Thank you Tim,What I want is not change voice for single app,but for all application on the machine, I have consider Virtual Audio Cable,But the price is not affordable for me. ----- Original Message ----- From: Tim Roberts To: wdmaudiodev@xxxxxxxxxxxxx Sent: Friday, June 26, 2009 2:23 AM Subject: [wdmaudiodev] Re: How to filter microphone voice? kevinrich47 wrote: Hi all,Is there anyone know how to modify MSVAD sample to make a voice changer?Thank you. Some docs on the web say modify CopyFrom or CopyTo function in the BaseDma.cpp can do this, But I don't know how to do it,Could you please tell me how to start? In general, MSVAD would be the wrong way to do this. To make a voice changer, you need to get input from a real microphone, not a virtual microphone. If you're trying to do this within a single application, you could write a DirectShow filter for this. Alternatively, you may be able to use the Virtual Audio Cable application to do what you want: http://software.muzychenko.net/eng/vac.html -- Tim Roberts, timr@xxxxxxxxx Providenza & Boekelheide, Inc.