libavcodec/assdec.c
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 /*
  * SSA/ASS decoder
  * Copyright (c) 2010  Aurelien Jacobs <aurel@gnuage.org>
  *
  * 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
  */
 
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 #include <string.h>
 
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 #include "avcodec.h"
 #include "ass.h"
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 #include "ass_split.h"
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 #include "libavutil/internal.h"
 #include "libavutil/mem.h"
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 static av_cold int ass_decode_init(AVCodecContext *avctx)
 {
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     avctx->subtitle_header = av_malloc(avctx->extradata_size + 1);
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     if (!avctx->subtitle_header)
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         return AVERROR(ENOMEM);
     memcpy(avctx->subtitle_header, avctx->extradata, avctx->extradata_size);
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     avctx->subtitle_header[avctx->extradata_size] = 0;
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     avctx->subtitle_header_size = avctx->extradata_size;
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     avctx->priv_data = ff_ass_split(avctx->extradata);
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     if(!avctx->priv_data)
         return -1;
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     return 0;
 }
 
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 static int ass_decode_close(AVCodecContext *avctx)
 {
     ff_ass_split_free(avctx->priv_data);
     avctx->priv_data = NULL;
     return 0;
 }
 
 #if CONFIG_SSA_DECODER
 static int ssa_decode_frame(AVCodecContext *avctx, void *data, int *got_sub_ptr,
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                             AVPacket *avpkt)
 {
     const char *ptr = avpkt->data;
     int len, size = avpkt->size;
 
     while (size > 0) {
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         int duration;
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         ASSDialog *dialog = ff_ass_split_dialog(avctx->priv_data, ptr, 0, NULL);
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         if (!dialog)
             return AVERROR_INVALIDDATA;
         duration = dialog->end - dialog->start;
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         len = ff_ass_add_rect(data, ptr, 0, duration, 1);
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         if (len < 0)
             return len;
         ptr  += len;
         size -= len;
     }
 
     *got_sub_ptr = avpkt->size > 0;
     return avpkt->size;
 }
 
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 AVCodec ff_ssa_decoder = {
     .name         = "ssa",
     .long_name    = NULL_IF_CONFIG_SMALL("SSA (SubStation Alpha) subtitle"),
     .type         = AVMEDIA_TYPE_SUBTITLE,
     .id           = AV_CODEC_ID_SSA,
     .init         = ass_decode_init,
     .decode       = ssa_decode_frame,
     .close        = ass_decode_close,
 };
 #endif
 
 #if CONFIG_ASS_DECODER
 static int ass_decode_frame(AVCodecContext *avctx, void *data, int *got_sub_ptr,
                             AVPacket *avpkt)
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 {
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     int ret;
     AVSubtitle *sub = data;
     const char *ptr = avpkt->data;
     static const AVRational ass_tb = {1, 100};
     const int ts_start    = av_rescale_q(avpkt->pts,      avctx->time_base, ass_tb);
     const int ts_duration = av_rescale_q(avpkt->duration, avctx->time_base, ass_tb);
 
     if (avpkt->size <= 0)
         return avpkt->size;
 
     ret = ff_ass_add_rect(sub, ptr, ts_start, ts_duration, 2);
     if (ret < 0) {
         if (ret == AVERROR_INVALIDDATA)
             av_log(avctx, AV_LOG_ERROR, "Invalid ASS packet\n");
         return ret;
     }
 
     *got_sub_ptr = avpkt->size > 0;
     return avpkt->size;
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 }
 
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 AVCodec ff_ass_decoder = {
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     .name         = "ass",
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     .long_name    = NULL_IF_CONFIG_SMALL("ASS (Advanced SubStation Alpha) subtitle"),
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     .type         = AVMEDIA_TYPE_SUBTITLE,
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     .id           = AV_CODEC_ID_ASS,
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     .init         = ass_decode_init,
     .decode       = ass_decode_frame,
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     .close        = ass_decode_close,
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 };
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 #endif