use proper fix for using shared bufferFactory, remove resync hack

go.mod

@@ -34,4 +34,4 @@ require (
 	gopkg.in/yaml.v3 v3.0.0-20200615113413-eeeca48fe776
 )
 
-replace github.com/pion/ion-sfu => github.com/pion/ion-sfu v1.8.4-0.20210205220645-c9ec7ad1db86
+replace github.com/pion/ion-sfu => github.com/davidzhao/ion-sfu v1.8.3-0.20210208065837-f6e01b2d7aeb

go.sum

@@ -73,6 +73,8 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davidzhao/ion-sfu v1.8.3-0.20210205220645-c9ec7ad1db86 h1:POGjEQ8fyEQn96DMXMG7xhvWxHjNRMQ5aoiRzQOzOdY=
 github.com/davidzhao/ion-sfu v1.8.3-0.20210205220645-c9ec7ad1db86/go.mod h1:MKDh4JSLpBA/hFeYAYALb6nYpe6Ruknd3pmxPMbdpM8=
+github.com/davidzhao/ion-sfu v1.8.3-0.20210208065837-f6e01b2d7aeb h1:zrB9w2vGSzorwRYykHFMeMshWjMx/WU7J0T20Ta5WGo=
+github.com/davidzhao/ion-sfu v1.8.3-0.20210208065837-f6e01b2d7aeb/go.mod h1:MKDh4JSLpBA/hFeYAYALb6nYpe6Ruknd3pmxPMbdpM8=
 github.com/desertbit/timer v0.0.0-20180107155436-c41aec40b27f/go.mod h1:xH/i4TFMt8koVQZ6WFms69WAsDWr2XsYL3Hkl7jkoLE=
 github.com/dgrijalva/jwt-go v3.2.0+incompatible h1:7qlOGliEKZXTDg6OTjfoBKDXWrumCAMpl/TFQ4/5kLM=
 github.com/dgrijalva/jwt-go v3.2.0+incompatible/go.mod h1:E3ru+11k8xSBh+hMPgOLZmtrrCbhqsmaPHjLKYnJCaQ=

pkg/rtc/mediatrack.go

@@ -137,6 +137,7 @@ func (t *MediaTrack) AddSubscriber(sub types.Participant) error {
 	if err != nil {
 		return err
 	}
+	downTrack.SetBufferFactory(bufferFactory)
 	subTrack := NewSubscribedTrack(downTrack)
 
 	transceiver, err := sub.PeerConnection().AddTransceiverFromTrack(downTrack, webrtc.RTPTransceiverInit{

pkg/rtc/participant.go

@@ -580,8 +580,6 @@ func (p *ParticipantImpl) onMediaTrack(track *webrtc.TrackRemote, rtpReceiver *w
 	if newTrack {
 		p.handleTrackPublished(mt)
 	}
-
-	p.resyncSubscriptions()
 }
 
 func (p *ParticipantImpl) onDataChannel(dc *webrtc.DataChannel) {
@@ -646,7 +644,6 @@ func (p *ParticipantImpl) handleTrackPublished(track types.PublishedTrack) {
 			p.onTrackUpdated(p, track)
 		}
 		track.OnClose(nil)
-		go p.resyncSubscriptions()
 	})
 
 	if p.onTrackPublished != nil {
@@ -654,18 +651,6 @@ func (p *ParticipantImpl) handleTrackPublished(track types.PublishedTrack) {
 	}
 }
 
-func (p *ParticipantImpl) resyncSubscriptions() {
-	// TODO: video tracks the current participant is subscribed to tends to freeze when the participant adds/removes tracks
-	// to get around this, we'll trigger a resync on all tracks it's subscribed to
-	p.lock.RLock()
-	defer p.lock.RUnlock()
-	for _, tracks := range p.subscribedTracks {
-		for _, subTrack := range tracks {
-			subTrack.Resync()
-		}
-	}
-}
-
 // downTracksRTCPWorker sends SenderReports periodically when the participant is subscribed to
 // other publishedTracks in the room.
 func (p *ParticipantImpl) downTracksRTCPWorker() {

pkg/rtc/subscribedtrack.go

@@ -38,14 +38,6 @@ func (t *SubscribedTrack) SetPublisherMuted(muted bool) {
 	t.updateDownTrackMute()
 }
 
-// cause downtrack to resync and request a keyframe
-// this is sort of a hack to prevent a subscriber from having tracks freeze on the client due to missing
-// keyframes
-func (t *SubscribedTrack) Resync() {
-	t.dt.Mute(true)
-	t.updateDownTrackMute()
-}
-
 func (t *SubscribedTrack) updateDownTrackMute() {
 	muted := t.subMuted.Get() || t.pubMuted.Get()
 	t.dt.Mute(muted)

pkg/rtc/types/interfaces.go

@@ -109,7 +109,6 @@ type SubscribedTrack interface {
 	IsMuted() bool
 	SetMuted(muted bool)
 	SetPublisherMuted(muted bool)
-	Resync()
 }
 
 // interface for properties of webrtc.TrackRemote

pkg/rtc/types/typesfakes/fake_subscribed_track.go

@@ -29,10 +29,6 @@ type FakeSubscribedTrack struct {
 	isMutedReturnsOnCall map[int]struct {
 		result1 bool
 	}
-	ResyncStub        func()
-	resyncMutex       sync.RWMutex
-	resyncArgsForCall []struct {
-	}
 	SetMutedStub        func(bool)
 	setMutedMutex       sync.RWMutex
 	setMutedArgsForCall []struct {
@@ -153,30 +149,6 @@ func (fake *FakeSubscribedTrack) IsMutedReturnsOnCall(i int, result1 bool) {
 	}{result1}
 }
 
-func (fake *FakeSubscribedTrack) Resync() {
-	fake.resyncMutex.Lock()
-	fake.resyncArgsForCall = append(fake.resyncArgsForCall, struct {
-	}{})
-	stub := fake.ResyncStub
-	fake.recordInvocation("Resync", []interface{}{})
-	fake.resyncMutex.Unlock()
-	if stub != nil {
-		fake.ResyncStub()
-	}
-}
-
-func (fake *FakeSubscribedTrack) ResyncCallCount() int {
-	fake.resyncMutex.RLock()
-	defer fake.resyncMutex.RUnlock()
-	return len(fake.resyncArgsForCall)
-}
-
-func (fake *FakeSubscribedTrack) ResyncCalls(stub func()) {
-	fake.resyncMutex.Lock()
-	defer fake.resyncMutex.Unlock()
-	fake.ResyncStub = stub
-}
-
 func (fake *FakeSubscribedTrack) SetMuted(arg1 bool) {
 	fake.setMutedMutex.Lock()
 	fake.setMutedArgsForCall = append(fake.setMutedArgsForCall, struct {
@@ -248,8 +220,6 @@ func (fake *FakeSubscribedTrack) Invocations() map[string][][]interface{} {
 	defer fake.downTrackMutex.RUnlock()
 	fake.isMutedMutex.RLock()
 	defer fake.isMutedMutex.RUnlock()
-	fake.resyncMutex.RLock()
-	defer fake.resyncMutex.RUnlock()
 	fake.setMutedMutex.RLock()
 	defer fake.setMutedMutex.RUnlock()
 	fake.setPublisherMutedMutex.RLock()