From 534cc01b857fa87c3b6628c79f37e64e07f77097 Mon Sep 17 00:00:00 2001
From: cnderrauber <zengjie9004@gmail.com>
Date: Wed, 23 Mar 2022 16:52:40 +0800
Subject: [PATCH] refine dynacast pause delay (#558)

* refine dynacast pause delay

* fix test
---
 pkg/config/config.go               | 4 ++--
 pkg/rtc/mediatrack_test.go         | 4 +++-
 pkg/rtc/mediatracksubscriptions.go | 9 ++++++---
 3 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/pkg/config/config.go b/pkg/config/config.go
index 1b13a1aec..b6ad89b9c 100644
--- a/pkg/config/config.go
+++ b/pkg/config/config.go
@@ -114,7 +114,7 @@ type AudioConfig struct {
 }
 
 type VideoConfig struct {
-	SubscribedQualityUpdateThrottle time.Duration `yaml:"subscribed_quality_update_throttle,omitempty"`
+	DynacastPauseDelay time.Duration `yaml:"dynacast_pause_delay,omitempty"`
 }
 
 type RedisConfig struct {
@@ -213,7 +213,7 @@ func NewConfig(confString string, c *cli.Context) (*Config, error) {
 			SmoothIntervals: 2,
 		},
 		Video: VideoConfig{
-			SubscribedQualityUpdateThrottle: 5 * time.Second,
+			DynacastPauseDelay: 5 * time.Second,
 		},
 		Redis: RedisConfig{},
 		Room: RoomConfig{
diff --git a/pkg/rtc/mediatrack_test.go b/pkg/rtc/mediatrack_test.go
index 3be331d16..b8b2fe733 100644
--- a/pkg/rtc/mediatrack_test.go
+++ b/pkg/rtc/mediatrack_test.go
@@ -175,7 +175,7 @@ func TestSubscribedMaxQuality(t *testing.T) {
 				},
 			},
 			VideoConfig: config.VideoConfig{
-				SubscribedQualityUpdateThrottle: 100 * time.Millisecond,
+				DynacastPauseDelay: 100 * time.Millisecond,
 			},
 		})
 
@@ -240,6 +240,7 @@ func TestSubscribedMaxQuality(t *testing.T) {
 
 		// muting "s1" also should disable all qualities
 		mt.notifySubscriberMaxQuality("s1", livekit.VideoQuality_OFF)
+		time.Sleep(110 * time.Millisecond)
 
 		expectedSubscribedQualities = []*livekit.SubscribedQuality{
 			{Quality: livekit.VideoQuality_LOW, Enabled: false},
@@ -251,6 +252,7 @@ func TestSubscribedMaxQuality(t *testing.T) {
 
 		// unmuting "s1" should enable previously set max quality
 		mt.notifySubscriberMaxQuality("s1", livekit.VideoQuality_LOW)
+		time.Sleep(110 * time.Millisecond)
 
 		expectedSubscribedQualities = []*livekit.SubscribedQuality{
 			{Quality: livekit.VideoQuality_LOW, Enabled: true},
diff --git a/pkg/rtc/mediatracksubscriptions.go b/pkg/rtc/mediatracksubscriptions.go
index a97563baf..67a009aca 100644
--- a/pkg/rtc/mediatracksubscriptions.go
+++ b/pkg/rtc/mediatracksubscriptions.go
@@ -65,7 +65,7 @@ func NewMediaTrackSubscriptions(params MediaTrackSubscriptionsParams) *MediaTrac
 		maxSubscriberQuality:         make(map[livekit.ParticipantID]livekit.VideoQuality),
 		maxSubscriberNodeQuality:     make(map[livekit.NodeID]livekit.VideoQuality),
 		maxSubscribedQuality:         livekit.VideoQuality_LOW,
-		maxSubscribedQualityDebounce: debounce.New(params.VideoConfig.SubscribedQualityUpdateThrottle),
+		maxSubscribedQualityDebounce: debounce.New(params.VideoConfig.DynacastPauseDelay),
 	}
 
 	return t
@@ -511,8 +511,11 @@ func (t *MediaTrackSubscriptions) UpdateQualityChange(force bool) {
 		return
 	}
 
-	if (t.maxSubscribedQuality != livekit.VideoQuality_OFF && maxSubscribedQuality != livekit.VideoQuality_OFF) &&
-		t.maxSubscribedQuality > maxSubscribedQuality && !force {
+	// if quality comes down(or become OFF), delay notify to publisher
+	if (t.maxSubscribedQuality != livekit.VideoQuality_OFF) &&
+		(t.maxSubscribedQuality > maxSubscribedQuality || maxSubscribedQuality == livekit.VideoQuality_OFF) &&
+		t.params.VideoConfig.DynacastPauseDelay > 0 && !force {
+
 		t.params.Logger.Debugw("throttle quality change", "from", t.maxSubscribedQuality, "to", maxSubscribedQuality)
 		t.maxQualityLock.Unlock()
 		t.maxSubscribedQualityDebounce(func() {