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
|
package mpeg
import (
"github.com/wader/fq/pkg/decode"
)
func annexBFindStartCode(d *decode.D) (int64, int64, error) {
offset, v, err := d.TryPeekFind(32, 8, -1, func(v uint64) bool {
return annexBDecodeStartCodeLen(v) > 0
})
return offset, annexBDecodeStartCodeLen(v), err
}
func annexBDecodeStartCodeLen(v uint64) int64 {
switch {
case v == 0x00_00_00_01:
return 4 * 8
case v&0xff_ff_ff_00 == 0x00_00_01_00:
return 3 * 8
default:
return 0
}
}
func annexBDecode(d *decode.D, format decode.Group) any {
currentOffset, currentPrefixLen, err := annexBFindStartCode(d)
// TODO: really restrict to 0?
if err != nil || currentOffset != 0 {
d.Errorf("could not find start code (first)")
}
for d.NotEnd() {
d.FieldRawLen("start_code", currentPrefixLen)
nextOffset, nextPrefixLen, err := annexBFindStartCode(d)
if err != nil {
nextOffset = d.Len() - d.Pos()
}
naluLen := nextOffset
d.FieldFormatLen("nalu", naluLen, &format, nil)
currentPrefixLen = nextPrefixLen
}
return nil
}
|
