Definitions of different audio hosts

I’m sorry to be so dumb, but I’ve read all I can find on Microsoft Sound Manager and Windows WASAPI and I can not understand what they do and when to use them. Will some one please explain them in really simple terms please? I’m not an audio engineer, but I’d like to record songs from both sounds playing on my speakers and from records and tapes. I know I have to switch between line in and stereo mix but what do the above Sound Manager and WASAPI should I use? I’ve been using the default MME but then I get lost.

Thank you.


See this page in the Audacity Manual:


I’ve been to your suggested site and nothing makes sense. I tried using Windows WASAPI and Microsoft Sound Mapper and I can’t get Audacity to record anything with either of them chosen. I still need a simple explanation of each of them and when to use them. Thanks anyway.


I’m using Win7 Pro SP1 and Audacity 2.1.1

I don’t claim to understand it all, but these are “driver models” or “driver protocols” defined by Microsoft.

Your audio hardware will work with one or more of those standards, depending on the hardware and driver.

There is another standard called ASIO that was developed by Steinberg, and it only works with pro audio hardware and pro audio software.

The driver sits in-between the application and the hardware, basically acting as in interpreter… The application talks to the driver and the driver talks to the hardware. For example, the standardization means that any Windows word processor program can work with any printer. Or that any Windows soundcard can work with any Windows audio application.

The driver is “traditionally” supplied by the hardware manufacturer, because only the hardware manufacturer knows how to communicate with the hardware. The hardware manufacturer also knows how to make the driver communicate with Windows (by following one of those protocols), and the the application developer knows how to communicate with Windows (and with a Windows driver).

There are some standard drivers supplied by Microsoft so the hardware manufacturer can optionally make their hardware work with these. For example, many USB soundcards (or other audio devices) are Plug-and-Play with the standard Windows drivers.

I know all of what you said but you didn’t tell me what WASAPI and Sound Mapper do and when I should use them. Henry

Sound Mapper is a “virtual device”. Windows uses one input device and one output device at a time. You can think of Sound Mapper as just another name for whatever devices Windows is currently set to use.

WASAPI is complicated; it’s the “Windows Audio Session API”. Put as simply as I can, it is one of the “sound systems” available to the Windows operating system. Whereas MME is an old an well tested sound system, WASAPI is the new one that was introduced with Windows Vista. It has one very useful feature which is the “loopback” feature. Many newer sound cards don’t support “Stereo Mix” for recording what is playing on the computer, but that’s what “WASAPI loopback” allows you to do.
More about WASAPI in these links:

WASAPI loopback is generally the best way to record sounds that are playing on your computer (Windows Vista and later). See here for details:

MME is the most reliable way to record other inputs.

It sounds to me like I aught to just stay with MME and switch between line in and stereo mix for my simple recording requirements. When I tried using WASAPI and sound mapper I couldn’t get Audacity to record anything. Just a straight line. Thanks. Henry

We generally recommend WASAPI loopback because few modern computers have Stereo Mix, but if Stereo Mix works for you, then go ahead and use it. The general advice is, use whatever works best for you.