Concrete class prototype

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

@@ -0,0 +1,67 @@
+using System;
+using System.IO;
+
+namespace Discord.Audio
+{
+    public class RTPWriteStream : Stream
+    {
+        private readonly AudioClient _audioClient;
+        private readonly byte[] _nonce, _secretKey;
+        private int _samplesPerFrame;
+        private uint _ssrc, _timestamp = 0;
+
+        protected readonly byte[] _buffer;
+
+        public override bool CanRead => false;
+        public override bool CanSeek => false;
+        public override bool CanWrite => true;
+
+        internal RTPWriteStream(AudioClient audioClient, byte[] secretKey, int samplesPerFrame, uint ssrc, int bufferSize = 4000)
+        {
+            _audioClient = audioClient;
+            _secretKey = secretKey;
+            _samplesPerFrame = samplesPerFrame;
+            _ssrc = ssrc;
+            _buffer = new byte[bufferSize];
+            _nonce = new byte[24];
+            _nonce[0] = 0x80;
+            _nonce[1] = 0x78;
+            _nonce[8] = (byte)(_ssrc >> 24);
+            _nonce[9] = (byte)(_ssrc >> 16);
+            _nonce[10] = (byte)(_ssrc >> 8);
+            _nonce[11] = (byte)(_ssrc >> 0);
+        }
+
+        public override void Write(byte[] buffer, int offset, int count)
+        {
+            unchecked
+            {
+                if (_nonce[3]++ == byte.MaxValue)
+                    _nonce[2]++;
+
+                _timestamp += (uint)_samplesPerFrame;
+                _nonce[4] = (byte)(_timestamp >> 24);
+                _nonce[5] = (byte)(_timestamp >> 16);
+                _nonce[6] = (byte)(_timestamp >> 8);
+                _nonce[7] = (byte)(_timestamp >> 0);
+            }
+
+            count = SecretBox.Encrypt(buffer, offset, count, _buffer, 12, _nonce, _secretKey);
+            Buffer.BlockCopy(_nonce, 0, _buffer, 0, 12); //Copy the RTP header from nonce to buffer
+            _audioClient.Send(_buffer, count + 12);
+        }
+
+        public override void Flush() { }
+
+        public override long Length { get { throw new NotSupportedException(); } }
+        public override long Position
+        {
+            get { throw new NotSupportedException(); }
+            set { throw new NotSupportedException(); }
+        }
+
+        public override int Read(byte[] buffer, int offset, int count) { throw new NotSupportedException(); }
+        public override void SetLength(long value) { throw new NotSupportedException(); }
+        public override long Seek(long offset, SeekOrigin origin) { throw new NotSupportedException(); }
+    }
+}