forked from livekit/server-sdk-go
/
nackgenerator.go
140 lines (117 loc) · 3.07 KB
/
nackgenerator.go
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package interceptor
import (
"sync"
"github.com/livekit/mediatransportutil/pkg/nack"
"github.com/pion/interceptor"
"github.com/pion/rtcp"
"go.uber.org/atomic"
)
type NackGeneratorInterceptorFactory struct {
lock sync.Mutex
interceptors []*NackGeneratorInterceptor
}
// NewInterceptor constructs a new ReceiverInterceptor
func (g *NackGeneratorInterceptorFactory) NewInterceptor(id string) (interceptor.Interceptor, error) {
i, err := NewNackGeneratorInterceptor()
if err != nil {
return nil, err
}
g.lock.Lock()
g.interceptors = append(g.interceptors, i)
g.lock.Unlock()
return i, err
}
func (g *NackGeneratorInterceptorFactory) SetRTT(rtt uint32) {
g.lock.Lock()
defer g.lock.Unlock()
for _, i := range g.interceptors {
i.SetRTT(rtt)
}
}
type NackGeneratorInterceptor struct {
interceptor.NoOp
lock sync.Mutex
writer atomic.Value
nackQueues map[uint32]*nack.NackQueue
}
func NewNackGeneratorInterceptor() (*NackGeneratorInterceptor, error) {
n := &NackGeneratorInterceptor{
nackQueues: make(map[uint32]*nack.NackQueue),
}
return n, nil
}
func (n *NackGeneratorInterceptor) SetRTT(rtt uint32) {
n.lock.Lock()
defer n.lock.Unlock()
for _, q := range n.nackQueues {
q.SetRTT(rtt)
}
}
func (n *NackGeneratorInterceptor) BindRTCPWriter(writer interceptor.RTCPWriter) interceptor.RTCPWriter {
n.writer.Store(writer)
return writer
}
func (n *NackGeneratorInterceptor) BindRemoteStream(info *interceptor.StreamInfo, reader interceptor.RTPReader) interceptor.RTPReader {
if !streamSupportNack(info) {
return reader
}
nackQueue := nack.NewNACKQueue()
n.lock.Lock()
n.nackQueues[info.SSRC] = nackQueue
n.lock.Unlock()
nackQueue.SetRTT(70)
var (
firstReceived bool
highestSeq uint16
)
ssrc := info.SSRC
return interceptor.RTPReaderFunc(func(b []byte, a interceptor.Attributes) (int, interceptor.Attributes, error) {
i, attr, err := reader.Read(b, a)
if err != nil {
return 0, nil, err
}
if attr == nil {
attr = make(interceptor.Attributes)
}
header, err := attr.GetRTPHeader(b[:i])
if err != nil {
return 0, nil, err
}
if !firstReceived {
firstReceived = true
highestSeq = header.SequenceNumber
} else {
nackQueue.Remove(header.SequenceNumber)
if diff := header.SequenceNumber - highestSeq; diff > 0 && diff < 0x8000 {
for seq := highestSeq + 1; seq < header.SequenceNumber; seq++ {
nackQueue.Push(seq)
}
highestSeq = header.SequenceNumber
}
}
if nacks, _ := nackQueue.Pairs(); len(nacks) > 0 {
pkts := []rtcp.Packet{&rtcp.TransportLayerNack{
SenderSSRC: ssrc,
MediaSSRC: ssrc,
Nacks: nacks,
}}
if w := n.writer.Load(); w != nil {
w.(interceptor.RTCPWriter).Write(pkts, nil)
}
}
return i, attr, nil
})
}
func (n *NackGeneratorInterceptor) UnbindRemoteStream(info *interceptor.StreamInfo) {
n.lock.Lock()
defer n.lock.Unlock()
delete(n.nackQueues, info.SSRC)
}
func streamSupportNack(info *interceptor.StreamInfo) bool {
for _, fb := range info.RTCPFeedback {
if fb.Type == "nack" && fb.Parameter == "" {
return true
}
}
return false
}