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https://github.com/wader/fq.git
synced 2024-12-24 22:05:31 +03:00
48 lines
1.0 KiB
Go
48 lines
1.0 KiB
Go
package mpeg
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import (
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"github.com/wader/fq/pkg/decode"
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)
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func annexBFindStartCode(d *decode.D) (int64, int64, error) {
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offset, v, err := d.TryPeekFind(32, 8, -1, func(v uint64) bool {
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return annexBDecodeStartCodeLen(v) > 0
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})
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return offset, annexBDecodeStartCodeLen(v), err
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}
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func annexBDecodeStartCodeLen(v uint64) int64 {
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switch {
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case v == 0x00_00_00_01:
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return 4 * 8
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case v&0xff_ff_ff_00 == 0x00_00_01_00:
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return 3 * 8
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default:
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return 0
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}
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}
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func annexBDecode(d *decode.D, _ interface{}, format decode.Group) interface{} {
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currentOffset, currentPrefixLen, err := annexBFindStartCode(d)
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// TODO: really restrict to 0?
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if err != nil || currentOffset != 0 {
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d.Errorf("could not find start code (first)")
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}
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for d.NotEnd() {
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d.FieldRawLen("start_code", currentPrefixLen)
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nextOffset, nextPrefixLen, err := annexBFindStartCode(d)
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if err != nil {
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nextOffset = d.Len() - d.Pos()
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}
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naluLen := nextOffset
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d.FieldFormatLen("nalu", naluLen, format, nil)
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currentPrefixLen = nextPrefixLen
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}
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return nil
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}
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