Thanks. I found autojack, and know just enough Python to make some sense of it. I am still confused as to where autojack is getting the 64 value. I easily found...

                procin = subprocess.Popen(
                    ["/usr/bin/zita-a2j", "-j", f"{ldev}-in", "-d", f"hw:{ldev}", "-r", dsr, "-p", def_config['ZFRAME'],
                     "-n", def_config['PERIOD'], "-c", "100"], shell=False)

...which would seem to pull the -p parameter from the def_config array. And I see that it's default value is 512, set early on in the code. However, I assume this value is over ridden by my saved session setting of 128 at some point when the code gets going. Where is the 64 coming from? Maybe ZFRAME is set by the GUI to half frames?

In some ways Python does make life easier than C. I can just edit the file with a "* 2" or "* 4", log out and back in again and go. I assume you are part of the group of people behind this project... so thank you!

-Ethan

On Sat, 2020-06-13 at 17:12 -0700, Len Ovens wrote:
On Sat, 13 Jun 2020, Ethan Funk wrote:

That leads me to a question regarding Ubuntu Studio Control, which I have been
using to manage jackd and additional audio interfaces via zita-a2j. I have Ubuntu
Studio Control configured to use a Tascam US-4x4 as the main audio interface with
128 sample process frames at a 48 kHz sample rate on my test machine, with the
built-in audio port on the motherboard as a a2j/j2a bridge. Audio to and from the
motherboard interface is broken up with the zita-a2j and zita-j2a running as
launched by Ubuntu Studio Control. Notably, the -p run option is set to 64. If I
run zita-a2j myself with -p set nice and high, to 1024 for example, I get good
clean audio, at the expense of latency on that interface. That's fine for me,
since I still have good, low latency on the main interface. Does any one know
where I can find the source code for Ubuntu Studio Control so I can investigate a
fix to make this settable?

-controls is written in python and so easy to change. You can view the 
source directly by looking at /usr/bin/autojack. Zita-ajbridge has the 
buffer to 1/2 that of jack... but that is proving to be a problem in some 
cases. Internal should be at least 128 and hdmi should be 4096. The git 
repo is 
https://github.com/ovenwerks/studio-controls
 (it has been 
"unbranded" so other distros can feel free to use it)

This is a relatively new project and so is very much not bug free. Being 
able to directly set buffer size for each device used sounds very much 
like a reasonable feature request. (also a feature that has been thought 
of before)

Be aware that autojack runs from session start and because of the way some 
DEs use systemd/logind to start sessions... the session never really ends 
so a reboot or a killall autojack may be needed to see how changes do. I 
would suggest running autojack in a terminal while testing new code so 
that you have access to terminal output. once you have finished with the 
code running studio-controls should restart it in the background again if 
you have closed the terminal.


--
Len Ovens
www.ovenwerks.net

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