Q: Our application uses the Sound control panel to allow the user to configure the sound input device and its settings. However, when we launch our application under Mac OS 9, the user can no longer use the Sound control panel to configure their sound input settings while our application is running. What’s going on?

A: With Mac OS 9.0 the Sound control panel is just a regular application and has no special privileges. The Sound control panel uses the standard sound API to adjust the driver’s settings. The sound input drivers are enforcing the access mode in which they were opened. If you open the sound input driver for recording (writing as opposed to reading), no other application can open the driver and make changes to its settings.

Just as you would not want a second sound application adjusting your recording settings while your application was running, you don’t want the Sound control panel adjusting the recording settings either.

The best solution to this is to have the user configure the sound settings from your application. You can present whatever interface you would like to do this—one that’s consistent with your application. The second option, which is a poor choice, would be to have the user configure the settings in the Sound control panel before launching your application.

There is also the possibility of using QuickTime for all of your recording needs and in doing so using the Sequence Grabber as your API for configuring the input settings.

[Oct 05 1999]

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