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
162
163
164
|
/*
* MPEG-4 video frame extraction
* Copyright (c) 2003 Fabrice Bellard
* Copyright (c) 2003 Michael Niedermayer
*
* This file is part of FFmpeg.
*
* FFmpeg 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.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#define UNCHECKED_BITSTREAM_READER 1
#include "decode.h"
#include "parser.h"
#include "mpegvideo.h"
#include "mpeg4videodec.h"
#include "mpeg4videodefs.h"
struct Mp4vParseContext {
ParseContext pc;
Mpeg4DecContext dec_ctx;
int first_picture;
};
/**
* Find the end of the current frame in the bitstream.
* @return the position of the first byte of the next frame, or -1
*/
static int mpeg4_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
{
int vop_found, i;
uint32_t state;
vop_found = pc->frame_start_found;
state = pc->state;
i = 0;
if (!vop_found) {
for (i = 0; i < buf_size; i++) {
state = (state << 8) | buf[i];
if (state == VOP_STARTCODE) {
i++;
vop_found = 1;
break;
}
}
}
if (vop_found) {
/* EOF considered as end of frame */
if (buf_size == 0)
return 0;
for (; i < buf_size; i++) {
state = (state << 8) | buf[i];
if ((state & 0xFFFFFF00) == 0x100) {
if (state == SLICE_STARTCODE || state == EXT_STARTCODE)
continue;
pc->frame_start_found = 0;
pc->state = -1;
return i - 3;
}
}
}
pc->frame_start_found = vop_found;
pc->state = state;
return END_NOT_FOUND;
}
/* XXX: make it use less memory */
static int mpeg4_decode_header(AVCodecParserContext *s1, AVCodecContext *avctx,
const uint8_t *buf, int buf_size)
{
struct Mp4vParseContext *pc = s1->priv_data;
Mpeg4DecContext *dec_ctx = &pc->dec_ctx;
MpegEncContext *s = &dec_ctx->m;
GetBitContext gb1, *gb = &gb1;
int ret;
s->avctx = avctx;
s->current_picture_ptr = &s->current_picture;
if (avctx->extradata_size && pc->first_picture) {
init_get_bits(gb, avctx->extradata, avctx->extradata_size * 8);
ret = ff_mpeg4_decode_picture_header(dec_ctx, gb, 1, 1);
if (ret < 0)
av_log(avctx, AV_LOG_WARNING, "Failed to parse extradata\n");
}
init_get_bits(gb, buf, 8 * buf_size);
ret = ff_mpeg4_decode_picture_header(dec_ctx, gb, 0, 1);
if (s->width && (!avctx->width || !avctx->height ||
!avctx->coded_width || !avctx->coded_height)) {
ret = ff_set_dimensions(avctx, s->width, s->height);
if (ret < 0)
return ret;
}
if((s1->flags & PARSER_FLAG_USE_CODEC_TS) && s->avctx->framerate.num>0 && ret>=0){
av_assert1(s1->pts == AV_NOPTS_VALUE);
av_assert1(s1->dts == AV_NOPTS_VALUE);
s1->pts = av_rescale_q(s->time, (AVRational){1, s->avctx->framerate.num}, (AVRational){1, 1200000});
}
s1->pict_type = s->pict_type;
pc->first_picture = 0;
return ret;
}
static av_cold int mpeg4video_parse_init(AVCodecParserContext *s)
{
struct Mp4vParseContext *pc = s->priv_data;
pc->first_picture = 1;
pc->dec_ctx.m.quant_precision = 5;
pc->dec_ctx.m.slice_context_count = 1;
pc->dec_ctx.showed_packed_warning = 1;
return 0;
}
static int mpeg4video_parse(AVCodecParserContext *s,
AVCodecContext *avctx,
const uint8_t **poutbuf, int *poutbuf_size,
const uint8_t *buf, int buf_size)
{
ParseContext *pc = s->priv_data;
int next;
if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
next = buf_size;
} else {
next = mpeg4_find_frame_end(pc, buf, buf_size);
if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
*poutbuf = NULL;
*poutbuf_size = 0;
return buf_size;
}
}
mpeg4_decode_header(s, avctx, buf, buf_size);
*poutbuf = buf;
*poutbuf_size = buf_size;
return next;
}
const AVCodecParser ff_mpeg4video_parser = {
.codec_ids = { AV_CODEC_ID_MPEG4 },
.priv_data_size = sizeof(struct Mp4vParseContext),
.parser_init = mpeg4video_parse_init,
.parser_parse = mpeg4video_parse,
.parser_close = ff_parse_close,
};
|
