[alsa-devel] UAC2 clock selector for AudioBox 1818VSL

[Daniel Mack]

Hi,

On 06.09.2012 22:20, louis at museresearch.com wrote:
> Hi!
>   I'm attempting to get the "Clock Selector" mixer control to work with
> the PreSonus AudioBox 1818VSL (a UAC2 device).
>
> The control shows up in amixer as an enumerated value, but I don't seem to
> be able to set it (I've tried amixer, alsactl, and setting it
> programmatically). The possible values are correct (listing Internal
> Clock, S/PDIF Clock, and ADAT Clock as possible options); It just doesn't
> appear to take my setting, by which I mean amixer doesn't update the
> settings, I still have the occasional click when the sampling rates match
> over S/PDIF and I attempt to use external sync. No error is returned.
> 
> After digging around USB specs and ALSA's usb/mixer.c and being unfamiliar
> with both the USB audio spec and the inner workings of ALSA, I thought
> it'd be best to ask the list about this: How would I check to see if ALSA
> is asking the device to change clock source at all?

Hmm. A clock selector is handled like any other control entity on the
hardware. Some thoughts:

- Are you able to control other settings like the volume?

- It's fairly common for devices to not accept a new clock source
setting if they can't lock to the external source within some time. Did
you connect anything to the digital inputs?

- Are you able to control that setting with the native Mac OS X driver?
(IOW, without installing a 3rd-party driver)

Also, please send the output of "lsusb -v" for that device.


Daniel