DSSCL_EXCLUSIVE not giving exclusive audible output. DirectSound

Question

Hi guys,

Very simple question. In the MSDN documentation for the DirectSound API they state that when my application is in focus it will be the only audible program. This is exactly what I want to happen, however when setting this flag and playing sound through my application, I can still hear the background music on my computer.

So the question is, why? Is it because the application playing the background music using a different low level API, and thus different mixing buffers? Or is there some other little trick i need to tweak in order to become the only audible application.

I asked a similar/related question here, with no response. But once again if you don't know the answer to the specific DirectSound question, but you know a way of becoming the only audible application with a different API let me know!

Thanks, I'm on Windows XP 32Bit Professional, if it makes a difference.

Answer 1

A long time ago, the Windows developers realized that allowing one application to have total control of the audio system (whereby muting other apps) was a bad idea. And then they subsequently deprecated many of these "exclusive" and foreground/background mode flags. I believe this behavior change goes all the way back to DirectX 7.1 (WinME) and then formally everywhere on DX 8. This was 10 years ago.

Imagine your video conferencing app becoming muted when you switched the foreground application to an app that ran audio in some sort of exclusive mode. Not being able to reliably hear anyone when switching between apps is not a great experience.

As a matter of fact, prior to DX 8, many popular voice-comm apps for multi-player gaming would continually sniff for the foreground window handle and use that for the call to SetCooperativeLevel such that they wouldn't get muted.

I think it would be interesting to know, "what is that you really want to do?" that makes you assume you need total control of the audio output.

On Vista and higher, there is the WASAPI api for low-level audio. I believe there is a concept of "exclusive" mode but I don't know if trumps other apps using the sound card. YMMV.