mirror of
https://github.com/aler9/gortsplib
synced 2025-10-05 07:06:58 +08:00
100 lines
2.1 KiB
Go
100 lines
2.1 KiB
Go
package rtpvp8
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import (
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"crypto/rand"
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"fmt"
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"time"
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"github.com/pion/rtp"
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"github.com/pion/rtp/codecs"
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"github.com/bluenviron/gortsplib/v3/pkg/rtptime"
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)
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const (
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rtpVersion = 2
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)
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func randUint32() uint32 {
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var b [4]byte
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rand.Read(b[:])
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return uint32(b[0])<<24 | uint32(b[1])<<16 | uint32(b[2])<<8 | uint32(b[3])
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}
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// Encoder is a RTP/VP8 encoder.
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type Encoder struct {
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// payload type of packets.
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PayloadType uint8
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// SSRC of packets (optional).
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// It defaults to a random value.
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SSRC *uint32
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// initial sequence number of packets (optional).
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// It defaults to a random value.
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InitialSequenceNumber *uint16
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// initial timestamp of packets (optional).
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// It defaults to a random value.
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InitialTimestamp *uint32
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// maximum size of packet payloads (optional).
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// It defaults to 1460.
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PayloadMaxSize int
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sequenceNumber uint16
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timeEncoder *rtptime.Encoder
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vp codecs.VP8Payloader
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}
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// Init initializes the encoder.
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func (e *Encoder) Init() {
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if e.SSRC == nil {
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v := randUint32()
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e.SSRC = &v
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}
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if e.InitialSequenceNumber == nil {
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v := uint16(randUint32())
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e.InitialSequenceNumber = &v
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}
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if e.InitialTimestamp == nil {
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v := randUint32()
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e.InitialTimestamp = &v
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}
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if e.PayloadMaxSize == 0 {
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e.PayloadMaxSize = 1460 // 1500 (UDP MTU) - 20 (IP header) - 8 (UDP header) - 12 (RTP header)
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}
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e.sequenceNumber = *e.InitialSequenceNumber
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e.timeEncoder = rtptime.NewEncoder(rtpClockRate, *e.InitialTimestamp)
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}
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// Encode encodes a VP8 frame into RTP/VP8 packets.
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func (e *Encoder) Encode(frame []byte, pts time.Duration) ([]*rtp.Packet, error) {
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payloads := e.vp.Payload(uint16(e.PayloadMaxSize), frame)
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if payloads == nil {
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return nil, fmt.Errorf("payloader failed")
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}
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plen := len(payloads)
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ret := make([]*rtp.Packet, plen)
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for i, payload := range payloads {
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ret[i] = &rtp.Packet{
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Header: rtp.Header{
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Version: rtpVersion,
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PayloadType: e.PayloadType,
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SequenceNumber: e.sequenceNumber,
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Timestamp: e.timeEncoder.Encode(pts),
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SSRC: *e.SSRC,
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Marker: i == (plen - 1),
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},
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Payload: payload,
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}
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e.sequenceNumber++
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}
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return ret, nil
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}
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