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microdvddec.c
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1 /*
2  * MicroDVD subtitle demuxer
3  * Copyright (c) 2010 Aurelien Jacobs <aurel@gnuage.org>
4  * Copyright (c) 2012 Clément Bœsch <u pkh me>
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 "avformat.h"
24 #include "internal.h"
25 #include "subtitles.h"
26 #include "libavutil/intreadwrite.h"
27 #include "libavutil/opt.h"
28 
29 #define MAX_LINESIZE 2048
30 
31 
32 typedef struct {
33  const AVClass *class;
37 
38 
40 {
41  unsigned char c;
42  const uint8_t *ptr = p->buf;
43  int i;
44 
45  if (AV_RB24(ptr) == 0xEFBBBF)
46  ptr += 3; /* skip UTF-8 BOM */
47 
48  for (i=0; i<3; i++) {
49  if (sscanf(ptr, "{%*d}{}%c", &c) != 1 &&
50  sscanf(ptr, "{%*d}{%*d}%c", &c) != 1 &&
51  sscanf(ptr, "{DEFAULT}{}%c", &c) != 1)
52  return 0;
53  ptr += ff_subtitles_next_line(ptr);
54  }
55  return AVPROBE_SCORE_MAX;
56 }
57 
58 static int64_t get_pts(const char *buf)
59 {
60  int frame;
61  char c;
62 
63  if (sscanf(buf, "{%d}{%c", &frame, &c) == 2)
64  return frame;
65  return AV_NOPTS_VALUE;
66 }
67 
68 static int get_duration(const char *buf)
69 {
71 
72  if (sscanf(buf, "{%d}{%d}", &frame_start, &frame_end) == 2)
73  return frame_end - frame_start;
74  return -1;
75 }
76 
77 static const char *bom = "\xEF\xBB\xBF";
78 
80 {
81  AVRational pts_info = (AVRational){ 2997, 125 }; /* default: 23.976 fps */
82  MicroDVDContext *microdvd = s->priv_data;
83  AVStream *st = avformat_new_stream(s, NULL);
84  int i = 0;
85  char line_buf[MAX_LINESIZE];
86  int has_real_fps = 0;
87 
88  if (!st)
89  return AVERROR(ENOMEM);
90 
91  while (!url_feof(s->pb)) {
92  char *p;
93  AVPacket *sub;
94  int64_t pos = avio_tell(s->pb);
95  int len = ff_get_line(s->pb, line_buf, sizeof(line_buf));
96  char *line = line_buf;
97 
98  if (!strncmp(line, bom, 3))
99  line += 3;
100  p = line;
101 
102  if (!len)
103  break;
104  line[strcspn(line, "\r\n")] = 0;
105  if (i++ < 3) {
106  int frame;
107  double fps;
108  char c;
109 
110  if ((sscanf(line, "{%d}{}%6lf", &frame, &fps) == 2 ||
111  sscanf(line, "{%d}{%*d}%6lf", &frame, &fps) == 2)
112  && frame <= 1 && fps > 3 && fps < 100) {
113  pts_info = av_d2q(fps, 100000);
114  has_real_fps = 1;
115  }
116  if (!st->codec->extradata && sscanf(line, "{DEFAULT}{}%c", &c) == 1) {
117  st->codec->extradata = av_strdup(line + 11);
118  if (!st->codec->extradata)
119  return AVERROR(ENOMEM);
120  st->codec->extradata_size = strlen(st->codec->extradata) + 1;
121  continue;
122  }
123  }
124 #define SKIP_FRAME_ID \
125  p = strchr(p, '}'); \
126  if (!p) { \
127  av_log(s, AV_LOG_WARNING, "Invalid event \"%s\"" \
128  " at line %d\n", line, i); \
129  continue; \
130  } \
131  p++
134  if (!*p)
135  continue;
136  sub = ff_subtitles_queue_insert(&microdvd->q, p, strlen(p), 0);
137  if (!sub)
138  return AVERROR(ENOMEM);
139  sub->pos = pos;
140  sub->pts = get_pts(line);
141  sub->duration = get_duration(line);
142  }
143  ff_subtitles_queue_finalize(&microdvd->q);
144  if (has_real_fps) {
145  /* export the FPS info only if set in the file */
146  microdvd->frame_rate = pts_info;
147  } else if (microdvd->frame_rate.num) {
148  /* fallback on user specified frame rate */
149  pts_info = microdvd->frame_rate;
150  }
151  avpriv_set_pts_info(st, 64, pts_info.den, pts_info.num);
154  return 0;
155 }
156 
158 {
159  MicroDVDContext *microdvd = s->priv_data;
160  return ff_subtitles_queue_read_packet(&microdvd->q, pkt);
161 }
162 
163 static int microdvd_read_seek(AVFormatContext *s, int stream_index,
164  int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
165 {
166  MicroDVDContext *microdvd = s->priv_data;
167  return ff_subtitles_queue_seek(&microdvd->q, s, stream_index,
168  min_ts, ts, max_ts, flags);
169 }
170 
172 {
173  MicroDVDContext *microdvd = s->priv_data;
174  ff_subtitles_queue_clean(&microdvd->q);
175  return 0;
176 }
177 
178 
179 #define OFFSET(x) offsetof(MicroDVDContext, x)
180 #define SD AV_OPT_FLAG_SUBTITLE_PARAM|AV_OPT_FLAG_DECODING_PARAM
181 static const AVOption microdvd_options[] = {
182  { "subfps", "set the movie frame rate fallback", OFFSET(frame_rate), AV_OPT_TYPE_RATIONAL, {.dbl=0}, 0, INT_MAX, SD },
183  { NULL }
184 };
185 
186 static const AVClass microdvd_class = {
187  .class_name = "microdvddec",
188  .item_name = av_default_item_name,
189  .option = microdvd_options,
190  .version = LIBAVUTIL_VERSION_INT,
191 };
192 
194  .name = "microdvd",
195  .long_name = NULL_IF_CONFIG_SMALL("MicroDVD subtitle format"),
196  .priv_data_size = sizeof(MicroDVDContext),
200  .read_seek2 = microdvd_read_seek,
202  .priv_class = &microdvd_class,
203 };