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  1. /*
  2.  * SSA/ASS decoder
  3.  * Copyright (c) 2010  Aurelien Jacobs <aurel@gnuage.org>
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  7.  * FFmpeg is free software; you can redistribute it and/or
  8.  * modify it under the terms of the GNU Lesser General Public
  9.  * License as published by the Free Software Foundation; either
  10.  * version 2.1 of the License, or (at your option) any later version.
  11.  *
  12.  * FFmpeg is distributed in the hope that it will be useful,
  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15.  * Lesser General Public License for more details.
  16.  *
  17.  * You should have received a copy of the GNU Lesser General Public
  18.  * License along with FFmpeg; if not, write to the Free Software
  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20.  */
  21.  
  22. #include <string.h>
  23.  
  24. #include "avcodec.h"
  25. #include "ass.h"
  26. #include "ass_split.h"
  27. #include "libavutil/internal.h"
  28. #include "libavutil/mem.h"
  29.  
  30. static av_cold int ass_decode_init(AVCodecContext *avctx)
  31. {
  32.     avctx->subtitle_header = av_malloc(avctx->extradata_size + 1);
  33.     if (!avctx->subtitle_header)
  34.         return AVERROR(ENOMEM);
  35.     memcpy(avctx->subtitle_header, avctx->extradata, avctx->extradata_size);
  36.     avctx->subtitle_header[avctx->extradata_size] = 0;
  37.     avctx->subtitle_header_size = avctx->extradata_size;
  38.     avctx->priv_data = ff_ass_split(avctx->extradata);
  39.     if(!avctx->priv_data)
  40.         return -1;
  41.     return 0;
  42. }
  43.  
  44. static int ass_decode_close(AVCodecContext *avctx)
  45. {
  46.     ff_ass_split_free(avctx->priv_data);
  47.     avctx->priv_data = NULL;
  48.     return 0;
  49. }
  50.  
  51. #if CONFIG_SSA_DECODER
  52. static int ssa_decode_frame(AVCodecContext *avctx, void *data, int *got_sub_ptr,
  53.                             AVPacket *avpkt)
  54. {
  55.     const char *ptr = avpkt->data;
  56.     int len, size = avpkt->size;
  57.  
  58.     while (size > 0) {
  59.         int duration;
  60.         ASSDialog *dialog = ff_ass_split_dialog(avctx->priv_data, ptr, 0, NULL);
  61.         if (!dialog)
  62.             return AVERROR_INVALIDDATA;
  63.         duration = dialog->end - dialog->start;
  64.         len = ff_ass_add_rect(data, ptr, 0, duration, 1);
  65.         if (len < 0)
  66.             return len;
  67.         ptr  += len;
  68.         size -= len;
  69.     }
  70.  
  71.     *got_sub_ptr = avpkt->size > 0;
  72.     return avpkt->size;
  73. }
  74.  
  75. AVCodec ff_ssa_decoder = {
  76.     .name         = "ssa",
  77.     .long_name    = NULL_IF_CONFIG_SMALL("SSA (SubStation Alpha) subtitle"),
  78.     .type         = AVMEDIA_TYPE_SUBTITLE,
  79.     .id           = AV_CODEC_ID_SSA,
  80.     .init         = ass_decode_init,
  81.     .decode       = ssa_decode_frame,
  82.     .close        = ass_decode_close,
  83. };
  84. #endif
  85.  
  86. #if CONFIG_ASS_DECODER
  87. static int ass_decode_frame(AVCodecContext *avctx, void *data, int *got_sub_ptr,
  88.                             AVPacket *avpkt)
  89. {
  90.     int ret;
  91.     AVSubtitle *sub = data;
  92.     const char *ptr = avpkt->data;
  93.     static const AVRational ass_tb = {1, 100};
  94.     const int ts_start    = av_rescale_q(avpkt->pts,      avctx->time_base, ass_tb);
  95.     const int ts_duration = av_rescale_q(avpkt->duration, avctx->time_base, ass_tb);
  96.  
  97.     if (avpkt->size <= 0)
  98.         return avpkt->size;
  99.  
  100.     ret = ff_ass_add_rect(sub, ptr, ts_start, ts_duration, 2);
  101.     if (ret < 0) {
  102.         if (ret == AVERROR_INVALIDDATA)
  103.             av_log(avctx, AV_LOG_ERROR, "Invalid ASS packet\n");
  104.         return ret;
  105.     }
  106.  
  107.     *got_sub_ptr = avpkt->size > 0;
  108.     return avpkt->size;
  109. }
  110.  
  111. AVCodec ff_ass_decoder = {
  112.     .name         = "ass",
  113.     .long_name    = NULL_IF_CONFIG_SMALL("ASS (Advanced SubStation Alpha) subtitle"),
  114.     .type         = AVMEDIA_TYPE_SUBTITLE,
  115.     .id           = AV_CODEC_ID_ASS,
  116.     .init         = ass_decode_init,
  117.     .decode       = ass_decode_frame,
  118.     .close        = ass_decode_close,
  119. };
  120. #endif
  121.