snapshot of https://github.com/livekit/livekit.git @ 08c5433449c106943231037d0b892895f6e92d3b (2026-09-15)

pkg/sfu/bwe/bwe.go

@@ -0,0 +1,123 @@
+// Copyright 2023 LiveKit, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package bwe
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/livekit/livekit-server/pkg/sfu/ccutils"
+	"github.com/pion/rtcp"
+)
+
+// ------------------------------------------------
+
+const (
+	DefaultRTT         = float64(0.070) // 70 ms
+	RTTSmoothingFactor = float64(0.5)
+)
+
+// ------------------------------------------------
+
+type BWEType int
+
+const (
+	BWETypeNone BWEType = iota
+	BWETypeRemote
+	BWETypeSendSide
+)
+
+func (b BWEType) String() string {
+	switch b {
+	case BWETypeNone:
+		return "NONE"
+	case BWETypeRemote:
+		return "REMOTE"
+	case BWETypeSendSide:
+		return "SEND_SIDE"
+	default:
+		return fmt.Sprintf("%d", int(b))
+	}
+}
+
+// ------------------------------------------------
+
+type CongestionState int
+
+const (
+	CongestionStateNone CongestionState = iota
+	CongestionStateEarlyWarning
+	CongestionStateCongested
+)
+
+func (c CongestionState) String() string {
+	switch c {
+	case CongestionStateNone:
+		return "NONE"
+	case CongestionStateEarlyWarning:
+		return "EARLY_WARNING"
+	case CongestionStateCongested:
+		return "CONGESTED"
+	default:
+		return fmt.Sprintf("%d", int(c))
+	}
+}
+
+// ------------------------------------------------
+
+type BWE interface {
+	Type() BWEType
+
+	SetBWEListener(bweListner BWEListener)
+
+	Reset()
+
+	HandleREMB(
+		receivedEstimate int64,
+		expectedBandwidthUsage int64,
+		sentPackets uint32,
+		repeatedNacks uint32,
+	)
+
+	// TWCC sequence number
+	RecordPacketSendAndGetSequenceNumber(
+		atMicro int64,
+		size int,
+		isRTX bool,
+		probeClusterId ccutils.ProbeClusterId,
+		isProbe bool,
+	) uint16
+
+	HandleTWCCFeedback(report *rtcp.TransportLayerCC)
+
+	UpdateRTT(rtt float64)
+
+	CongestionState() CongestionState
+
+	CanProbe() bool
+	ProbeDuration() time.Duration
+	ProbeClusterStarting(pci ccutils.ProbeClusterInfo)
+	ProbeClusterDone(pci ccutils.ProbeClusterInfo)
+	ProbeClusterIsGoalReached() bool
+	ProbeClusterFinalize() (ccutils.ProbeSignal, int64, bool)
+}
+
+// ------------------------------------------------
+
+type BWEListener interface {
+	OnCongestionStateChange(fromState CongestionState, toState CongestionState, estimatedAvailableChannelCapacity int64)
+}
+
+// ------------------------------------------------