Simplifying (hopefully) sfu.DownTrack (#213)

* Simplifying (hopefully) sfu.DownTrack

* Remove unnecessary check as pdding only packets are dropped before that check

* Temporal filtering max layer

* - Split out forwarder bits into a separate structure
- Address comments from Jie and David

* Remove debug and unneeded stuff

* Fix test

* Remove unneeded default initialization

pkg/rtc/participant.go

@@ -707,8 +707,7 @@ func (p *ParticipantImpl) GetConnectionQuality() livekit.ConnectionQuality {
 		if subTrack.IsMuted() {
 			continue
 		}
-		// LK-TODO: maybe this should check CurrentSpatialLayer as target may not have been achieved
-		if subTrack.DownTrack().TargetSpatialLayer() < subTrack.DownTrack().MaxSpatialLayer() {
+		if subTrack.DownTrack().GetForwardingStatus() != sfu.ForwardingStatusOptimal {
 			reducedQualitySub = true
 		}
 		subLoss += subTrack.SubscribeLossPercentage()

pkg/sfu/buffer/helpers.go

@@ -45,17 +45,14 @@ func (a *atomicBool) get() bool {
 			+-+-+-+-+-+-+-+-+
 */
 type VP8 struct {
-	TemporalSupported bool // LK-TODO: CLEANUP-REMOVE
-	FirstByte         byte
+	FirstByte byte
 
 	PictureIDPresent int
 	PictureID        uint16 /* 8 or 16 bits, picture ID */
-	PicIDIdx         int    // LK-TODO: CLEANUP-REMOVE
 	MBit             bool
 
 	TL0PICIDXPresent int
 	TL0PICIDX        uint8 /* 8 bits temporal level zero index */
-	TlzIdx           int   // LK-TODO: CLEANUP-REMOVE
 
 	// Optional Header If either of the T or K bits are set to 1,
 	// the TID/Y/KEYIDX extension field MUST be present.
@@ -100,15 +97,12 @@ func (p *VP8) Unmarshal(payload []byte) error {
 		if L && !T {
 			return errInvalidPacket
 		}
-		// Check if T is present, if not, no temporal layer is available
-		p.TemporalSupported = payload[idx]&0x20 > 0
 		// Check for PictureID
 		if I {
 			idx++
 			if payloadLen < idx+1 {
 				return errShortPacket
 			}
-			p.PicIDIdx = idx
 			p.PictureIDPresent = 1
 			pid := payload[idx] & 0x7f
 			// Check if m is 1, then Picture ID is 15 bits
@@ -129,7 +123,6 @@ func (p *VP8) Unmarshal(payload []byte) error {
 			if payloadLen < idx+1 {
 				return errShortPacket
 			}
-			p.TlzIdx = idx
 			p.TL0PICIDXPresent = 1
 
 			if int(idx) >= payloadLen {

pkg/sfu/buffer/helpers_test.go

@@ -75,7 +75,7 @@ func TestVP8Helper_Unmarshal(t *testing.T) {
 				t.Errorf("Unmarshal() error = %v, wantErr %v", err, tt.wantErr)
 			}
 			if tt.checkTemporal {
-				assert.Equal(t, tt.temporalSupport, p.TemporalSupported)
+				assert.Equal(t, tt.temporalSupport, p.TIDPresent == 1)
 			}
 			if tt.checkKeyFrame {
 				assert.Equal(t, tt.keyFrame, p.IsKeyFrame)

pkg/sfu/streamallocator.go

@@ -1225,11 +1225,13 @@ type Track struct {
 }
 
 func newTrack(downTrack *DownTrack, peerID string) *Track {
+	maxSpatialLayer, maxTemporalLayer := downTrack.MaxLayers()
+
 	return &Track{
 		downTrack:        downTrack,
 		peerID:           peerID,
-		maxSpatialLayer:  downTrack.MaxSpatialLayer(),
-		maxTemporalLayer: downTrack.MaxTemporalLayer(),
+		maxSpatialLayer:  maxSpatialLayer,
+		maxTemporalLayer: maxTemporalLayer,
 	}
 }