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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;
34     FFDemuxSubtitlesQueue q;
35     AVRational frame_rate;
36 } MicroDVDContext;
37 
38 
microdvd_probe(const AVProbeData * p)39 static int microdvd_probe(const AVProbeData *p)
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 
get_pts(const char * buf)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 
get_duration(const char * buf)68 static int64_t get_duration(const char *buf)
69 {
70     int frame_start, frame_end;
71 
72     if (sscanf(buf, "{%d}{%d}", &frame_start, &frame_end) == 2)
73         return frame_end - (int64_t)frame_start;
74     return -1;
75 }
76 
77 static const char *bom = "\xEF\xBB\xBF";
78 
microdvd_read_header(AVFormatContext * s)79 static int microdvd_read_header(AVFormatContext *s)
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, ret;
85     char line_buf[MAX_LINESIZE];
86     int has_real_fps = 0;
87 
88     if (!st)
89         return AVERROR(ENOMEM);
90 
91     while (!avio_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         int64_t pts;
98 
99         if (!strncmp(line, bom, 3))
100             line += 3;
101         p = line;
102 
103         if (!len)
104             break;
105         line[strcspn(line, "\r\n")] = 0;
106         if (!*p)
107             continue;
108         if (i++ < 3) {
109             int frame;
110             double fps;
111             char c;
112 
113             if ((sscanf(line, "{%d}{}%6lf",    &frame, &fps) == 2 ||
114                  sscanf(line, "{%d}{%*d}%6lf", &frame, &fps) == 2)
115                 && frame <= 1 && fps > 3 && fps < 100) {
116                 pts_info = av_d2q(fps, 100000);
117                 has_real_fps = 1;
118                 continue;
119             }
120             if (!st->codecpar->extradata && sscanf(line, "{DEFAULT}{}%c", &c) == 1) {
121                 int size = strlen(line + 11);
122                 ret = ff_alloc_extradata(st->codecpar, size);
123                 if (ret < 0)
124                     goto fail;
125                 memcpy(st->codecpar->extradata, line + 11, size);
126                 continue;
127             }
128         }
129 #define SKIP_FRAME_ID                                       \
130     p = strchr(p, '}');                                     \
131     if (!p) {                                               \
132         av_log(s, AV_LOG_WARNING, "Invalid event \"%s\""    \
133                " at line %d\n", line, i);                   \
134         continue;                                           \
135     }                                                       \
136     p++
137         SKIP_FRAME_ID;
138         SKIP_FRAME_ID;
139         if (!*p)
140             continue;
141         pts = get_pts(line);
142         if (pts == AV_NOPTS_VALUE)
143             continue;
144         sub = ff_subtitles_queue_insert(&microdvd->q, p, strlen(p), 0);
145         if (!sub) {
146             ret = AVERROR(ENOMEM);
147             goto fail;
148         }
149         sub->pos = pos;
150         sub->pts = pts;
151         sub->duration = get_duration(line);
152     }
153     ff_subtitles_queue_finalize(s, &microdvd->q);
154     if (has_real_fps) {
155         /* export the FPS info only if set in the file */
156         microdvd->frame_rate = pts_info;
157     } else if (microdvd->frame_rate.num) {
158         /* fallback on user specified frame rate */
159         pts_info = microdvd->frame_rate;
160     }
161     avpriv_set_pts_info(st, 64, pts_info.den, pts_info.num);
162     st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
163     st->codecpar->codec_id   = AV_CODEC_ID_MICRODVD;
164     return 0;
165 fail:
166     ff_subtitles_queue_clean(&microdvd->q);
167     return ret;
168 }
169 
microdvd_read_packet(AVFormatContext * s,AVPacket * pkt)170 static int microdvd_read_packet(AVFormatContext *s, AVPacket *pkt)
171 {
172     MicroDVDContext *microdvd = s->priv_data;
173     return ff_subtitles_queue_read_packet(&microdvd->q, pkt);
174 }
175 
microdvd_read_seek(AVFormatContext * s,int stream_index,int64_t min_ts,int64_t ts,int64_t max_ts,int flags)176 static int microdvd_read_seek(AVFormatContext *s, int stream_index,
177                              int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
178 {
179     MicroDVDContext *microdvd = s->priv_data;
180     return ff_subtitles_queue_seek(&microdvd->q, s, stream_index,
181                                    min_ts, ts, max_ts, flags);
182 }
183 
microdvd_read_close(AVFormatContext * s)184 static int microdvd_read_close(AVFormatContext *s)
185 {
186     MicroDVDContext *microdvd = s->priv_data;
187     ff_subtitles_queue_clean(&microdvd->q);
188     return 0;
189 }
190 
191 
192 #define OFFSET(x) offsetof(MicroDVDContext, x)
193 #define SD AV_OPT_FLAG_SUBTITLE_PARAM|AV_OPT_FLAG_DECODING_PARAM
194 static const AVOption microdvd_options[] = {
195     { "subfps", "set the movie frame rate fallback", OFFSET(frame_rate), AV_OPT_TYPE_RATIONAL, {.dbl=0}, 0, INT_MAX, SD },
196     { NULL }
197 };
198 
199 static const AVClass microdvd_class = {
200     .class_name = "microdvddec",
201     .item_name  = av_default_item_name,
202     .option     = microdvd_options,
203     .version    = LIBAVUTIL_VERSION_INT,
204 };
205 
206 AVInputFormat ff_microdvd_demuxer = {
207     .name           = "microdvd",
208     .long_name      = NULL_IF_CONFIG_SMALL("MicroDVD subtitle format"),
209     .priv_data_size = sizeof(MicroDVDContext),
210     .read_probe     = microdvd_probe,
211     .read_header    = microdvd_read_header,
212     .read_packet    = microdvd_read_packet,
213     .read_seek2     = microdvd_read_seek,
214     .read_close     = microdvd_read_close,
215     .priv_class     = &microdvd_class,
216 };
217