26 Dec
2022
26 Dec
'22
1:22 a.m.
Someone on the Ardour forums reported very strange zita_a2j behavior recently, where
the signal level is much higher when using zita_a2j or the zalsa_in internal client than
it is
when using jackd directly.
I suggested that poster describe the problem on the LAU list, but he was still not able to
get a list join confirmation from attempting to add his address to the list yet.
I have also managed to duplicate the problem, so I will link to the original problem
description, then describe my setup and observed behavior.
Originally posted as "Zita-a2j is way too hot!" here:
https://discourse.ardour.org/t/zita-a2j-is-way-too-hot/108040/6[1]
My setup:
My setup:
Lexicon USB interface as primary
Focusrite Solo (also USB) as second interface
My typical settings for primary interface:
48k sample rate, 1024 frames/period, 3 periods/buffer
Process to duplicate:
Started Lexicon interface with qjackctl, 48k/1024/3 settings.
Using JK meter to measure levels, K20 scale.
Connected both channels of Lexicon to JK meter, set level so that
average from synth note was around 0, peaking around +10.
Stopped jackd on Lexixon, started jackd on Focusrite, and set level so
that single channel of synth connected to Focusrite input was
approximately the same.
After stopping jackd on Focusrite, starting jackd on Lexicon again,
verified that left channel was still at same amplitude as previously verified.
Loaded zalsa_in for Focusrite Solo interface with:
jack_load Solo zalsa_in -i "-d hw:USB -r 48000"
Connecting Focusrite input from zalsa_in to JK Meter showed just idle output
noise level at around -5dB, with peaks around +8 dB. Synth note is still
around 0dB on Lexicon channel, but is now at least +18 dB in zalsa channel.
I verified the same behavior when explicitly giving a period size with:
jack_load Solo zalsa_in -i "-d hw:USB -r 48000 -p 512 -n 3"
I see exactly the same behavior when using zita-a2j as the client with:
zita-a2j -d hw:USB -r 48000 -p 512 -n 3
I have the latest released jackd version:
$ jackd --version
jackdmp version 1.9.21
The jackd build is from the Fedora repository, although they usually do a pretty good job
not breaking anything in the build. The original report was using Ubuntu 22.04. I think
that release of Ubuntu has jackd 1.9.20, which seems to indicate this is not a
distribution
specific problem.
My previous experience with Fons's software is that it is pretty bullet proof, so
I'm
surprised to see the same strange behavior out of zita-a2j.
I don't see anything unusual in the way the devices are opened, looks like standard
format
S243LE for the older Lexicon device and S32LE for the newer Focusrite device:
Card 0 (Lambda):
* Playback Device 0 (USB Audio):
- Subdevice 0 (hw:Lambda,0,0):
used by: jackdbus (PID 121752)
access: MMAP_INTERLEAVED
format: S24_3LE
subformat: STD
channels: 2
rate: 48000 (48000/1)
period_size: 1024
buffer_size: 3072
* Recording Device 0 (USB Audio):
- Subdevice 0 (hw:Lambda,0,0):
used by: jackdbus (PID 121752)
access: MMAP_INTERLEAVED
format: S24_3LE
subformat: STD
channels: 2
rate: 48000 (48000/1)
period_size: 1024
buffer_size: 3072
Card 2 (USB):
* Playback Device 0 (USB Audio):
- Subdevice 0 (hw:USB,0,0):
closed
* Recording Device 0 (USB Audio):
- Subdevice 0 (hw:USB,0,0):
used by: zita-a2j (PID 130423)
access: MMAP_INTERLEAVED
format: S32_LE
subformat: STD
channels: 2
rate: 48000 (48000/1)
period_size: 512
buffer_size: 1536
Any thoughts on what is going on, or how to debug?
--
Chris Caudle
--------
[1] https://discourse.ardour.org/t/zita-a2j-is-way-too-hot/108040/6