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server/vendor/github.com/pion/rtp/packetizer.go

@@ -0,0 +1,138 @@
+// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+package rtp
+
+import (
+	"time"
+)
+
+// Payloader payloads a byte array for use as rtp.Packet payloads
+type Payloader interface {
+	Payload(mtu uint16, payload []byte) [][]byte
+}
+
+// Packetizer packetizes a payload
+type Packetizer interface {
+	Packetize(payload []byte, samples uint32) []*Packet
+	GeneratePadding(samples uint32) []*Packet
+	EnableAbsSendTime(value int)
+	SkipSamples(skippedSamples uint32)
+}
+
+type packetizer struct {
+	MTU         uint16
+	PayloadType uint8
+	SSRC        uint32
+	Payloader   Payloader
+	Sequencer   Sequencer
+	Timestamp   uint32
+
+	// Deprecated: will be removed in a future version.
+	ClockRate uint32
+
+	extensionNumbers struct { // put extension numbers in here. If they're 0, the extension is disabled (0 is not a legal extension number)
+		AbsSendTime int // http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time
+	}
+	timegen func() time.Time
+}
+
+// NewPacketizer returns a new instance of a Packetizer for a specific payloader
+func NewPacketizer(mtu uint16, pt uint8, ssrc uint32, payloader Payloader, sequencer Sequencer, clockRate uint32) Packetizer {
+	return &packetizer{
+		MTU:         mtu,
+		PayloadType: pt,
+		SSRC:        ssrc,
+		Payloader:   payloader,
+		Sequencer:   sequencer,
+		Timestamp:   globalMathRandomGenerator.Uint32(),
+		ClockRate:   clockRate,
+		timegen:     time.Now,
+	}
+}
+
+func (p *packetizer) EnableAbsSendTime(value int) {
+	p.extensionNumbers.AbsSendTime = value
+}
+
+// Packetize packetizes the payload of an RTP packet and returns one or more RTP packets
+func (p *packetizer) Packetize(payload []byte, samples uint32) []*Packet {
+	// Guard against an empty payload
+	if len(payload) == 0 {
+		return nil
+	}
+
+	payloads := p.Payloader.Payload(p.MTU-12, payload)
+	packets := make([]*Packet, len(payloads))
+
+	for i, pp := range payloads {
+		packets[i] = &Packet{
+			Header: Header{
+				Version:        2,
+				Padding:        false,
+				Extension:      false,
+				Marker:         i == len(payloads)-1,
+				PayloadType:    p.PayloadType,
+				SequenceNumber: p.Sequencer.NextSequenceNumber(),
+				Timestamp:      p.Timestamp, // Figure out how to do timestamps
+				SSRC:           p.SSRC,
+				CSRC:           []uint32{},
+			},
+			Payload: pp,
+		}
+	}
+	p.Timestamp += samples
+
+	if len(packets) != 0 && p.extensionNumbers.AbsSendTime != 0 {
+		sendTime := NewAbsSendTimeExtension(p.timegen())
+		// apply http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time
+		b, err := sendTime.Marshal()
+		if err != nil {
+			return nil // never happens
+		}
+		err = packets[len(packets)-1].SetExtension(uint8(p.extensionNumbers.AbsSendTime), b)
+		if err != nil {
+			return nil // never happens
+		}
+	}
+
+	return packets
+}
+
+// GeneratePadding returns required padding-only packages
+func (p *packetizer) GeneratePadding(samples uint32) []*Packet {
+	// Guard against an empty payload
+	if samples == 0 {
+		return nil
+	}
+
+	packets := make([]*Packet, samples)
+
+	for i := 0; i < int(samples); i++ {
+		pp := make([]byte, 255)
+		pp[254] = 255
+
+		packets[i] = &Packet{
+			Header: Header{
+				Version:        2,
+				Padding:        true,
+				Extension:      false,
+				Marker:         false,
+				PayloadType:    p.PayloadType,
+				SequenceNumber: p.Sequencer.NextSequenceNumber(),
+				Timestamp:      p.Timestamp, // Use latest timestamp
+				SSRC:           p.SSRC,
+				CSRC:           []uint32{},
+			},
+			Payload: pp,
+		}
+	}
+
+	return packets
+}
+
+// SkipSamples causes a gap in sample count between Packetize requests so the
+// RTP payloads produced have a gap in timestamps
+func (p *packetizer) SkipSamples(skippedSamples uint32) {
+	p.Timestamp += skippedSamples
+}