Join WAV files into a WMA file with NAudio - COMException fixed

JoiningWaveProvider.cs

class JoiningWaveProvider : IWaveProvider
{
    public JoiningWaveProvider(IEnumerable<MediaFoundationReader> inputFileReaders)
    {
        if (! inputFileReaders.Any())
        {
            throw new ArgumentException("At least one input file currentReader is needed");
        }

        WaveFormat firstFormat = inputFileReaders.First().WaveFormat;

        IEnumerable<MediaFoundationReader> nonMatchingReaders = 
            inputFileReaders.Where(reader => !reader.WaveFormat.Equals(firstFormat));

        if (nonMatchingReaders.Any())
        {
            throw new ArgumentException("All readers must have the same WAV format");
        }

        WaveFormat = firstFormat;

        _inputFileReaders = inputFileReaders.ToList();

        _readIndex = 0;
    }

    public WaveFormat WaveFormat { get; private set; }

    public int Read(byte[] buffer, int offset, int count)
    {
        int currentOffset = offset;
        int totalRead = 0;
        int remaining = count;

        for (int i = _readIndex; i < _inputFileReaders.Count && remaining > 0; i++, _readIndex++)
        {
            MediaFoundationReader currentReader = _inputFileReaders[i];

            int readNow = currentReader.Read(buffer, currentOffset, remaining);

            currentOffset += readNow;
            totalRead += readNow;
            remaining -= readNow;
        }

        return totalRead;
    }

    private int _readIndex;

    private readonly List<MediaFoundationReader> _inputFileReaders;
}

JoinWavFilesIntoWma.cs

// ...

/* Mixing WaveFileReader with MediaFoundationEncoder causes an exception. 
 * Stick with MediaFoundationReader when working with MediaFoundation namespace.
List<WaveFileReader> waveFileReaders = BuildTheReaderListFromPathNames();
*/
List<MediaFoundationReader> waveFileReaders = BuildTheReaderListFromPathNames();

IWaveProvider joinedWaveProvider = buildProvider(waveFileReaders);

// This one causes Exception
MediaFoundationEncoder.EncodeToWma(joinedWaveProvider, _joinedOutputFile, 48000);

// ...