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ffmpeg / libavformat / assenc.c @ 2912e87a

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/*
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 * SSA/ASS muxer
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 * Copyright (c) 2008 Michael Niedermayer
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 *
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 * This file is part of Libav.
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 *
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 * Libav 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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 * Libav 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 Libav; 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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#include "avformat.h"
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typedef struct ASSContext{
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    unsigned int extra_index;
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}ASSContext;
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static int write_header(AVFormatContext *s)
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{
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    ASSContext *ass = s->priv_data;
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    AVCodecContext *avctx= s->streams[0]->codec;
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    uint8_t *last= NULL;
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    if(s->nb_streams != 1 || avctx->codec_id != CODEC_ID_SSA){
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        av_log(s, AV_LOG_ERROR, "Exactly one ASS/SSA stream is needed.\n");
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        return -1;
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    }
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    while(ass->extra_index < avctx->extradata_size){
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        uint8_t *p  = avctx->extradata + ass->extra_index;
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        uint8_t *end= strchr(p, '\n');
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        if(!end) end= avctx->extradata + avctx->extradata_size;
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        else     end++;
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        avio_write(s->pb, p, end-p);
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        ass->extra_index += end-p;
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        if(last && !memcmp(last, "[Events]", 8))
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            break;
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        last=p;
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    }
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    avio_flush(s->pb);
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    return 0;
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}
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static int write_packet(AVFormatContext *s, AVPacket *pkt)
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{
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    avio_write(s->pb, pkt->data, pkt->size);
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    avio_flush(s->pb);
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    return 0;
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}
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static int write_trailer(AVFormatContext *s)
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{
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    ASSContext *ass = s->priv_data;
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    AVCodecContext *avctx= s->streams[0]->codec;
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    avio_write(s->pb, avctx->extradata      + ass->extra_index,
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                      avctx->extradata_size - ass->extra_index);
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    avio_flush(s->pb);
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    return 0;
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}
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AVOutputFormat ff_ass_muxer = {
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    .name           = "ass",
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    .long_name      = NULL_IF_CONFIG_SMALL("Advanced SubStation Alpha subtitle format"),
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    .mime_type      = "text/x-ssa",
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    .extensions     = "ass,ssa",
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    .priv_data_size = sizeof(ASSContext),
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    .subtitle_codec = CODEC_ID_SSA,
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    .write_header   = write_header,
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    .write_packet   = write_packet,
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    .write_trailer  = write_trailer,
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    .flags          = AVFMT_GLOBALHEADER | AVFMT_NOTIMESTAMPS,
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};