Add mpegts Reader

2023-02-13 15:45:26 +03:00
parent a22c33fd4e
commit 830baafffe
3 changed files with 275 additions and 0 deletions
@@ -0,0 +1,59 @@
+package mpegts
+
+import (
+	"time"
+)
+
+const (
+	PacketSize = 188
+	SyncByte   = 0x47
+)
+
+const (
+	StreamTypeH264 = 0x1B
+	StreamTypePCMA = 0x90
+)
+
+type Packet struct {
+	StreamType byte
+	PTS        time.Duration
+	DTS        time.Duration
+	Payload    []byte
+}
+
+// PES - Packetized Elementary Stream
+type PES struct {
+	StreamType byte
+	StreamID   byte
+	Payload    []byte
+}
+
+func (p *PES) Packet() *Packet {
+	// parse Optional PES header
+	const minHeaderSize = 3
+
+	pkt := &Packet{StreamType: p.StreamType}
+
+	// fist byte also flags
+	flags := p.Payload[1]
+	hSize := p.Payload[2] // optional fields
+
+	const hasPTS = 0b1000_0000
+	if flags&hasPTS != 0 {
+		pkt.PTS = ParseTime(p.Payload[minHeaderSize:])
+
+		const hasDTS = 0b0100_0000
+		if flags&hasDTS != 0 {
+			pkt.DTS = ParseTime(p.Payload[minHeaderSize+5:])
+		}
+	}
+
+	pkt.Payload = p.Payload[minHeaderSize+hSize:]
+
+	return pkt
+}
+
+func ParseTime(b []byte) time.Duration {
+	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)
+	return time.Duration(ts)
+}