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
|
/*
* Apple MJPEG-B decoder
* Copyright (c) 2002 Alex Beregszaszi
*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* Apple MJPEG-B decoder.
*/
#include "avcodec.h"
#include "mjpeg.h"
#include "mjpegdec.h"
static uint32_t read_offs(AVCodecContext *avctx, GetBitContext *gb, uint32_t size, const char *err_msg){
uint32_t offs= get_bits_long(gb, 32);
if(offs >= size){
av_log(avctx, AV_LOG_WARNING, err_msg, offs, size);
return 0;
}
return offs;
}
static int mjpegb_decode_frame(AVCodecContext *avctx,
void *data, int *data_size,
AVPacket *avpkt)
{
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
MJpegDecodeContext *s = avctx->priv_data;
const uint8_t *buf_end, *buf_ptr;
AVFrame *picture = data;
GetBitContext hgb; /* for the header */
uint32_t dqt_offs, dht_offs, sof_offs, sos_offs, second_field_offs;
uint32_t field_size, sod_offs;
buf_ptr = buf;
buf_end = buf + buf_size;
read_header:
/* reset on every SOI */
s->restart_interval = 0;
s->restart_count = 0;
s->mjpb_skiptosod = 0;
init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8);
skip_bits(&hgb, 32); /* reserved zeros */
if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g'))
{
av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n");
return AVERROR_INVALIDDATA;
}
field_size = get_bits_long(&hgb, 32); /* field size */
av_log(avctx, AV_LOG_DEBUG, "field size: 0x%x\n", field_size);
skip_bits(&hgb, 32); /* padded field size */
second_field_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "second_field_offs is %d and size is %d\n");
av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%x\n", second_field_offs);
dqt_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dqt is %d and size is %d\n");
av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%x\n", dqt_offs);
if (dqt_offs)
{
init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8);
s->start_code = DQT;
ff_mjpeg_decode_dqt(s);
}
dht_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dht is %d and size is %d\n");
av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%x\n", dht_offs);
if (dht_offs)
{
init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8);
s->start_code = DHT;
ff_mjpeg_decode_dht(s);
}
sof_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%x\n", sof_offs);
if (sof_offs)
{
init_get_bits(&s->gb, buf_ptr+sof_offs, (buf_end - (buf_ptr+sof_offs))*8);
s->start_code = SOF0;
if (ff_mjpeg_decode_sof(s) < 0)
return -1;
}
sos_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sos is %d and size is %d\n");
av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%x\n", sos_offs);
sod_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%x\n", sod_offs);
if (sos_offs)
{
// init_get_bits(&s->gb, buf+sos_offs, (buf_end - (buf+sos_offs))*8);
init_get_bits(&s->gb, buf_ptr+sos_offs, field_size*8);
s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16));
s->start_code = SOS;
ff_mjpeg_decode_sos(s, NULL, NULL);
}
if (s->interlaced) {
s->bottom_field ^= 1;
/* if not bottom field, do not output image yet */
if (s->bottom_field != s->interlace_polarity && second_field_offs)
{
buf_ptr = buf + second_field_offs;
second_field_offs = 0;
goto read_header;
}
}
//XXX FIXME factorize, this looks very similar to the EOI code
*picture= *s->picture_ptr;
*data_size = sizeof(AVFrame);
if(!s->lossless){
picture->quality= FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2]);
picture->qstride= 0;
picture->qscale_table= s->qscale_table;
memset(picture->qscale_table, picture->quality, (s->width+15)/16);
if(avctx->debug & FF_DEBUG_QP)
av_log(avctx, AV_LOG_DEBUG, "QP: %d\n", picture->quality);
picture->quality*= FF_QP2LAMBDA;
}
return buf_size;
}
AVCodec ff_mjpegb_decoder = {
"mjpegb",
AVMEDIA_TYPE_VIDEO,
CODEC_ID_MJPEGB,
sizeof(MJpegDecodeContext),
ff_mjpeg_decode_init,
NULL,
ff_mjpeg_decode_end,
mjpegb_decode_frame,
CODEC_CAP_DR1,
NULL,
.max_lowres = 3,
.long_name = NULL_IF_CONFIG_SMALL("Apple MJPEG-B"),
};
|
