move RTP decoders/encoders into pkt/rtpcodecs

2025-10-08 16:40:09 +08:00 · 2022-11-15 23:08:36 +01:00
parent 9795e9175a
commit c2c0230669
49 changed files with 14 additions and 15 deletions
--- a/pkg/rtpcodecs/rtplpcm/encoder.go
+++ b/pkg/rtpcodecs/rtplpcm/encoder.go
@@ -0,0 +1,123 @@
+package rtplpcm
+
+import (
+	"crypto/rand"
+	"fmt"
+	"time"
+
+	"github.com/pion/rtp"
+)
+
+const (
+	rtpVersion = 2
+)
+
+func randUint32() uint32 {
+	var b [4]byte
+	rand.Read(b[:])
+	return uint32(b[0])<<24 | uint32(b[1])<<16 | uint32(b[2])<<8 | uint32(b[3])
+}
+
+// Encoder is a RTP/LPCM encoder.
+type Encoder struct {
+	// payload type of packets.
+	PayloadType uint8
+
+	// SSRC of packets (optional).
+	// It defaults to a random value.
+	SSRC *uint32
+
+	// initial sequence number of packets (optional).
+	// It defaults to a random value.
+	InitialSequenceNumber *uint16
+
+	// initial timestamp of packets (optional).
+	// It defaults to a random value.
+	InitialTimestamp *uint32
+
+	// maximum size of packet payloads (optional).
+	// It defaults to 1460.
+	PayloadMaxSize int
+
+	BitDepth     int
+	SampleRate   int
+	ChannelCount int
+
+	sequenceNumber uint16
+	sampleSize     int
+	maxPayloadSize int
+}
+
+// Init initializes the encoder.
+func (e *Encoder) Init() {
+	if e.SSRC == nil {
+		v := randUint32()
+		e.SSRC = &v
+	}
+	if e.InitialSequenceNumber == nil {
+		v := uint16(randUint32())
+		e.InitialSequenceNumber = &v
+	}
+	if e.InitialTimestamp == nil {
+		v := randUint32()
+		e.InitialTimestamp = &v
+	}
+	if e.PayloadMaxSize == 0 {
+		e.PayloadMaxSize = 1460 // 1500 (UDP MTU) - 20 (IP header) - 8 (UDP header) - 12 (RTP header)
+	}
+
+	e.sequenceNumber = *e.InitialSequenceNumber
+	e.sampleSize = e.BitDepth * e.ChannelCount / 8
+	e.maxPayloadSize = (e.PayloadMaxSize / e.sampleSize) * e.sampleSize
+}
+
+func (e *Encoder) encodeTimestamp(ts time.Duration) uint32 {
+	return *e.InitialTimestamp + uint32(ts.Seconds()*float64(e.SampleRate))
+}
+
+// Encode encodes audio samples into RTP packets.
+func (e *Encoder) Encode(samples []byte, pts time.Duration) ([]*rtp.Packet, error) {
+	slen := len(samples)
+	if (slen % e.sampleSize) != 0 {
+		return nil, fmt.Errorf("invalid samples")
+	}
+
+	n := (slen / e.maxPayloadSize)
+	if (slen % e.maxPayloadSize) != 0 {
+		n++
+	}
+
+	ret := make([]*rtp.Packet, n)
+	i := 0
+	pos := 0
+	payloadSize := e.maxPayloadSize
+
+	for {
+		if payloadSize > len(samples[pos:]) {
+			payloadSize = len(samples[pos:])
+		}
+
+		ret[i] = &rtp.Packet{
+			Header: rtp.Header{
+				Version:        rtpVersion,
+				PayloadType:    e.PayloadType,
+				SequenceNumber: e.sequenceNumber,
+				Timestamp:      e.encodeTimestamp(pts),
+				SSRC:           *e.SSRC,
+				Marker:         false,
+			},
+			Payload: samples[pos : pos+payloadSize],
+		}
+
+		e.sequenceNumber++
+		i++
+		pos += payloadSize
+		pts += time.Duration(payloadSize/e.sampleSize) * time.Second / time.Duration(e.SampleRate)
+
+		if pos == slen {
+			break
+		}
+	}
+
+	return ret, nil
+}