Thank you Sam, I only need to change the microphone input voice(for default input device), I found some thread on other forum/list say that modify CMiniportWaveCyclicStreamMSVAD::CopyFrom function of MSVAD sample can do this job, what do you think? also,Could you please take look at"av voice changer" software? this product are very much the same with my new product. after installed that product,Open Device manager -> Sound,Video and Game Controller -> Avnex Virtual Audio Device -> Properties -> Driver -> Driver Details in Driver files, from top to bottom there is drmk.sys ks.sys portcls.sys stream.sys vcsvad.sys (important) ksproxy.ax ksuser.dll wdmaud.drv if you open the MSVAD(simple) properties, this sequence will be same except the vcsvad.sys line changed to vadsimpl.sys, so,I think that driver is base on MSVAD. Thank you very much. ----- Original Message ----- From: Sam Tertzakian To: wdmaudiodev@xxxxxxxxxxxxx Sent: Friday, June 26, 2009 11:39 AM Subject: [wdmaudiodev] Re: How to filter microphone voice? Hi, If you want to change the audio for all possible streams/devices under 2000/XP, then the best choice is a WDM "lower filter" driver that sits under KS.sys. The driver will pass all requests unmodified. However, for reads and writes it will modify the data. For writes, your driver will receive a WRITE IRP and will modify the data (change voice) and then submit the same IRP with modified data down to the next driver in the stack. For READ IRPS it will set a completion routine, then pass the IRP down to the next driver in the stack. When the lower driver has filled the IRP's buffer with audio, the IRP will arrive in your completion routine. There you may modify the data that was read and then complete the IRP which will send it to the application. Keep in mind the following: 1. This architecture will work for 2000/XP/Vista/Windows 7. The same binary should work. 2. This driver is a WDM Filter Driver. Do not confuse this with a DirectShow filter which is unrelated to this. 3. Because it is WDM Filter Driver, it is not an "audio driver" per se, as it is a straight filter driver. So, the information that is relevant in the DDK is in two places: a) WDM Filter Drivers b) Kernel Streaming Drivers. You need b) because the data format passed in the IRPs is passed from KS so you need to understand the data formats in the IRPs. I can tell you with certainty that all of what I am saying works, because I have personally done this. One more thing...what you want to do is not trivial. There are some details I left out. For example, when you receive data buffers, they just contain audio data. But, buffers themselves have no information about things like: how many channels are being processed, how many bits/bytes per sample and the sample rate. So, some of the requests that go through your driver, while they remain unmodified as you pass them down, must be read by your driver and tracked so that you know when a device is opening and closing, and what parameters are used to open the device. There are also other technical details such as: you will need to properly lock down the memory before you read and write to it in some cases, but not all...if I recall the buffers passed are of the type METHOD_NEITHER, which requires special attention. If you need some help along your journey, I am willing to help; as I am sure others here are. It is not an easy task; but, once you complete it, I am sure you will be very proud of your achievement. From: wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of kevinrich47 Sent: Thursday, June 25, 2009 7:05 PM To: wdmaudiodev@xxxxxxxxxxxxx Subject: [wdmaudiodev] Re: How to filter microphone voice? Hi,Could you please tell me which technology in Microsoft is the best choice to implement a voice changer?Thank you . ----- Original Message ----- From: Frank Yerrace To: wdmaudiodev@xxxxxxxxxxxxx Sent: Friday, June 26, 2009 9:29 AM Subject: [wdmaudiodev] Re: How to filter microphone voice? Note that the only appropriate way to distribute an LFX is as part of a complete audio driver package. Of course, if this is just for experimentation/proof of concept then do whatever you want. Frank Yerrace Microsoft Corporation This posting is provided "AS IS" with no warranties, and confers no rights. From: wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Tim Roberts Sent: Thursday, June 25, 2009 5:42 PM To: wdmaudiodev@xxxxxxxxxxxxx Subject: [wdmaudiodev] Re: How to filter microphone voice? kevinrich47 wrote: 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. Oh, come on! There's a free version with some features limited for you to try out, and the full version is only $30. If you have not done audio drivers before, it will save you MONTHS of frustration. If you are working on Vista, you can write a Local Effects Audio Processing Object (LFX APO) to do this. This is a user-mode DLL that lives in the the audio engine process. There is a sample in the WDK in src\audio\sysfx. It's a little bit tricky to get one installed to begin with, but there are documents available to help with that. -- Tim Roberts, timr@xxxxxxxxxxxxxxxxxxx & Boekelheide, Inc.