[arm-allstar] NEW: simpleusb driver updates

[David McGough]

Everyone,

Working to further improve/reduce audio latency, I've improved how the 
simpleusb driver sends audio to the CM1XY USB sound device.

Now, the simpleusb.conf parameter "duplex=[0|1]" is implemented.  
Previously, this parameter had no effect, it has always only been a
placeholder. Now, the default configuration is "duplex=1"  for all nodes.
If you wish to continue to use the original code for any reason, set
"duplex=0".

With "duplex=1" (the new default) enabled, the simpleusb driver continues
to send frames of silence to the audio adapter at all times; even when the
transmitter (PTT) isn't active. This reduces the impact of the variable 
start-up latency issues which simpleusb has classically exhibited.

Note that by sending audio frames continuously, the activity LED
pattern you'll see on the CM1XY device has changed, too.

This software update is in this morning's release. Please use pacman to 
update your systems when convenient---admin menu option #1.

Also, you can check the dynamically updated release notes (which are 
included on the RPi2/3 in the file: /etc/allstar_version) at this URL:

https://hamvoip.org/local/allstar_version.php


Thanks,


73, David KB4FXC