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assdec.c
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1 /*
2  * SSA/ASS demuxer
3  * Copyright (c) 2008 Michael Niedermayer
4  * Copyright (c) 2014 Clément Bœsch
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 #include <stdint.h>
24 
25 #include "avformat.h"
26 #include "internal.h"
27 #include "subtitles.h"
28 #include "libavcodec/internal.h"
29 #include "libavutil/bprint.h"
30 
31 typedef struct ASSContext {
33  unsigned readorder;
34 } ASSContext;
35 
36 static int ass_probe(AVProbeData *p)
37 {
38  char buf[13];
39  FFTextReader tr;
40  ff_text_init_buf(&tr, p->buf, p->buf_size);
41 
42  ff_text_read(&tr, buf, sizeof(buf));
43 
44  if (!memcmp(buf, "[Script Info]", 13))
45  return AVPROBE_SCORE_MAX;
46 
47  return 0;
48 }
49 
51 {
52  ASSContext *ass = s->priv_data;
54  return 0;
55 }
56 
57 static int read_dialogue(ASSContext *ass, AVBPrint *dst, const uint8_t *p,
58  int64_t *start, int *duration)
59 {
60  int pos = 0;
61  int64_t end;
62  int hh1, mm1, ss1, ms1;
63  int hh2, mm2, ss2, ms2;
64 
65  if (sscanf(p, "Dialogue: %*[^,],%d:%d:%d%*c%d,%d:%d:%d%*c%d,%n",
66  &hh1, &mm1, &ss1, &ms1,
67  &hh2, &mm2, &ss2, &ms2, &pos) >= 8 && pos > 0) {
68 
69  /* This is not part of the sscanf itself in order to handle an actual
70  * number (which would be the Layer) or the form "Marked=N" (which is
71  * the old SSA field, now replaced by Layer, and will lead to Layer
72  * being 0 here). */
73  const int layer = atoi(p + 10);
74 
75  end = (hh2*3600LL + mm2*60LL + ss2) * 100LL + ms2;
76  *start = (hh1*3600LL + mm1*60LL + ss1) * 100LL + ms1;
77  *duration = end - *start;
78 
79  av_bprint_clear(dst);
80  av_bprintf(dst, "%u,%d,%s", ass->readorder++, layer, p + pos);
81 
82  /* right strip the buffer */
83  while (dst->len > 0 &&
84  dst->str[dst->len - 1] == '\r' ||
85  dst->str[dst->len - 1] == '\n')
86  dst->str[--dst->len] = 0;
87  return 0;
88  }
89  return -1;
90 }
91 
92 static int64_t get_line(AVBPrint *buf, FFTextReader *tr)
93 {
94  int64_t pos = ff_text_pos(tr);
95 
96  av_bprint_clear(buf);
97  for (;;) {
98  char c = ff_text_r8(tr);
99  if (!c)
100  break;
101  av_bprint_chars(buf, c, 1);
102  if (c == '\n')
103  break;
104  }
105  return pos;
106 }
107 
109 {
110  ASSContext *ass = s->priv_data;
111  AVBPrint header, line, rline;
112  int res = 0;
113  AVStream *st;
114  FFTextReader tr;
115  ff_text_init_avio(&tr, s->pb);
116 
117  st = avformat_new_stream(s, NULL);
118  if (!st)
119  return AVERROR(ENOMEM);
120  avpriv_set_pts_info(st, 64, 1, 100);
123 
127 
128  for (;;) {
129  int64_t pos = get_line(&line, &tr);
130  int64_t ts_start = AV_NOPTS_VALUE;
131  int duration = -1;
132  AVPacket *sub;
133 
134  if (!line.str[0]) // EOF
135  break;
136 
137  if (read_dialogue(ass, &rline, line.str, &ts_start, &duration) < 0) {
138  av_bprintf(&header, "%s", line.str);
139  continue;
140  }
141  sub = ff_subtitles_queue_insert(&ass->q, rline.str, rline.len, 0);
142  if (!sub) {
143  res = AVERROR(ENOMEM);
144  goto end;
145  }
146  sub->pos = pos;
147  sub->pts = ts_start;
148  sub->duration = duration;
149  }
150 
151  res = avpriv_bprint_to_extradata(st->codec, &header);
152  if (res < 0)
153  goto end;
154 
156 
157 end:
158  av_bprint_finalize(&header, NULL);
159  av_bprint_finalize(&line, NULL);
160  av_bprint_finalize(&rline, NULL);
161  return res;
162 }
163 
165 {
166  ASSContext *ass = s->priv_data;
167  return ff_subtitles_queue_read_packet(&ass->q, pkt);
168 }
169 
170 static int ass_read_seek(AVFormatContext *s, int stream_index,
171  int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
172 {
173  ASSContext *ass = s->priv_data;
174  return ff_subtitles_queue_seek(&ass->q, s, stream_index,
175  min_ts, ts, max_ts, flags);
176 }
177 
179  .name = "ass",
180  .long_name = NULL_IF_CONFIG_SMALL("SSA (SubStation Alpha) subtitle"),
181  .priv_data_size = sizeof(ASSContext),
186  .read_seek2 = ass_read_seek,
187 };