InputStream reads should wait until data is available.

src/Discord.Net.Core/Audio/AudioInStream.cs

@@ -11,9 +11,9 @@ namespace Discord.Audio
         public override bool CanSeek => false;
         public override bool CanWrite => true;
 
-        public abstract Task<RTPFrame?> ReadFrameAsync(CancellationToken cancelToken);
+        public abstract Task<RTPFrame> ReadFrameAsync(CancellationToken cancelToken);
 
-        public RTPFrame? ReadFrame()
+        public RTPFrame ReadFrame()
         {
             return ReadFrameAsync(CancellationToken.None).GetAwaiter().GetResult();
         }

src/Discord.Net.Core/Audio/IAudioClient.cs

@@ -10,6 +10,7 @@ namespace Discord.Audio
         event Func<int, int, Task> LatencyUpdated;
         event Func<ulong, AudioInStream, Task> StreamCreated;
         event Func<ulong, Task> StreamDestroyed;
+        event Func<ulong, bool, Task> SpeakingUpdated;
 
         /// <summary> Gets the current connection state of this client. </summary>
         ConnectionState ConnectionState { get; }

src/Discord.Net.WebSocket/Audio/Streams/InputStream.cs

@@ -8,7 +8,10 @@ namespace Discord.Audio.Streams
     ///<summary> Reads the payload from an RTP frame </summary>
     public class InputStream : AudioInStream
     {
+        private const int MaxFrames = 100;
+
         private ConcurrentQueue<RTPFrame> _frames;
+        private SemaphoreSlim _signal;
         private ushort _nextSeq;
         private uint _nextTimestamp;
         private bool _hasHeader;
@@ -21,28 +24,27 @@ namespace Discord.Audio.Streams
         public InputStream()
         {
             _frames = new ConcurrentQueue<RTPFrame>();
+            _signal = new SemaphoreSlim(0, MaxFrames);
         }
 
-        public override Task<RTPFrame?> ReadFrameAsync(CancellationToken cancelToken)
+        public override async Task<RTPFrame> ReadFrameAsync(CancellationToken cancelToken)
         {
             cancelToken.ThrowIfCancellationRequested();
 
-            if (_frames.TryDequeue(out var frame))
-                return Task.FromResult<RTPFrame?>(frame);
-            return Task.FromResult<RTPFrame?>(null);
+            RTPFrame frame;
+            await _signal.WaitAsync(cancelToken).ConfigureAwait(false);
+            _frames.TryDequeue(out frame);
+            return frame;
         }
-        public override Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancelToken)
+        public override async Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancelToken)
         {
             cancelToken.ThrowIfCancellationRequested();
-            
-            if (_frames.TryDequeue(out var frame))
-            {
-                if (count < frame.Payload.Length)
-                    throw new InvalidOperationException("Buffer is too small.");
-                Buffer.BlockCopy(frame.Payload, 0, buffer, offset, frame.Payload.Length);
-                return Task.FromResult(frame.Payload.Length);
-            }
-            return Task.FromResult(0);
+
+            var frame = await ReadFrameAsync(cancelToken).ConfigureAwait(false);
+            if (count < frame.Payload.Length)
+                throw new InvalidOperationException("Buffer is too small.");
+            Buffer.BlockCopy(frame.Payload, 0, buffer, offset, frame.Payload.Length);
+            return frame.Payload.Length;
         }
 
         public void WriteHeader(ushort seq, uint timestamp)
@@ -57,7 +59,7 @@ namespace Discord.Audio.Streams
         {
             cancelToken.ThrowIfCancellationRequested();
 
-            if (_frames.Count > 100) //1-2 seconds
+            if (_frames.Count > MaxFrames) //1-2 seconds
             {
                 _hasHeader = false;
                 return Task.Delay(0); //Buffer overloaded
@@ -72,6 +74,7 @@ namespace Discord.Audio.Streams
                 timestamp: _nextTimestamp,
                 payload: payload
             ));
+            _signal.Release();
             _hasHeader = false;
             return Task.Delay(0);
         }