av_bprint_init(&header, 0, AV_BPRINT_SIZE_UNLIMITED);
av_bprint_init(&cue, 0, AV_BPRINT_SIZE_UNLIMITED);
for (;;) {
int i, len;
int64_t pos = extract_cue(&cue, s->pb);
AVPacket *sub;
const char *p = cue.str;
const char *identifier = p;
//const char *settings = NULL;
int64_t ts_start, ts_end;
if (!*p) // EOF
break;
/* ignore header chunk */
if (!strncmp(p, "\xEF\xBB\xBFWEBVTT", 9) ||
!strncmp(p, "WEBVTT", 6))
continue;
/* optional cue identifier (can be a number like in SRT or some kind of
* chaptering id), silently skip it */
for (i = 0; p[i] && p[i] != '\n'; i++) {
if (!strncmp(p + i, "-->", 3)) {
identifier = NULL;
break;
}
}
if (identifier)
p += strcspn(p, "\n");
/* cue timestamps */
if ((ts_start = read_ts(p)) == AV_NOPTS_VALUE)
break;
if (!(p = strstr(p, "-->")))
break;
p += 3;
do p++; while (*p == ' ' || *p == '\t');
if ((ts_end = read_ts(p)) == AV_NOPTS_VALUE)
break;
/* optional cue settings, TODO: store in side_data */
p += strcspn(p, "\n\t ");
while (*p == '\t' || *p == ' ')
p++;
if (*p != '\n') {
//settings = p;
p += strcspn(p, "\n");
}
if (*p == '\n')
p++;
/* create packet */
len = cue.str + cue.len - p - 1;
sub = ff_subtitles_queue_insert(&webvtt->q, p, len, 0);
if (!sub) {
res = AVERROR(ENOMEM);
goto end;
}
sub->pos = pos;
sub->pts = ts_start;
sub->duration = ts_end - ts_start;
}
ff_subtitles_queue_finalize(&webvtt->q);
end:
av_bprint_finalize(&cue, NULL);
av_bprint_finalize(&header, NULL);
return res;
}
static int webvtt_read_packet(AVFormatContext *s, AVPacket *pkt)
{
WebVTTContext *webvtt = s->priv_data;
return ff_subtitles_queue_read_packet(&webvtt->q, pkt);
}
static int webvtt_read_seek(AVFormatContext *s, int stream_index,
int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
{
WebVTTContext *webvtt = s->priv_data;
return ff_subtitles_queue_seek(&webvtt->q, s, stream_index,
min_ts, ts, max_ts, flags);
}
static int webvtt_read_close(AVFormatContext *s)
{
WebVTTContext *webvtt = s->priv_data;
ff_subtitles_queue_clean(&webvtt->q);
return 0;
}
AVInputFormat ff_webvtt_demuxer = {
.name = "webvtt",
.long_name = NULL_IF_CONFIG_SMALL("WebVTT subtitle"),
.priv_data_size = sizeof(WebVTTContext),
.read_probe = webvtt_probe,
.read_header = webvtt_read_header,
.read_packet = webvtt_read_packet,
.read_seek2 = webvtt_read_seek,
.read_close = webvtt_read_close,
.extensions = "vtt",
};
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