FFmpeg
Main Page
Related Pages
Modules
Namespaces
Data Structures
Files
Examples
File List
Globals
All
Data Structures
Namespaces
Files
Functions
Variables
Typedefs
Enumerations
Enumerator
Macros
Groups
Pages
libavformat
bit.c
Go to the documentation of this file.
1
/*
2
* G.729 bit format muxer and demuxer
3
* Copyright (c) 2007-2008 Vladimir Voroshilov
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
#include "
avformat.h
"
22
#include "
internal.h
"
23
#include "
libavcodec/get_bits.h
"
24
#include "
libavcodec/put_bits.h
"
25
26
#define MAX_FRAME_SIZE 10
27
28
#define SYNC_WORD 0x6b21
29
#define BIT_0 0x7f
30
#define BIT_1 0x81
31
32
static
int
probe
(
AVProbeData
*p)
33
{
34
int
i, j;
35
36
if
(p->
buf_size
< 0x40)
37
return
0;
38
39
for
(i=0; i+3<p->
buf_size
&& i< 10*0x50; ){
40
if
(
AV_RL16
(&p->
buf
[0]) !=
SYNC_WORD
)
41
return
0;
42
j=
AV_RL16
(&p->
buf
[2]);
43
if
(j!=0x40 && j!=0x50)
44
return
0;
45
i+=j;
46
}
47
return
AVPROBE_SCORE_EXTENSION
;
48
}
49
50
static
int
read_header
(
AVFormatContext
*
s
)
51
{
52
AVStream
* st;
53
54
st=
avformat_new_stream
(s, NULL);
55
if
(!st)
56
return
AVERROR
(ENOMEM);
57
58
st->
codec
->
codec_type
=
AVMEDIA_TYPE_AUDIO
;
59
st->
codec
->
codec_id
=
AV_CODEC_ID_G729
;
60
st->
codec
->
sample_rate
=8000;
61
st->
codec
->
block_align
= 16;
62
st->
codec
->
channels
=1;
63
64
avpriv_set_pts_info
(st, 64, 1, 100);
65
return
0;
66
}
67
68
static
int
read_packet
(
AVFormatContext
*
s
,
69
AVPacket
*
pkt
)
70
{
71
AVIOContext
*pb = s->
pb
;
72
PutBitContext
pbo;
73
uint16_t
buf
[8 *
MAX_FRAME_SIZE
+ 2];
74
int
packet_size;
75
uint16_t*
src
=
buf
;
76
int
i, j,
ret
;
77
int64_t pos=
avio_tell
(pb);
78
79
if
(
url_feof
(pb))
80
return
AVERROR_EOF
;
81
82
avio_rl16
(pb);
// sync word
83
packet_size =
avio_rl16
(pb) / 8;
84
if
(packet_size >
MAX_FRAME_SIZE
)
85
return
AVERROR_INVALIDDATA
;
86
87
ret =
avio_read
(pb, (
uint8_t
*)buf, (8 * packet_size) *
sizeof
(uint16_t));
88
if
(ret<0)
89
return
ret
;
90
if
(ret != 8 * packet_size *
sizeof
(uint16_t))
91
return
AVERROR
(EIO);
92
93
if
(
av_new_packet
(pkt, packet_size) < 0)
94
return
AVERROR
(ENOMEM);
95
96
init_put_bits
(&pbo, pkt->
data
, packet_size);
97
for
(j=0; j < packet_size; j++)
98
for
(i=0; i<8;i++)
99
put_bits
(&pbo,1,
AV_RL16
(src++) ==
BIT_1
? 1 : 0);
100
101
flush_put_bits
(&pbo);
102
103
pkt->
duration
=1;
104
pkt->
pos
= pos;
105
return
0;
106
}
107
108
AVInputFormat
ff_bit_demuxer
= {
109
.
name
=
"bit"
,
110
.long_name =
NULL_IF_CONFIG_SMALL
(
"G.729 BIT file format"
),
111
.read_probe =
probe
,
112
.read_header =
read_header
,
113
.read_packet =
read_packet
,
114
.extensions =
"bit"
,
115
};
116
117
#if CONFIG_MUXERS
118
static
int
write_header
(
AVFormatContext
*
s
)
119
{
120
AVCodecContext
*enc = s->
streams
[0]->
codec
;
121
122
enc->
codec_id
=
AV_CODEC_ID_G729
;
123
enc->
channels
= 1;
124
enc->
bits_per_coded_sample
= 16;
125
enc->
block_align
= (enc->
bits_per_coded_sample
* enc->
channels
) >> 3;
126
127
return
0;
128
}
129
130
static
int
write_packet
(
AVFormatContext
*
s
,
AVPacket
*
pkt
)
131
{
132
AVIOContext
*pb = s->
pb
;
133
GetBitContext
gb;
134
int
i;
135
136
avio_wl16
(pb,
SYNC_WORD
);
137
avio_wl16
(pb, 8 * 10);
138
139
init_get_bits
(&gb, pkt->
data
, 8*10);
140
for
(i=0; i< 8 * 10; i++)
141
avio_wl16
(pb,
get_bits1
(&gb) ?
BIT_1
:
BIT_0
);
142
143
return
0;
144
}
145
146
AVOutputFormat
ff_bit_muxer = {
147
.
name
=
"bit"
,
148
.long_name =
NULL_IF_CONFIG_SMALL
(
"G.729 BIT file format"
),
149
.mime_type =
"audio/bit"
,
150
.extensions =
"bit"
,
151
.audio_codec =
AV_CODEC_ID_G729
,
152
.video_codec =
AV_CODEC_ID_NONE
,
153
.write_header =
write_header
,
154
.write_packet =
write_packet
,
155
};
156
#endif
Generated on Wed Jul 10 2013 23:48:11 for FFmpeg by
1.8.2