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

pkg/sfu/videolayerselector/decodetarget.go

@@ -0,0 +1,70 @@
+// 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 videolayerselector
+
+import (
+	"fmt"
+
+	"github.com/livekit/livekit-server/pkg/sfu/buffer"
+	dd "github.com/livekit/livekit-server/pkg/sfu/rtpextension/dependencydescriptor"
+)
+
+type DecodeTarget struct {
+	buffer.DependencyDescriptorDecodeTarget
+	chain  *FrameChain
+	active bool
+}
+
+type FrameDetectionResult struct {
+	TargetValid bool
+	DTI         dd.DecodeTargetIndication
+}
+
+func NewDecodeTarget(target buffer.DependencyDescriptorDecodeTarget, chain *FrameChain) *DecodeTarget {
+	return &DecodeTarget{
+		DependencyDescriptorDecodeTarget: target,
+		chain:                            chain,
+	}
+}
+
+func (dt *DecodeTarget) Valid() bool {
+	return dt.chain == nil || !dt.chain.Broken()
+}
+
+func (dt *DecodeTarget) Active() bool {
+	return dt.active
+}
+
+func (dt *DecodeTarget) UpdateActive(activeBitmask uint32) {
+	active := (activeBitmask & (1 << dt.Target)) != 0
+	dt.active = active
+	if dt.chain != nil {
+		dt.chain.UpdateActive(active)
+	}
+}
+
+func (dt *DecodeTarget) OnFrame(extFrameNum uint64, fd *dd.FrameDependencyTemplate) (FrameDetectionResult, error) {
+	result := FrameDetectionResult{}
+	if len(fd.DecodeTargetIndications) <= dt.Target {
+		return result, fmt.Errorf("mismatch target %d and len(DecodeTargetIndications) %d", dt.Target, len(fd.DecodeTargetIndications))
+	}
+
+	result.DTI = fd.DecodeTargetIndications[dt.Target]
+	// The encoder can choose not to use frame chain in theory, and we need to trace every required frame is decodable in this case.
+	// But we don't observe this in browser and it makes no sense to not use the chain with svc, so only use chain to detect decode target broken now,
+	// and always return decodable if it is not protect by chain.
+	result.TargetValid = dt.Valid()
+	return result, nil
+}