Transceiver leak (only for video tracks) (#775)

Resolves #420 

This time restricting to video tracks (where it really matters), due to
reproducible crashes in the audio stack.

Author: pblazej

.changes/transceiver-refix

@@ -0,0 +1 @@
+patch type="fixed" "Restrict transceiver memory leak fix to video tracks"

Package.swift

@@ -19,7 +19,7 @@ let package = Package(
     ],
     dependencies: [
         // LK-Prefixed Dynamic WebRTC XCFramework
-        .package(url: "https://github.com/livekit/webrtc-xcframework.git", exact: "137.7151.04"),
+        .package(url: "https://github.com/livekit/webrtc-xcframework.git", exact: "137.7151.05"),
         .package(url: "https://github.com/apple/swift-protobuf.git", from: "1.29.0"),
         .package(url: "https://github.com/apple/swift-log.git", from: "1.6.2"),
         .package(url: "https://github.com/apple/swift-collections.git", from: "1.1.0"),

Package@swift-6.0.swift

@@ -20,7 +20,7 @@ let package = Package(
     ],
     dependencies: [
         // LK-Prefixed Dynamic WebRTC XCFramework
-        .package(url: "https://github.com/livekit/webrtc-xcframework.git", exact: "137.7151.04"),
+        .package(url: "https://github.com/livekit/webrtc-xcframework.git", exact: "137.7151.05"),
         .package(url: "https://github.com/apple/swift-protobuf.git", from: "1.29.0"),
         .package(url: "https://github.com/apple/swift-log.git", from: "1.6.2"),
         .package(url: "https://github.com/apple/swift-collections.git", from: "1.1.0"),

Sources/LiveKit/Core/Transport.swift

@@ -326,6 +326,19 @@ extension Transport {
         guard _pc.removeTrack(sender) else {
             throw LiveKitError(.webRTC, message: "Failed to remove track")
         }
+
+        releaseTransceiver(sender: sender)
+    }
+
+    // Try to stop the transceiver and free the resources
+    // Workaround: https://groups.google.com/g/discuss-webrtc/c/WDsGuVucBjQ?pli=1
+    private func releaseTransceiver(sender: LKRTCRtpSender) {
+        if let transceiver = _pc.transceivers.first(where: { $0.sender == sender }),
+           transceiver.mediaType == .video, !transceiver.isStopped
+        {
+            log("Stopping video transceiver", .debug)
+            transceiver.stopInternal()
+        }
     }
 
     func dataChannel(for label: String,