mirror of
https://github.com/aler9/gortsplib
synced 2025-10-07 08:01:14 +08:00
89 lines
1.9 KiB
Go
89 lines
1.9 KiB
Go
package rtpmpeg4audio
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import (
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"crypto/rand"
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"github.com/pion/rtp"
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)
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const (
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rtpVersion = 2
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defaultPayloadMaxSize = 1460 // 1500 (UDP MTU) - 20 (IP header) - 8 (UDP header) - 12 (RTP header)
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)
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func randUint32() (uint32, error) {
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var b [4]byte
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_, err := rand.Read(b[:])
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if err != nil {
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return 0, err
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}
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return uint32(b[0])<<24 | uint32(b[1])<<16 | uint32(b[2])<<8 | uint32(b[3]), nil
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}
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// Encoder is a RTP/MPEG-4 audio encoder.
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// Specification: https://datatracker.ietf.org/doc/html/rfc3640
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// Specification: https://datatracker.ietf.org/doc/html/rfc6416#section-7.3
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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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// use RFC6416 (LATM) instead of RFC3640 (generic).
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LATM bool
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// The number of bits in which the AU-size field is encoded in the AU-header.
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SizeLength int
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// The number of bits in which the AU-Index is encoded in the first AU-header.
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IndexLength int
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// The number of bits in which the AU-Index-delta field is encoded in any non-first AU-header.
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IndexDeltaLength int
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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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// 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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}
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// Init initializes the encoder.
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func (e *Encoder) Init() error {
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if e.SSRC == nil {
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v, err := randUint32()
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if err != nil {
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return err
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}
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e.SSRC = &v
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}
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if e.InitialSequenceNumber == nil {
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v, err := randUint32()
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if err != nil {
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return err
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}
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v2 := uint16(v)
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e.InitialSequenceNumber = &v2
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}
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if e.PayloadMaxSize == 0 {
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e.PayloadMaxSize = defaultPayloadMaxSize
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}
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e.sequenceNumber = *e.InitialSequenceNumber
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return nil
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}
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// Encode encodes AUs into RTP packets.
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func (e *Encoder) Encode(aus [][]byte) ([]*rtp.Packet, error) {
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if !e.LATM {
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return e.encodeGeneric(aus)
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}
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return e.encodeLATM(aus)
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}
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