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libavformat
c93.c
Go to the documentation of this file.
1
/*
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* Interplay C93 demuxer
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* Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
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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
8
* modify it under the terms of the GNU Lesser General Public
9
* 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
15
* 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
19
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "
avformat.h
"
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#include "
internal.h
"
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#include "
voc.h
"
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#include "
libavutil/intreadwrite.h
"
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27
typedef
struct
{
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uint16_t
index
;
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uint8_t
length
;
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uint8_t
frames
;
31
}
C93BlockRecord
;
32
33
typedef
struct
{
34
VocDecContext
voc
;
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36
C93BlockRecord
block_records[512];
37
int
current_block
;
38
39
uint32_t frame_offsets[32];
40
int
current_frame
;
41
int
next_pkt_is_audio
;
42
43
AVStream
*
audio
;
44
}
C93DemuxContext
;
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46
static
int
probe
(
AVProbeData
*p)
47
{
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int
i;
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int
index
= 1;
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if
(p->
buf_size
< 16)
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return
0;
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for
(i = 0; i < 16; i += 4) {
53
if
(
AV_RL16
(p->
buf
+ i) != index || !p->
buf
[i + 2] || !p->
buf
[i + 3])
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return
0;
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index += p->
buf
[i + 2];
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}
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return
AVPROBE_SCORE_MAX
;
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}
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static
int
read_header
(
AVFormatContext
*s,
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AVFormatParameters
*ap)
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{
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AVStream
*video;
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AVIOContext
*pb = s->
pb
;
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C93DemuxContext
*c93 = s->
priv_data
;
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int
i;
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int
framecount = 0;
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for
(i = 0; i < 512; i++) {
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c93->
block_records
[i].
index
=
avio_rl16
(pb);
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c93->
block_records
[i].
length
=
avio_r8
(pb);
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c93->
block_records
[i].
frames
=
avio_r8
(pb);
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if
(c93->
block_records
[i].
frames
> 32) {
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av_log
(s,
AV_LOG_ERROR
,
"too many frames in block\n"
);
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return
AVERROR_INVALIDDATA
;
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}
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framecount += c93->
block_records
[i].
frames
;
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}
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/* Audio streams are added if audio packets are found */
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s->
ctx_flags
|=
AVFMTCTX_NOHEADER
;
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video =
avformat_new_stream
(s,
NULL
);
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if
(!video)
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return
AVERROR
(ENOMEM);
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video->
codec
->
codec_type
=
AVMEDIA_TYPE_VIDEO
;
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video->
codec
->
codec_id
=
CODEC_ID_C93
;
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video->
codec
->
width
= 320;
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video->
codec
->
height
= 192;
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/* 4:3 320x200 with 8 empty lines */
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video->
sample_aspect_ratio
= (
AVRational
) { 5, 6 };
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avpriv_set_pts_info
(video, 64, 2, 25);
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video->
nb_frames
= framecount;
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video->
duration
= framecount;
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video->
start_time
= 0;
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c93->
current_block
= 0;
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c93->
current_frame
= 0;
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c93->
next_pkt_is_audio
= 0;
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return
0;
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}
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#define C93_HAS_PALETTE 0x01
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#define C93_FIRST_FRAME 0x02
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static
int
read_packet
(
AVFormatContext
*s,
AVPacket
*pkt)
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{
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AVIOContext
*pb = s->
pb
;
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C93DemuxContext
*c93 = s->
priv_data
;
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C93BlockRecord
*br = &c93->
block_records
[c93->
current_block
];
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int
datasize;
113
int
ret, i;
114
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if
(c93->
next_pkt_is_audio
) {
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c93->
current_frame
++;
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c93->
next_pkt_is_audio
= 0;
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datasize =
avio_rl16
(pb);
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if
(datasize > 42) {
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if
(!c93->
audio
) {
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c93->
audio
=
avformat_new_stream
(s,
NULL
);
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if
(!c93->
audio
)
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return
AVERROR
(ENOMEM);
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c93->
audio
->
codec
->
codec_type
=
AVMEDIA_TYPE_AUDIO
;
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}
126
avio_skip
(pb, 26);
/* VOC header */
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ret =
voc_get_packet
(s, pkt, c93->
audio
, datasize - 26);
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if
(ret > 0) {
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pkt->
stream_index
= 1;
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pkt->
flags
|=
AV_PKT_FLAG_KEY
;
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return
ret;
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}
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}
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}
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if
(c93->
current_frame
>= br->
frames
) {
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if
(c93->
current_block
>= 511 || !br[1].
length
)
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return
AVERROR
(EIO);
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br++;
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c93->
current_block
++;
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c93->
current_frame
= 0;
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}
142
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if
(c93->
current_frame
== 0) {
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avio_seek
(pb, br->
index
* 2048, SEEK_SET);
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for
(i = 0; i < 32; i++) {
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c93->
frame_offsets
[i] =
avio_rl32
(pb);
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}
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}
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150
avio_seek
(pb,br->
index
* 2048 +
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c93->
frame_offsets
[c93->
current_frame
], SEEK_SET);
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datasize =
avio_rl16
(pb);
/* video frame size */
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ret =
av_new_packet
(pkt, datasize + 768 + 1);
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if
(ret < 0)
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return
ret;
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pkt->
data
[0] = 0;
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pkt->
size
= datasize + 1;
159
160
ret =
avio_read
(pb, pkt->
data
+ 1, datasize);
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if
(ret < datasize) {
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ret =
AVERROR
(EIO);
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goto
fail;
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}
165
166
datasize =
avio_rl16
(pb);
/* palette size */
167
if
(datasize) {
168
if
(datasize != 768) {
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av_log
(s,
AV_LOG_ERROR
,
"invalid palette size %u\n"
, datasize);
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ret =
AVERROR_INVALIDDATA
;
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goto
fail;
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}
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pkt->
data
[0] |=
C93_HAS_PALETTE
;
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ret =
avio_read
(pb, pkt->
data
+ pkt->
size
, datasize);
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if
(ret < datasize) {
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ret =
AVERROR
(EIO);
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goto
fail;
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}
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pkt->
size
+= 768;
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}
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pkt->
stream_index
= 0;
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c93->
next_pkt_is_audio
= 1;
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/* only the first frame is guaranteed to not reference previous frames */
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if
(c93->
current_block
== 0 && c93->
current_frame
== 0) {
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pkt->
flags
|=
AV_PKT_FLAG_KEY
;
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pkt->
data
[0] |=
C93_FIRST_FRAME
;
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}
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return
0;
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191
fail:
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av_free_packet
(pkt);
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return
ret;
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}
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AVInputFormat
ff_c93_demuxer
= {
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.
name
=
"c93"
,
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.long_name =
NULL_IF_CONFIG_SMALL
(
"Interplay C93"
),
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.priv_data_size =
sizeof
(
C93DemuxContext
),
200
.
read_probe
=
probe
,
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.
read_header
=
read_header
,
202
.
read_packet
=
read_packet
,
203
};