The virtual audio utility enables developers to interactively configure/control virtual audio Composite devices, through the virtual_audio driver.
Flags specified before --add modify the specification of the device that will eventually be added.
The --add flag creates the device according to that spec “blueprint” and adds it to devfs where it can be detected by an audio service, tool, test or other client. Conversely, the --remove flag removes a previously added device from the system. After a device is removed, it is no longer shown in devfs; any client FIDL connections will drop in short order.
Flags specified after --add modify the device's behavior in realtime, such as slightly change its clock rate, emulate a plug state change, etc.
The --wait option can be used to execute commands one at a time, waiting for a key press before proceeding. This is useful for observing the types of realtime changes mentioned above.
Note: without --wait, the utility exits after applying the final flag, dropping all FIDL connections (thus removing all virtual audio devices).
For example:
$ virtual_audio --domain=1 --add --wait --rate=1000 --wait
Executing `--domain' command...
Executing `--add' command...
Executing `--wait' command...
Press Q to cancel, or any other key to continue...
(user observes the device's initial clock rate, then presses a key)
Executing `--rate' command...
Executing `--wait' command...
Press Q to cancel, or any other key to continue...
(user observes the device's clock rate has changed, then presses a key)
$ virtual_audio --domain=1 --add --wait --unplug --wait
Executing `--domain' command...
Executing `--add' command...
Executing `--wait' command...
Press Q to cancel, or any other key to continue...
Executing `--unplug' command...
Executing `--wait' command...
Press Q to cancel, or any other key to continue...
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