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assdec.c
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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 
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 {
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