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libavcodec
wnv1.c
Go to the documentation of this file.
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/*
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* Winnov WNV1 codec
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* Copyright (c) 2005 Konstantin Shishkov
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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27
#include "
avcodec.h
"
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#include "
get_bits.h
"
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#include "
libavutil/common.h
"
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typedef
struct
WNV1Context
{
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AVCodecContext
*
avctx
;
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AVFrame
pic
;
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int
shift
;
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GetBitContext
gb
;
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}
WNV1Context
;
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static
const
uint16_t
code_tab
[16][2]={
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{0x1FD,9}, {0xFD,8}, {0x7D,7}, {0x3D,6}, {0x1D,5}, {0x0D,4}, {0x005,3},
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{0x000,1},
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{0x004,3}, {0x0C,4}, {0x1C,5}, {0x3C,6}, {0x7C,7}, {0xFC,8}, {0x1FC,9}, {0xFF,8}
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};
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#define CODE_VLC_BITS 9
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static
VLC
code_vlc
;
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/* returns modified base_value */
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static
inline
int
wnv1_get_code
(
WNV1Context
*w,
int
base_value)
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{
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int
v
=
get_vlc2
(&w->
gb
, code_vlc.
table
,
CODE_VLC_BITS
, 1);
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if
(v==15)
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return
av_reverse
[
get_bits
(&w->
gb
, 8 - w->
shift
) ];
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else
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return
base_value + ((v - 7)<<w->
shift
);
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}
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static
int
decode_frame
(
AVCodecContext
*avctx,
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void
*
data
,
int
*data_size,
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AVPacket
*avpkt)
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{
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const
uint8_t *buf = avpkt->
data
;
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int
buf_size = avpkt->
size
;
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WNV1Context
*
const
l = avctx->
priv_data
;
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AVFrame
*
const
p= (
AVFrame
*)&l->
pic
;
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unsigned
char
*
Y
,*
U
,*
V
;
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int
i, j;
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int
prev_y = 0, prev_u = 0, prev_v = 0;
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uint8_t *rbuf;
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if (buf_size < 8) {
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av_log
(avctx,
AV_LOG_ERROR
,
"Packet is too short\n"
);
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return
AVERROR_INVALIDDATA
;
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}
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rbuf =
av_malloc
(buf_size +
FF_INPUT_BUFFER_PADDING_SIZE
);
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if
(!rbuf){
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av_log
(avctx,
AV_LOG_ERROR
,
"Cannot allocate temporary buffer\n"
);
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return
-1;
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}
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if
(p->
data
[0])
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avctx->
release_buffer
(avctx, p);
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p->
reference
= 0;
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if
(avctx->
get_buffer
(avctx, p) < 0){
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av_log
(avctx,
AV_LOG_ERROR
,
"get_buffer() failed\n"
);
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av_free
(rbuf);
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return
-1;
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}
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p->
key_frame
= 1;
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for
(i=8; i<buf_size; i++)
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rbuf[i]=
av_reverse
[ buf[i] ];
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init_get_bits
(&l->
gb
, rbuf+8, (buf_size-8)*8);
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if
(buf[2] >> 4 == 6)
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l->
shift
= 2;
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else
{
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l->
shift
= 8 - (buf[2] >> 4);
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if
(l->
shift
> 4) {
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av_log_ask_for_sample
(avctx,
"Unknown WNV1 frame header value %i\n"
,
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buf[2] >> 4);
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l->
shift
= 4;
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}
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if
(l->
shift
< 1) {
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av_log_ask_for_sample
(avctx,
"Unknown WNV1 frame header value %i\n"
,
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buf[2] >> 4);
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l->
shift
= 1;
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}
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}
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Y = p->
data
[0];
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U
= p->
data
[1];
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V
= p->
data
[2];
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for
(j = 0; j < avctx->
height
; j++) {
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for
(i = 0; i < avctx->
width
/ 2; i++) {
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Y[i * 2] =
wnv1_get_code
(l, prev_y);
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prev_u =
U
[i] =
wnv1_get_code
(l, prev_u);
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prev_y = Y[(i * 2) + 1] =
wnv1_get_code
(l, Y[i * 2]);
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prev_v =
V
[i] =
wnv1_get_code
(l, prev_v);
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}
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Y += p->
linesize
[0];
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U
+= p->
linesize
[1];
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V
+= p->
linesize
[2];
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}
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*data_size =
sizeof
(
AVFrame
);
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*(
AVFrame
*)data = l->
pic
;
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av_free
(rbuf);
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return
buf_size;
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}
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static
av_cold
int
decode_init
(
AVCodecContext
*avctx){
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WNV1Context
*
const
l = avctx->
priv_data
;
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static
VLC_TYPE
code_table[1 <<
CODE_VLC_BITS
][2];
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l->
avctx
= avctx;
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avctx->
pix_fmt
=
PIX_FMT_YUV422P
;
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code_vlc.
table
= code_table;
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code_vlc.
table_allocated
= 1 <<
CODE_VLC_BITS
;
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init_vlc
(&code_vlc,
CODE_VLC_BITS
, 16,
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&
code_tab
[0][1], 4, 2,
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&
code_tab
[0][0], 4, 2,
INIT_VLC_USE_NEW_STATIC
);
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return
0;
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}
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static
av_cold
int
decode_end
(
AVCodecContext
*avctx){
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WNV1Context
*
const
l = avctx->
priv_data
;
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AVFrame
*pic = &l->
pic
;
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if
(pic->
data
[0])
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avctx->
release_buffer
(avctx, pic);
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return
0;
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}
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AVCodec
ff_wnv1_decoder
= {
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.
name
=
"wnv1"
,
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.type =
AVMEDIA_TYPE_VIDEO
,
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.id =
CODEC_ID_WNV1
,
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.priv_data_size =
sizeof
(
WNV1Context
),
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.
init
=
decode_init
,
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.
close
=
decode_end
,
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.
decode
=
decode_frame
,
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.capabilities =
CODEC_CAP_DR1
,
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.long_name =
NULL_IF_CONFIG_SMALL
(
"Winnov WNV1"
),
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};