Opening and Closing Mixer Devices
When you want to use a mixer device, you can either simply begin using it or
you can explicitly open the device before using it. Explicitly opening a mixer
device offers two main benefits:
- It guarantees the continued existence of that mixer device.
- It lets you receive notification of audio line and control changes.
You can use the mixerOpen
function to explicitly open a mixer device. This function takes as parameters
a device identifier, a pointer to a memory location, and other values unique to
each type of device. The memory location is filled with a device handle. Use
this device handle to identify the open mixer device when calling other audio
mixer functions. As long as a handle of a mixer device exists, the device
continues to exist in the system. If a configuration change occurs to the mixer device
and it hasn't been explicitly opened, your application might suddenly be
unable to access it.
The difference between device identifiers and device handles is important.
Device handles are returned when you open a device driver by using mixerOpen
. Device identifiers are determined implicitly from the number of devices
present in a system; this number is obtained by using the mixerGetNumDevs
You can use the mixerClose
function to close a mixer device. You should close the device after you finish
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