feat: AudioStream | expose frame-activity oracle (LastFrameReceivedAt)

Runtime/Scripts/Rooms/Streaming/Audio/AudioStream.cs

@@ -28,6 +28,8 @@ public class AudioStream : IDisposable
 
         public WavTeeControl WavTeeControl => currentInternal.WavTeeControl;
 
+        public int LastFrameReceivedAt => currentInternal.LastFrameReceivedAt;
+
         public AudioStream(StreamKey streamKey, LiveKit.Rooms.Tracks.ITrack track)
         {
             this.streamKey = streamKey;
@@ -106,11 +108,14 @@ public class AudioStreamInternal : IDisposable
             );
 
         private bool disposed;
+        private int lastFrameReceivedAt = -1;
 
         public readonly AudioStreamInfo audioStreamInfo;
         private readonly uint internalChannels;
         private readonly uint internalSampleRate;
 
+        public int LastFrameReceivedAt => Volatile.Read(ref lastFrameReceivedAt);
+
         public WavTeeControl WavTeeControl
         {
             get
@@ -222,6 +227,8 @@ private void OnAudioStreamEvent(AudioStreamEvent e)
                 return;
             }
 
+            Volatile.Write(ref lastFrameReceivedAt, Environment.TickCount);
+
             using var guard = buffer.Lock();
             guard.Value.Write(frame);
             guard.Value.TryWriteWavTee(frame, frame);

Runtime/Scripts/Rooms/Streaming/Audio/AudioStreams.cs

@@ -22,6 +22,12 @@ protected override AudioStreamInfo InfoFromStream(AudioStream stream)
         {
             return stream.AudioStreamInfo;
         }
+
+        public int GetLastFrameReceivedAt(StreamKey streamKey)
+        {
+            var weak = ActiveStream(streamKey);
+            return weak.Resource.Has ? weak.Resource.Value.LastFrameReceivedAt : -1;
+        }
     }
 }
 

Runtime/Scripts/Rooms/Streaming/Audio/IAudioStreams.cs

@@ -4,7 +4,7 @@ namespace LiveKit.Rooms.Streaming.Audio
 {
     public interface IAudioStreams : IStreams<AudioStream, AudioStreamInfo>
     {
-
+        int GetLastFrameReceivedAt(StreamKey streamKey);
     }
 }