Alexey Khit
60 lines
1.1 KiB
Go
60 lines
1.1 KiB
Go
package mpegts
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import (
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"time"
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)
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const (
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PacketSize = 188
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SyncByte = 0x47
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)
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const (
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StreamTypeH264 = 0x1B
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StreamTypePCMA = 0x90
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)
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type Packet struct {
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StreamType byte
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PTS time.Duration
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DTS time.Duration
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Payload []byte
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}
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// PES - Packetized Elementary Stream
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type PES struct {
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StreamType byte
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StreamID byte
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Payload []byte
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}
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func (p *PES) Packet() *Packet {
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// parse Optional PES header
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const minHeaderSize = 3
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pkt := &Packet{StreamType: p.StreamType}
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// fist byte also flags
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flags := p.Payload[1]
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hSize := p.Payload[2] // optional fields
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const hasPTS = 0b1000_0000
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if flags&hasPTS != 0 {
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pkt.PTS = ParseTime(p.Payload[minHeaderSize:])
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const hasDTS = 0b0100_0000
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if flags&hasDTS != 0 {
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pkt.DTS = ParseTime(p.Payload[minHeaderSize+5:])
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}
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}
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pkt.Payload = p.Payload[minHeaderSize+hSize:]
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return pkt
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}
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func ParseTime(b []byte) time.Duration {
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ts := (uint64(b[0]) >> 1 & 0x7 << 30) | (uint64(b[1]) << 22) | (uint64(b[2]) >> 1 & 0x7F << 15) | (uint64(b[3]) << 7) | (uint64(b[4]) >> 1 & 0x7F)
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return time.Duration(ts)
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}
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