FFmpeg
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filmstripdec.c
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1 /*
2  * Adobe Filmstrip demuxer
3  * Copyright (c) 2010 Peter Ross
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 /**
23  * @file
24  * Adobe Filmstrip demuxer
25  */
26 
27 #include "libavutil/intreadwrite.h"
28 #include "avformat.h"
29 #include "internal.h"
30 
31 #define RAND_TAG MKBETAG('R','a','n','d')
32 
33 typedef struct {
34  int leading;
36 
38 {
40  AVIOContext *pb = s->pb;
41  AVStream *st;
42 
43  if (!s->pb->seekable)
44  return AVERROR(EIO);
45 
46  avio_seek(pb, avio_size(pb) - 36, SEEK_SET);
47  if (avio_rb32(pb) != RAND_TAG) {
48  av_log(s, AV_LOG_ERROR, "magic number not found\n");
49  return AVERROR_INVALIDDATA;
50  }
51 
52  st = avformat_new_stream(s, NULL);
53  if (!st)
54  return AVERROR(ENOMEM);
55 
56  st->nb_frames = avio_rb32(pb);
57  if (avio_rb16(pb) != 0) {
58  av_log_ask_for_sample(s, "unsupported packing method\n");
59  return AVERROR_PATCHWELCOME;
60  }
61 
62  avio_skip(pb, 2);
66  st->codec->codec_tag = 0; /* no fourcc */
67  st->codec->width = avio_rb16(pb);
68  st->codec->height = avio_rb16(pb);
69  film->leading = avio_rb16(pb);
70  avpriv_set_pts_info(st, 64, 1, avio_rb16(pb));
71 
72  avio_seek(pb, 0, SEEK_SET);
73 
74  return 0;
75 }
76 
78  AVPacket *pkt)
79 {
81  AVStream *st = s->streams[0];
82 
83  if (url_feof(s->pb))
84  return AVERROR(EIO);
85  pkt->dts = avio_tell(s->pb) / (st->codec->width * (st->codec->height + film->leading) * 4);
86  pkt->size = av_get_packet(s->pb, pkt, st->codec->width * st->codec->height * 4);
87  avio_skip(s->pb, st->codec->width * film->leading * 4);
88  if (pkt->size < 0)
89  return pkt->size;
90  pkt->flags |= AV_PKT_FLAG_KEY;
91  return 0;
92 }
93 
94 static int read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
95 {
96  AVStream *st = s->streams[stream_index];
97  if (avio_seek(s->pb, FFMAX(timestamp, 0) * st->codec->width * st->codec->height * 4, SEEK_SET) < 0)
98  return -1;
99  return 0;
100 }
101 
103  .name = "filmstrip",
104  .long_name = NULL_IF_CONFIG_SMALL("Adobe Filmstrip"),
105  .priv_data_size = sizeof(FilmstripDemuxContext),
108  .read_seek = read_seek,
109  .extensions = "flm",
110 };