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libavcodec
webvttdec.c
Go to the documentation of this file.
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/*
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* Copyright (c) 2012 Clément Bœsch
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* WebVTT subtitle decoder
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* @see http://dev.w3.org/html5/webvtt/
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* @todo need to support extended markups and cue settings
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*/
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#include "
avcodec.h
"
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#include "
ass.h
"
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#include "
libavutil/bprint.h
"
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static
const
struct
{
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const
char
*
from
;
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const
char
*
to
;
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}
webvtt_tag_replace
[] = {
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{
"<i>"
,
"{\\i1}"
}, {
"</i>"
,
"{\\i0}"
},
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{
"<b>"
,
"{\\b1}"
}, {
"</b>"
,
"{\\b0}"
},
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{
"<u>"
,
"{\\u1}"
}, {
"</u>"
,
"{\\u0}"
},
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{
"{"
,
"\\{"
}, {
"}"
,
"\\}"
},
// escape to avoid ASS markup conflicts
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};
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static
int
webvtt_event_to_ass
(
AVBPrint
*buf,
const
char
*p)
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{
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int
i, skip = 0;
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while
(*p) {
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for
(i = 0; i <
FF_ARRAY_ELEMS
(
webvtt_tag_replace
); i++) {
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const
char
*
from
=
webvtt_tag_replace
[i].from;
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const
size_t
len
= strlen(from);
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if
(!strncmp(p, from, len)) {
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av_bprintf
(buf,
"%s"
,
webvtt_tag_replace
[i].
to
);
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p +=
len
;
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break
;
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}
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}
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if
(!*p)
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break
;
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if
(*p ==
'<'
)
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skip = 1;
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else
if
(*p ==
'>'
)
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skip = 0;
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else
if
(p[0] ==
'\n'
&& p[1])
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av_bprintf
(buf,
"\\N"
);
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else
if
(!skip && *p !=
'\r'
)
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av_bprint_chars
(buf, *p, 1);
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p++;
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}
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av_bprintf
(buf,
"\r\n"
);
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return
0;
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}
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static
int
webvtt_decode_frame
(
AVCodecContext
*avctx,
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void
*
data
,
int
*got_sub_ptr,
AVPacket
*avpkt)
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{
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AVSubtitle
*sub =
data
;
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const
char
*ptr = avpkt->
data
;
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AVBPrint
buf;
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av_bprint_init
(&buf, 0,
AV_BPRINT_SIZE_UNLIMITED
);
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if
(ptr && avpkt->
size
> 0 && !
webvtt_event_to_ass
(&buf, ptr)) {
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int
ts_start =
av_rescale_q
(avpkt->
pts
, avctx->
time_base
, (
AVRational
){1,100});
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int
ts_duration = avpkt->
duration
!= -1 ?
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av_rescale_q
(avpkt->
duration
, avctx->
time_base
, (
AVRational
){1,100}) : -1;
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ff_ass_add_rect
(sub, buf.str, ts_start, ts_duration, 0);
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}
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*got_sub_ptr = sub->num_rects > 0;
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av_bprint_finalize
(&buf,
NULL
);
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return
avpkt->size;
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}
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AVCodec
ff_webvtt_decoder
= {
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.
name
=
"webvtt"
,
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.long_name =
NULL_IF_CONFIG_SMALL
(
"WebVTT subtitle"
),
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.type =
AVMEDIA_TYPE_SUBTITLE
,
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.id =
AV_CODEC_ID_WEBVTT
,
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.decode =
webvtt_decode_frame
,
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.init =
ff_ass_subtitle_header_default
,
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};
Generated on Sat May 25 2013 03:58:42 for FFmpeg by
1.8.2