Hi Jerry, Yes, the UI would be for routing/levels and visualization (VU meters), it would not have to process the audio stream. My first reaction to your suggestion was to wonder why I didn't think of it. But after thinking about, I wonder: A C++ dll will run in the process space of the caller, a .NET app, and all the threads created will belong to that process. When the .NET gc runs and "suspends all threads", will it know not to suspend the thread that was created by the C++ dll for callbacks from, say, an ASIO driver? I have not run across the information that would allow me to answer this question. It seems possible that the CLR would suspend all the threads of the process, and glitches would occur at low latency. It is also possible that the CLR would be smart enough to know not to. Does anyone know the answer to this question? Or where to go to find out the answer? I'll check out the blog. - Andy ________________________________ From: wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Jerry Evans Sent: Thursday, February 26, 2009 11:54 AM To: wdmaudiodev@xxxxxxxxxxxxx Subject: [wdmaudiodev] Re: very low latency audio and a C# UI? Andy Just to clarify - if your DSP code is C++, then what role for the C# components. Is the UI control only (routing/levels/etc) or is the UI a more active participant: does it actually have to process the audio stream in some way? I'd package the DSP code into a C++ DLL and export a narrow API for the C# code to call. Your primary audio thread is created within the DLL and has a signalling/control mechanism based on shared events or somesuch. That is all pretty easy to organise. I think you could get read access to the audio stream without too much trouble as well - treat the C# audio sink as a slow output device to account for GC and interop overhead etc. The blog here might be of interest: http://geekswithblogs.net/robp/archive/2008/08/13/speedy-c-part-3-unders tanding-memory-references-pinned-objects-and.aspx HTH & keep us posted - I'm sure we'll have to face this issue before too long. Jerry Voelkel, Andy wrote: Hi Tim, Thanks. That helps, just to know it is possible. One of the things I don't know how to do create an "unmanaged threads". I was under the impression that threads themselves aren't managed or unmanaged, only code was. And therefore I don't know how to arrange it so that the gc knows that my low latency thread doesn't contain unmanaged code and thereform doesn't suspend it". Do you have any book or other reading recommendations that would enlighten me on such issues? - Andy CONFIDENTIALITY NOTICE: This e-mail transmission, and any documents, files or previous e-mail messages attached to it, may contain information that is confidential and/or legally privileged. If you are not the intended recipient, or a person responsible for delivering it to the intended recipient, please DO NOT disclose the contents to another person, store or copy the information in any medium, or use any of the information contained in or attached to this transmission for any purpose. If you have received this transmission in error, please immediately notify the sender by reply email or at mailto:privacy@xxxxxxxxxxxxxxx, and destroy the original transmission and its attachments without reading or saving in any manner. For further information about Plantronics - the Company, its products, brands, partners, please visit our website www.plantronics.com.