Elementary/Elementary/Audio/VolumeAdjustedWaveStream.cs

using NAudio.Wave;

namespace Elementary.Audio;

public class VolumeAdjustedWaveStream : WaveStream
{
    private readonly WaveStream _waveStream;
    private readonly float _volume;

    public VolumeAdjustedWaveStream(WaveStream waveStream, float volume)
    {
        _waveStream = waveStream;
        _volume = volume;
    }

    public override WaveFormat WaveFormat => _waveStream.WaveFormat;

    public override long Length => _waveStream.Length;

    public override long Position
    {
        get => _waveStream.Position;
        set => _waveStream.Position = value;
    }

    public override int Read(byte[] buffer, int offset, int count)
    {
        var read = _waveStream.Read(buffer, offset, count);
        try
        {
            for (var i = 0; i < read; i += 2) // 2 bytes per sample
            {
                var sample = (short) ((buffer[offset + i + 1] << 8) | buffer[offset + i]); // convert two bytes to one short (little endian)
                sample = (short) (sample * _volume); // <- anything between 0.0 and 1.0
                buffer[offset + i] = (byte) (sample & 0xFF); // split the short into two bytes
                buffer[offset + i + 1] = (byte) (sample >> 8); // see above
            }
        }
        catch (Exception e)
        {
            Console.WriteLine(e);
        }

        return read;
    }

    protected override void Dispose(bool disposing)
    {
        // _waveStream.Dispose();
        // base.Dispose(disposing);
    }
}