Why is NAudio creating a WAV file that's twice the size it should be?

Question

I'm using this fairly standard code sample to mix multiple WAV files into one output file (Dispose calls omitted for clarity):

public static void MixAudioFiles(IEnumerable<FileObject> input, FileObject output)
{
    var mixer = new WaveMixerStream32 { AutoStop = true };

    foreach (var file in input)
    {
        var reader = new WaveFileReader(file.FullName);

        mixer.AddInputStream(new WaveChannel32(reader));
    }

    WaveFileWriter.CreateWaveFile(output.FullName, new Wave32To16Stream(mixer));
}

But the output file is always twice the size of the input file, despite the use of Wave32To16Stream.

What am I missing here?

Answer 1

Thanks, Mark, that pointed me in the right direction. For anyone else with this issue, here's the working code:

    public static void MixAudioFiles(IEnumerable<string> input, string output)
    {
        var wf = new WaveFormat(16000, 1);

        var mixer = new NAudio.Wave.SampleProviders.MixingSampleProvider(WaveFormat.CreateIeeeFloatWaveFormat(wf.SampleRate, wf.Channels));

        foreach (var file in input)
        {
            var reader = new WaveFileReader(file);

            mixer.AddMixerInput(reader);
        }

        //write the mix file
        WaveFileWriter.CreateWaveFile16(output, mixer);
}

Note that I've omitted the Dispose calls. Make sure to add these to prevent resource leaks.