AudioBuffer.cs

using System.Runtime.InteropServices;
using Whisper;

/// <summary>This class demonstrates how to implement iAudioBuffer COM interface in C#, to supply audio samples produced by managed code</summary>
/// <remarks>The library requires these samples to be <c>float</c> numbers @ 16 kHz sample rate</remarks>
sealed class AudioBuffer: iAudioBuffer
{
	void IDisposable.Dispose()
	{
		free();
		GC.SuppressFinalize( this );
	}
	~AudioBuffer()
	{
		free();
	}
	void free()
	{
		Marshal.FreeCoTaskMem( mono );
		mono = IntPtr.Zero;
		length = capacity = 0;
	}

	/// <summary>Allocate buffer of the specified length in unmanaged memory</summary>
	public void allocate( int len )
	{
		if( len <= capacity )
		{
			length = len;
			return;
		}
		Marshal.FreeCoTaskMem( mono );
		mono = Marshal.AllocCoTaskMem( len * 4 );
		if( mono == IntPtr.Zero )
			throw new OutOfMemoryException();
		length = capacity = len;
	}

	/// <summary>Use this span to write data to the internal buffer</summary>
	public Span<float> pcmMono
	{
		get
		{
			if( 0 != length )
			{
				unsafe
				{
					return new Span<float>( (void*)mono, length );
				}
			}
			return Span<float>.Empty;
		}
	}

	IntPtr mono = IntPtr.Zero;
	int length = 0;
	int capacity = 0;
	public TimeSpan timestamp { get; set; } = TimeSpan.Zero;

	int iAudioBuffer.countSamples() => length;
	/// <summary>Provide unmanaged pointer to C++ code</summary>
	IntPtr iAudioBuffer.getPcmMono() => mono;
	/// <summary>This class doesn't support stereo PCM, that's why always returns <c>null</c>.</summary>
	/// <remarks>This means it’s not compatible with diarize feature</remarks>
	IntPtr iAudioBuffer.getPcmStereo() => IntPtr.Zero;

	void iAudioBuffer.getTime( out TimeSpan time ) => time = timestamp;
}