Occasional System.IndexOutOfRangeException using Naudio WaveFileWriter - naudio

Question

I'm struggling with the below exception using WaveFileWriter. This exception occurs intermittently -- most times this works fine. Code snippet below:
MemoryStream s = new MemoryStream();
MemoryStream newStream = new MemoryStream();
int length = 0;
byte[] buffer = null;
int read = 0;
MixingSampleProvider mixer2 = new MixingSampleProvider(_samples);
SampleToWaveProvider16 mixer3 = new SampleToWaveProvider16(mixer2);
length = mixer3.WaveFormat.AverageBytesPerSecond*Convert.ToInt32(position.TotalSeconds); //position is a Timespan calculated to be the total duration of the WAV files
buffer = new byte[length];
WaveFileWriter waveFileWriter = new WaveFileWriter(new IgnoreDisposeStream(s), mixer3.WaveFormat);
while ((read = mixer3.Read(buffer, 0, buffer.Length)) > 0)
{
waveFileWriter.Write(buffer, 0, read);
}
waveFileWriter.Flush();
waveFileWriter.Close();
waveFileWriter.Dispose();
s.WriteTo(newStream);
Here are the details of the Exception:
System.IndexOutOfRangeException was caught
HResult=-2146233080
Message=Index was outside the bounds of the array.
Source=NAudio
StackTrace:
at NAudio.Wave.SampleProviders.Pcm16BitToSampleProvider.Read(Single[] buffer, Int32 offset, Int32 count)
at NAudio.Wave.SampleProviders.OffsetSampleProvider.Read(Single[] buffer, Int32 offset, Int32 count)
at NAudio.Wave.SampleProviders.MixingSampleProvider.Read(Single[] buffer, Int32 offset, Int32 count)
at NAudio.Wave.SampleProviders.OffsetSampleProvider.Read(Single[] buffer, Int32 offset, Int32 count)
at NAudio.Wave.SampleProviders.MixingSampleProvider.Read(Single[] buffer, Int32 offset, Int32 count)
at NAudio.Wave.SampleProviders.SampleToWaveProvider16.Read(Byte[] destBuffer, Int32 offset, Int32 numBytes)
at GamedayRadio.HalfInning.Process() in xxxxxx
InnerException:

Answer 1

Not sure if this is causing your error, but do make sure that the read length is an exact multiple of the BlockAlign for your WaveFormat. So for example when reading stereo 16 bit audio, always read multiples of 4 bytes (2 channels x 2 bytes per sample). Your buffer looks like it might be an odd number of bytes in some circumstances