Control Windows sound volume

Question

Hi,

our software should play sounds (not just small noises, but voice etc.). I wonder what about the volume control. The Windows Vista style guide lines says to define an application specific volume control in the windows mixer.

But what about Windows XP and below? I don't think there is a way to get our control into the Windows mixer. BUT you can implement your own volume control, but if you don't modify the audio data, it cannot go louder than system wide volume (which might be very low or even mute). The question is: should an application use it's own volume control or trigger the windows volume control? The problem is, that basic user doesn't even know where to setup the volume in windows.

Regards, uwe

Answer 1

Our application needs to output voice as well, and also have different volume settings relative to other applications that may be running at the same time. We have a volume control that the user can change from within the application.

As such, in Windows 2000/XP, we do modify the system volume when our application gains focus, and set it back to the previous setting when we lose focus or when then application shuts down. This does work well, and does not seem to interfere with the workings of other audio based applications running at the same time (such as speech recognition software which is very sensitive to recording volume for example).

This is exactly the same behaviour as Vista and Windows 7, except that they do the work of maintaining the individual volume levels for each application (and in this case we disable the previously mentioned code).

Answer 2

In my application (a software synthesizer/music composition tool) I actually don't touch the system volume or even offer a volume control for my own application. All my audio output is normalized to about 95% of the max possible level, and from that point the user can control the output volume either with the Windows volume control or the volume control on their speakers.

In my opinion, this is how a Windows audio application like this should behave, because typically when a software synthesizer is used it's the only application producing audio output, and the user already has two other ways of controlling volume (the Windows control and the speaker knob).

In the case of an application like yours, which is meant to play sounds in an environment where other applications may be making noise also, I think your application should only offer a way of lowering its own volume, without affecting the system volume. Most Windows users already know where the system volume control is (lower right toolbox), so it's kind of superfluous to add this control to your own application as well.

Answer 3

Most audio rendering frameworks (you don't mention which one you use) allow the user to control the audio of the stream passed from the audio rendering framework to the system audio engine. For example, DirectSound has a method IDirectSoundBuffer that allows you to set the volume for that sound buffer.

Per-application volume control (whether it's exposed via the system mixer or not) is a dramatically better experience for customers than an application controlling the master volume. Many machines (most current laptops for example) don't provide hardware volume controls and depend on the user to set the master volume to a comfortable level (which is a highly user specific value). If your application manipulates the master volume you're overriding the user choice and they're likely to be upset.

Btw, to be clear: I have no issues with MusiGenesis' choices either. For the specialized example of his application, that choice makes sense. Another similar example to MusiGenesis' example is a MIDI rendering application. If the application sometimes renders through hardware MIDI (with no volume control) and sometimes through software MIDI (with a volume control) it may make sense not to expose the volume control to the user to avoid confusion.