Help Locate the bug code of "rtl_tcp + sdr# = buzzing"

[yu]

First a picture of the bug .

If using rtl_tcp with sdr# in raspberry Pi or other embedded machines, something described in Rtl_tcp issues or raspberry_pi_rtl_tcp_problems may happen, no hints to solve this bug until this thread appear for_those_having_problem_with_rtl_tcp.

I decompile the sdrsharper's SDRSharp.RTLTCP.dll, and found that the dll is using an old codebase of sdrsharp . 

I minimize the bug area of the code in RTLTCPIO.cs, and list them below. After I replace the bug code with the right one, the bug did vanish, but I can't find why. which line of code on earth cause the buzzing?

bug code

    private void RecieveSamples()
    {
        var recBuffer = new byte[_bufferSize];
        var recUnsafeBuffer = UnsafeBuffer.Create(recBuffer);
        var recPtr = (byte*) recUnsafeBuffer;
        _iqBuffer = UnsafeBuffer.Create(_bufferSize / 2, sizeof(Complex));
        _iqBufferPtr = (Complex*) _iqBuffer;
        var offs = 0;                        
        while (_s != null && _s.Connected)
        {
            try
            {
                var bytesRec = _s.Receive(recBuffer, offs, _bufferSize - offs, SocketFlags.None);
                var totalBytes = offs + bytesRec;
                offs = totalBytes % 2; //Need to correctly handle the hypothetical case where we somehow get an odd number of bytes
                ProcessSamples(recPtr, totalBytes - offs); //This might work.
                if (offs == 1)
                {
                    recPtr[0] = recPtr[totalBytes - 1];
                }
            }
            catch
            {
                Close();
                break;
            }
        }            
    }

    private void ProcessSamples(byte* rawPtr, int len)
    {
        var sampleCount = len / 2;

        var ptr = _iqBufferPtr;
        for (var i = 0; i < sampleCount; i++)
        {
            ptr->Imag = _lutPtr[*rawPtr++];
            ptr->Real = _lutPtr[*rawPtr++];
            ptr++;
        }
        if (_callback != null)
        {
            _callback(this, _iqBufferPtr, sampleCount);
        }
    }

no bug code

        private UnsafeBuffer _b;

        private void RecieveSamples()
        {
            byte[] recBuffer = new byte[_bufferSize + 1024];
            int offs = 0;
            while (_callback != null && _s != null && _s.Connected)
            {
                try
                {
                    int bytesRec = _s.Receive(recBuffer, offs, _bufferSize, SocketFlags.None);
                    int totalBytes = offs + bytesRec;
                    offs = totalBytes % 2; //Need to correctly handle the hypothetical case where we somehow get an odd number of bytes
                    beamUpThemSamples(recBuffer, totalBytes - offs); //This might work.
                }
                catch (Exception e)
                {
                    Close();
                    break;
                }
            }
        }

        private void beamUpThemSamples(byte[] buffer, int len)
        {
            var sampleCount = len / 2;
            Complex* bufPtr;
            if (_b == null || _b.Length < sampleCount)
            {
                _b = UnsafeBuffer.Create(sampleCount, sizeof(Complex));
            }
            bufPtr = (Complex*)_b;

            for (int i = 0; i < sampleCount; i++)
            {
                bufPtr[i].Real = (buffer[i * 2 + 1] - 127.5f) / 127.5f;
                bufPtr[i].Imag = (buffer[i * 2] - 127.5f) / 127.5f ;
            }

            lock (this)
            {
                if (null == _callback) { return; }
                _callback(this, bufPtr, sampleCount);
            }
        }

p.s. the bug has nothing to do with the lock(this) code, I have confirmed that.

[yu]

ooops,  I forget the link of  "for_those_having_problem_with_rtl_tcp"

https://www.reddit.com/r/RTLSDR/comments/2y885a/for_those_having_problem_with_rtl_tcp/