Main Page
Related Pages
Modules
Data Structures
Files
Examples
File List
Globals
libavcodec
wnv1.c
Go to the documentation of this file.
1
/*
2
* Winnov WNV1 codec
3
* Copyright (c) 2005 Konstantin Shishkov
4
*
5
* This file is part of Libav.
6
*
7
* Libav 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
* Libav 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 Libav; if not, write to the Free Software
19
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20
*/
21
27
#include "
avcodec.h
"
28
#include "
get_bits.h
"
29
#include "
libavutil/common.h
"
30
31
32
typedef
struct
WNV1Context
{
33
AVCodecContext
*
avctx
;
34
AVFrame
pic
;
35
36
int
shift
;
37
GetBitContext
gb
;
38
}
WNV1Context
;
39
40
static
const
uint16_t
code_tab
[16][2]={
41
{0x1FD,9}, {0xFD,8}, {0x7D,7}, {0x3D,6}, {0x1D,5}, {0x0D,4}, {0x005,3},
42
{0x000,1},
43
{0x004,3}, {0x0C,4}, {0x1C,5}, {0x3C,6}, {0x7C,7}, {0xFC,8}, {0x1FC,9}, {0xFF,8}
44
};
45
46
#define CODE_VLC_BITS 9
47
static
VLC
code_vlc
;
48
49
/* returns modified base_value */
50
static
inline
int
wnv1_get_code
(
WNV1Context
*w,
int
base_value)
51
{
52
int
v
=
get_vlc2
(&w->
gb
, code_vlc.
table
,
CODE_VLC_BITS
, 1);
53
54
if
(v==15)
55
return
av_reverse
[
get_bits
(&w->
gb
, 8 - w->
shift
) ];
56
else
57
return
base_value + ((v - 7)<<w->
shift
);
58
}
59
60
static
int
decode_frame
(
AVCodecContext
*avctx,
61
void
*
data
,
int
*data_size,
62
AVPacket
*avpkt)
63
{
64
const
uint8_t *buf = avpkt->
data
;
65
int
buf_size = avpkt->
size
;
66
WNV1Context
*
const
l = avctx->
priv_data
;
67
AVFrame
*
const
p= (
AVFrame
*)&l->
pic
;
68
unsigned
char
*
Y
,*
U
,*
V
;
69
int
i, j;
70
int
prev_y = 0, prev_u = 0, prev_v = 0;
71
uint8_t *rbuf;
72
73
rbuf =
av_malloc
(buf_size +
FF_INPUT_BUFFER_PADDING_SIZE
);
74
if
(!rbuf){
75
av_log
(avctx,
AV_LOG_ERROR
,
"Cannot allocate temporary buffer\n"
);
76
return
-1;
77
}
78
79
if
(p->
data
[0])
80
avctx->
release_buffer
(avctx, p);
81
82
p->
reference
= 0;
83
if
(avctx->
get_buffer
(avctx, p) < 0){
84
av_log
(avctx,
AV_LOG_ERROR
,
"get_buffer() failed\n"
);
85
av_free
(rbuf);
86
return
-1;
87
}
88
p->
key_frame
= 1;
89
90
for
(i=8; i<buf_size; i++)
91
rbuf[i]=
av_reverse
[ buf[i] ];
92
init_get_bits
(&l->
gb
, rbuf+8, (buf_size-8)*8);
93
94
if
(buf[2] >> 4 == 6)
95
l->
shift
= 2;
96
else
{
97
l->
shift
= 8 - (buf[2] >> 4);
98
if
(l->
shift
> 4) {
99
av_log_ask_for_sample
(avctx,
"Unknown WNV1 frame header value %i\n"
,
100
buf[2] >> 4);
101
l->
shift
= 4;
102
}
103
if
(l->
shift
< 1) {
104
av_log_ask_for_sample
(avctx,
"Unknown WNV1 frame header value %i\n"
,
105
buf[2] >> 4);
106
l->
shift
= 1;
107
}
108
}
109
110
Y = p->
data
[0];
111
U
= p->
data
[1];
112
V
= p->
data
[2];
113
for
(j = 0; j < avctx->
height
; j++) {
114
for
(i = 0; i < avctx->
width
/ 2; i++) {
115
Y[i * 2] =
wnv1_get_code
(l, prev_y);
116
prev_u =
U
[i] =
wnv1_get_code
(l, prev_u);
117
prev_y = Y[(i * 2) + 1] =
wnv1_get_code
(l, Y[i * 2]);
118
prev_v =
V
[i] =
wnv1_get_code
(l, prev_v);
119
}
120
Y += p->
linesize
[0];
121
U
+= p->
linesize
[1];
122
V
+= p->
linesize
[2];
123
}
124
125
126
*data_size =
sizeof
(
AVFrame
);
127
*(
AVFrame
*)data = l->
pic
;
128
av_free
(rbuf);
129
130
return
buf_size;
131
}
132
133
static
av_cold
int
decode_init
(
AVCodecContext
*avctx){
134
WNV1Context
*
const
l = avctx->
priv_data
;
135
static
VLC_TYPE
code_table[1 <<
CODE_VLC_BITS
][2];
136
137
l->
avctx
= avctx;
138
avctx->
pix_fmt
=
PIX_FMT_YUV422P
;
139
140
code_vlc.
table
= code_table;
141
code_vlc.
table_allocated
= 1 <<
CODE_VLC_BITS
;
142
init_vlc
(&code_vlc,
CODE_VLC_BITS
, 16,
143
&
code_tab
[0][1], 4, 2,
144
&
code_tab
[0][0], 4, 2,
INIT_VLC_USE_NEW_STATIC
);
145
146
return
0;
147
}
148
149
static
av_cold
int
decode_end
(
AVCodecContext
*avctx){
150
WNV1Context
*
const
l = avctx->
priv_data
;
151
AVFrame
*pic = &l->
pic
;
152
153
if
(pic->
data
[0])
154
avctx->
release_buffer
(avctx, pic);
155
156
return
0;
157
}
158
159
AVCodec
ff_wnv1_decoder
= {
160
.
name
=
"wnv1"
,
161
.type =
AVMEDIA_TYPE_VIDEO
,
162
.id =
CODEC_ID_WNV1
,
163
.priv_data_size =
sizeof
(
WNV1Context
),
164
.
init
=
decode_init
,
165
.
close
=
decode_end
,
166
.
decode
=
decode_frame
,
167
.capabilities =
CODEC_CAP_DR1
,
168
.long_name =
NULL_IF_CONFIG_SMALL
(
"Winnov WNV1"
),
169
};