From a1338b149cf14e3496669528f42faba9a28b81ef Mon Sep 17 00:00:00 2001
From: Raja Subramanian <raja.gobi@tutanota.com>
Date: Wed, 8 Feb 2023 11:28:32 +0530
Subject: [PATCH] Limit layer to num advertised. (#1395)

* Limit layer to num advertised.

Otherwise, this leads to invalid layer for non-simulcast tracks.

* need to subtrack 1

* fix test
---
 pkg/sfu/forwarder.go      | 2 +-
 pkg/sfu/forwarder_test.go | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/pkg/sfu/forwarder.go b/pkg/sfu/forwarder.go
index 55b43a1f2..0cd185f65 100644
--- a/pkg/sfu/forwarder.go
+++ b/pkg/sfu/forwarder.go
@@ -746,7 +746,7 @@ func (f *Forwarder) AllocateOptimal(brs Bitrates, allowOvershoot bool) VideoAllo
 			} else {
 				// opportunisitically latch on to anything
 				alloc.targetLayers = VideoLayers{
-					Spatial:  DefaultMaxLayerSpatial,
+					Spatial:  int32(math.Max(0, float64(f.numAdvertisedLayers-1))),
 					Temporal: DefaultMaxLayerTemporal,
 				}
 			}
diff --git a/pkg/sfu/forwarder_test.go b/pkg/sfu/forwarder_test.go
index 5248bd587..d86371f51 100644
--- a/pkg/sfu/forwarder_test.go
+++ b/pkg/sfu/forwarder_test.go
@@ -197,10 +197,11 @@ func TestForwarderAllocateOptimal(t *testing.T) {
 	f.Mute(false)
 
 	// feed dry state, target set to maximum for opportunistic start
+	f.SetNumAdvertisedLayers(3)
 	f.lastAllocation.state = VideoAllocationStateNone
 	disable(f)
 	expectedTargetLayers := VideoLayers{
-		Spatial:  DefaultMaxLayerSpatial,
+		Spatial:  2,
 		Temporal: DefaultMaxLayerTemporal,
 	}
 	expectedResult = VideoAllocation{