1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
|
/*
* mtv demuxer
* Copyright (c) 2006 Reynaldo H. Verdejo Pinochet
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file libavformat/mtv.c
* MTV demuxer.
*/
#include "libavutil/bswap.h"
#include "libavutil/intreadwrite.h"
#include "avformat.h"
#define MTV_ASUBCHUNK_DATA_SIZE 500
#define MTV_HEADER_SIZE 512
#define MTV_AUDIO_PADDING_SIZE 12
#define AUDIO_SAMPLING_RATE 44100
#define VIDEO_SID 0
#define AUDIO_SID 1
typedef struct MTVDemuxContext {
unsigned int file_size; ///< filesize, not always right
unsigned int segments; ///< number of 512 byte segments
unsigned int audio_identifier; ///< 'MP3' on all files I have seen
unsigned int audio_br; ///< bitrate of audio chanel (mp3)
unsigned int img_colorfmt; ///< frame colorfmt rgb 565/555
unsigned int img_bpp; ///< frame bits per pixel
unsigned int img_width; //
unsigned int img_height; //
unsigned int img_segment_size; ///< size of image segment
unsigned int video_fps; //
unsigned int full_segment_size;
} MTVDemuxContext;
static int mtv_probe(AVProbeData *p)
{
/* Magic is 'AMV' */
if(*(p->buf) != 'A' || *(p->buf+1) != 'M' || *(p->buf+2) != 'V')
return 0;
/* Check for nonzero in bpp and (width|height) header fields */
if(!(p->buf[51] && AV_RL16(&p->buf[52]) | AV_RL16(&p->buf[54])))
return 0;
/* If width or height are 0 then imagesize header field should not */
if(!AV_RL16(&p->buf[52]) || !AV_RL16(&p->buf[54]))
{
if(!!AV_RL16(&p->buf[56]))
return AVPROBE_SCORE_MAX/2;
else
return 0;
}
return AVPROBE_SCORE_MAX;
}
static int mtv_read_header(AVFormatContext *s, AVFormatParameters *ap)
{
MTVDemuxContext *mtv = s->priv_data;
ByteIOContext *pb = s->pb;
AVStream *st;
unsigned int audio_subsegments;
url_fskip(pb, 3);
mtv->file_size = get_le32(pb);
mtv->segments = get_le32(pb);
url_fskip(pb, 32);
mtv->audio_identifier = get_le24(pb);
mtv->audio_br = get_le16(pb);
mtv->img_colorfmt = get_le24(pb);
mtv->img_bpp = get_byte(pb);
mtv->img_width = get_le16(pb);
mtv->img_height = get_le16(pb);
mtv->img_segment_size = get_le16(pb);
/* Calculate width and height if missing from header */
if(!mtv->img_width)
mtv->img_width=mtv->img_segment_size / (mtv->img_bpp>>3)
/ mtv->img_height;
if(!mtv->img_height)
mtv->img_height=mtv->img_segment_size / (mtv->img_bpp>>3)
/ mtv->img_width;
url_fskip(pb, 4);
audio_subsegments = get_le16(pb);
mtv->full_segment_size =
audio_subsegments * (MTV_AUDIO_PADDING_SIZE + MTV_ASUBCHUNK_DATA_SIZE) +
mtv->img_segment_size;
mtv->video_fps = (mtv->audio_br / 4) / audio_subsegments;
// FIXME Add sanity check here
// all systems go! init decoders
// video - raw rgb565
st = av_new_stream(s, VIDEO_SID);
if(!st)
return AVERROR(ENOMEM);
av_set_pts_info(st, 64, 1, mtv->video_fps);
st->codec->codec_type = CODEC_TYPE_VIDEO;
st->codec->codec_id = CODEC_ID_RAWVIDEO;
st->codec->codec_tag = MKTAG('R', 'G', 'B', mtv->img_bpp);
st->codec->width = mtv->img_width;
st->codec->height = mtv->img_height;
st->codec->bits_per_coded_sample = mtv->img_bpp;
st->codec->sample_rate = mtv->video_fps;
st->codec->extradata = av_strdup("BottomUp");
st->codec->extradata_size = 9;
// audio - mp3
st = av_new_stream(s, AUDIO_SID);
if(!st)
return AVERROR(ENOMEM);
av_set_pts_info(st, 64, 1, AUDIO_SAMPLING_RATE);
st->codec->codec_type = CODEC_TYPE_AUDIO;
st->codec->codec_id = CODEC_ID_MP3;
st->codec->bit_rate = mtv->audio_br;
st->need_parsing = AVSTREAM_PARSE_FULL;
// Jump over header
if(url_fseek(pb, MTV_HEADER_SIZE, SEEK_SET) != MTV_HEADER_SIZE)
return AVERROR(EIO);
return 0;
}
static int mtv_read_packet(AVFormatContext *s, AVPacket *pkt)
{
MTVDemuxContext *mtv = s->priv_data;
ByteIOContext *pb = s->pb;
int ret;
#if !HAVE_BIGENDIAN
int i;
#endif
if((url_ftell(pb) - s->data_offset + mtv->img_segment_size) % mtv->full_segment_size)
{
url_fskip(pb, MTV_AUDIO_PADDING_SIZE);
ret = av_get_packet(pb, pkt, MTV_ASUBCHUNK_DATA_SIZE);
if(ret != MTV_ASUBCHUNK_DATA_SIZE)
return AVERROR(EIO);
pkt->pos -= MTV_AUDIO_PADDING_SIZE;
pkt->stream_index = AUDIO_SID;
}else
{
ret = av_get_packet(pb, pkt, mtv->img_segment_size);
if(ret != mtv->img_segment_size)
return AVERROR(EIO);
#if !HAVE_BIGENDIAN
/* pkt->data is GGGRRRR BBBBBGGG
* and we need RRRRRGGG GGGBBBBB
* for PIX_FMT_RGB565 so here we
* just swap bytes as they come
*/
for(i=0;i<mtv->img_segment_size/2;i++)
*((uint16_t *)pkt->data+i) = bswap_16(*((uint16_t *)pkt->data+i));
#endif
pkt->stream_index = VIDEO_SID;
}
return ret;
}
AVInputFormat mtv_demuxer = {
"MTV",
NULL_IF_CONFIG_SMALL("MTV format"),
sizeof(MTVDemuxContext),
mtv_probe,
mtv_read_header,
mtv_read_packet,
};
|
