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

pkg/sfu/videolayerselector/framenumberwrapper_test.go

@@ -0,0 +1,108 @@
+// Copyright 2024 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 (
+	"testing"
+
+	"math/rand"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/livekit/mediatransportutil/pkg/utils"
+	"github.com/livekit/protocol/logger"
+)
+
+func TestFrameNumberWrapper(t *testing.T) {
+
+	logger.InitFromConfig(&logger.Config{Level: "debug"}, t.Name())
+
+	fnWrap := &FrameNumberWrapper{logger: logger.GetLogger()}
+
+	fnWrapAround := utils.NewWrapAround[uint16, uint64](utils.WrapAroundParams{IsRestartAllowed: false})
+
+	firstF := uint16(1000)
+
+	testFrameOrder := func(frame uint16, isKeyFrame bool, frame2 uint16, isKeyFrame2, expectInorder bool) {
+		frameUnwrap := fnWrapAround.Update(frame).ExtendedVal
+		wrappedFrame := uint16(fnWrap.UpdateAndGet(frameUnwrap, isKeyFrame))
+
+		// make sure wrap around always get in order frame number
+		fnWrapAround.Update(frame + (frame2-frame)/2)
+
+		frame2Unwrap := fnWrapAround.Update(frame2).ExtendedVal
+		wrappedFrame2 := uint16(fnWrap.UpdateAndGet(frame2Unwrap, isKeyFrame2))
+		// keeps order
+		require.Equal(t, expectInorder, inOrder(wrappedFrame2, wrappedFrame), "frame %d, frame2 %d, wrappedFrame %d, wrapped Frame2 %d, frameUnwrap %d, frame2Unwrap %d", frame, frame2, wrappedFrame, wrappedFrame2, frameUnwrap, frame2Unwrap)
+		// frame number diff should be the same if frame2 is not a key frame
+		if !isKeyFrame2 {
+			require.Equal(t, frame2-frame, wrappedFrame2-wrappedFrame)
+		}
+	}
+
+	secondF := getFrame(firstF, true)
+	testFrameOrder(firstF, true, secondF, false, true)
+
+	// non key frame keeps diff and order
+	for i := 0; i < 100; i++ {
+		// frame in order
+		firstF = secondF
+		secondF = getFrame(firstF, true)
+		testFrameOrder(firstF, false, secondF, false, true)
+
+		// frame out of order
+		firstF = secondF
+		secondF = getFrame(firstF, false)
+		// it is possible that an out of order non-keyframe has been converted to in order frame number if the diff is 32768
+		// that is ok because the client can't decode in such case and always need to wait for the key frame.
+		// so it is just a failure of test case and increase the frame number here.
+		if secondF-firstF == 0x8000 {
+			secondF++
+		}
+		testFrameOrder(firstF, false, secondF, false, false)
+
+		// key frame in order
+		firstF = secondF
+		secondF = getFrame(firstF, true)
+		testFrameOrder(firstF, false, secondF, true, true)
+
+		// frame in order
+		firstF = secondF
+		secondF = getFrame(firstF, true)
+		testFrameOrder(firstF, false, secondF, false, true)
+
+		// key frame out of order but should be in order after wrap around
+		firstF = secondF
+		secondF = getFrame(firstF, false)
+		testFrameOrder(firstF, false, secondF, true, true)
+	}
+}
+
+func inOrder(a, b uint16) bool {
+	return a-b < 0x8000 || (a-b == 0x8000 && a > b)
+}
+
+func getFrame(base uint16, inorder bool) uint16 {
+	if inorder {
+		return base + uint16(rand.Intn(0x8000))
+	}
+
+	for {
+		ret := base + uint16(rand.Intn(0x8000)) + 0x8000
+		if !inOrder(ret, base) {
+			return ret
+		}
+	}
+}