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Posted 21 Mar 2008

Low Latency Audio using ASIO Drivers in .NET

, 7 May 2008
Demonstrates access to your sound hardware with ASIO drivers
// BlueWave.Interop.Asio by Rob Philpott. Please send all bugs/enhancements to
//  This file and the code contained within is freeware and may be
// distributed and edited without restriction. You may be bound by licencing restrictions
// imposed by Steinberg - check with them prior to distributing anything.

//#include "AsioRedirect.h"
#include "Channel.h"

namespace BlueWave
	namespace Interop
		namespace Asio
			Channel::Channel(IAsio* pAsio, bool IsInput, int channelNumber, void* pTheirBuffer0, void* pTheirBuffer1, int bufferSize)
				// remember the two buffers (one plays the other updates)
				_pTheirBuffer0 = (DWORD*)pTheirBuffer0;
				_pTheirBuffer1 = (DWORD*)pTheirBuffer1;

				// and the size
				_bufferSize = bufferSize;

				// we need one of these to query the driver
				ASIOChannelInfo* pChannelInfo = new ASIOChannelInfo();

				// populated with this
				pChannelInfo->channel = channelNumber;
				pChannelInfo->isInput = IsInput;

				// now we can get the data

				// get channelinfo
				_isInput = pChannelInfo->isInput != 0;
				_name = gcnew String(pChannelInfo->name);
				_sampleType = pChannelInfo->type;

			String^ Channel::Name::get()
				return _name;

			int Channel::BufferSize::get()
				return _bufferSize;

			double Channel::SampleType::get()
				return _sampleType;

			void Channel::SetDoubleBufferIndex(long doubleBufferIndex)
				if (doubleBufferIndex == 0)
					_pTheirCurrentBuffer = _pTheirBuffer0;
					_pTheirCurrentBuffer = _pTheirBuffer1;

			void Channel::default::set(int sample, float value)
				// clip value to avoid problems with conversion.
				if (value > __maxSampleValue)
					value = __maxSampleValue;
				else if (value < -1.0f)
					value = -1.0f;
				// convert float between -1.0 and 1.0 to signed integer
				_pTheirCurrentBuffer[sample] = (DWORD)(value * 2147483648.0f);

			float Channel::default::get(int sample)
				// convert signed integer to float between -1.0 and 1.0
				return (float)((int)_pTheirCurrentBuffer[sample] / 2147483648.0f);

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About the Author

Rob Philpott
United Kingdom United Kingdom
I am a .NET architect/developer based in London working mostly on financial trading systems. My love of computers started at an early age with BASIC on a 3KB VIC20 and progressed onto a 32KB BBC Micro using BASIC and 6502 assembly language. From there I moved on to the blisteringly fast Acorn Archimedes using BASIC and ARM assembly.

I started developing with C++ since 1990, where it was introduced to me in my first year studying for a Computer Science degree at the University of Nottingham. I started professionally with Visual C++ version 1.51 in 1993.

I moved over to C# and .NET in early 2004 after a long period of denial that anything could improve upon C++.

Recently I did a bit of work in my old language of C++ and I now realise that frankly, it's a total pain in the arse.

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