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assenc.c
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1 /*
2  * SSA/ASS encoder
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_split.h"
26 #include "ass.h"
27 #include "libavutil/avstring.h"
28 #include "libavutil/internal.h"
29 #include "libavutil/mem.h"
30 
31 typedef struct {
32  int id; ///< current event id, ReadOrder field
34 
36 {
37  avctx->extradata = av_malloc(avctx->subtitle_header_size + 1);
38  if (!avctx->extradata)
39  return AVERROR(ENOMEM);
40  memcpy(avctx->extradata, avctx->subtitle_header, avctx->subtitle_header_size);
41  avctx->extradata_size = avctx->subtitle_header_size;
42  avctx->extradata[avctx->extradata_size] = 0;
43  return 0;
44 }
45 
46 static int ass_encode_frame(AVCodecContext *avctx,
47  unsigned char *buf, int bufsize,
48  const AVSubtitle *sub)
49 {
50  ASSEncodeContext *s = avctx->priv_data;
51  int i, len, total_len = 0;
52 
53  for (i=0; i<sub->num_rects; i++) {
54  char ass_line[2048];
55  const char *ass = sub->rects[i]->ass;
56 
57  if (sub->rects[i]->type != SUBTITLE_ASS) {
58  av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n");
59  return -1;
60  }
61 
62  if (strncmp(ass, "Dialogue: ", 10)) {
63  av_log(avctx, AV_LOG_ERROR, "AVSubtitle rectangle ass \"%s\""
64  " does not look like a SSA markup\n", ass);
65  return AVERROR_INVALIDDATA;
66  }
67 
68  if (avctx->codec->id == AV_CODEC_ID_ASS) {
69  long int layer;
70  char *p;
71 
72  if (i > 0) {
73  av_log(avctx, AV_LOG_ERROR, "ASS encoder supports only one "
74  "ASS rectangle field.\n");
75  return AVERROR_INVALIDDATA;
76  }
77 
78  ass += 10; // skip "Dialogue: "
79  /* parse Layer field. If it's a Marked field, the content
80  * will be "Marked=N" instead of the layer num, so we will
81  * have layer=0, which is fine. */
82  layer = strtol(ass, &p, 10);
83 
84 #define SKIP_ENTRY(ptr) do { \
85  char *sep = strchr(ptr, ','); \
86  if (sep) \
87  ptr = sep + 1; \
88 } while (0)
89 
90  SKIP_ENTRY(p); // skip layer or marked
91  SKIP_ENTRY(p); // skip start timestamp
92  SKIP_ENTRY(p); // skip end timestamp
93  snprintf(ass_line, sizeof(ass_line), "%d,%ld,%s", ++s->id, layer, p);
94  ass_line[strcspn(ass_line, "\r\n")] = 0;
95  ass = ass_line;
96  }
97  len = av_strlcpy(buf+total_len, ass, bufsize-total_len);
98 
99  if (len > bufsize-total_len-1) {
100  av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n");
101  return -1;
102  }
103 
104  total_len += len;
105  }
106 
107  return total_len;
108 }
109 
110 #if CONFIG_SSA_ENCODER
111 AVCodec ff_ssa_encoder = {
112  .name = "ssa",
113  .long_name = NULL_IF_CONFIG_SMALL("SSA (SubStation Alpha) subtitle"),
114  .type = AVMEDIA_TYPE_SUBTITLE,
115  .id = AV_CODEC_ID_SSA,
116  .init = ass_encode_init,
117  .encode_sub = ass_encode_frame,
118  .priv_data_size = sizeof(ASSEncodeContext),
119 };
120 #endif
121 
122 #if CONFIG_ASS_ENCODER
123 AVCodec ff_ass_encoder = {
124  .name = "ass",
125  .long_name = NULL_IF_CONFIG_SMALL("ASS (Advanced SubStation Alpha) subtitle"),
126  .type = AVMEDIA_TYPE_SUBTITLE,
127  .id = AV_CODEC_ID_ASS,
128  .init = ass_encode_init,
129  .encode_sub = ass_encode_frame,
130  .priv_data_size = sizeof(ASSEncodeContext),
131 };
132 #endif