19 Sep
2017
19 Sep
'17
8:59 p.m.
On 09/19/2017 01:44 PM, Len Ovens wrote:
In my opinion, run jackd as your audio backend and use
PA only as a
desktop front end bridged to jack.
Yeah, that seems to be the best course of action. I set QJackCtl to load
on KDE startup and put this in Options > Execute script after Startup in
QJackCtl's settings:
pactl load-module module-jack-sink channels=18; pactl load-module
module-jack-source channels=18; pacmd set-default-sink jack_out
That tells PulseAudio to send audio to JACK by default. (On Fedora I had
to install pulseaudio-module-jack for that). Configuring PulseAudio to
not load its ALSA backend would be annoying because I sometimes use my
onboard sound card on my laptop outside of home (not for music,
generally for hearing speech in videos).
But this is still annoying because JACK won't start when I plug in the
Ultralite AVB until I wait a few seconds. Plus I have to make sure the
Ultralite AVB's sample rate is set to the same sample rate I have JACK
configured for, and if not, change it with the controls on the Ultralite
AVB.
Pulse should be started with both the
ALSA and udev modules unloaded (or they should be
unloaded prior to
bridging to jack). I have in the past used the PA -jackdus-detect
module, but now have a script that loads the jacksink/source modules the
way I want. It is important that PA does not see any physical device
when using jackd as PAs audio IF. The reason for this is that if PA can
find any device it will use sync from it and that device will limit the
jack master device to the device PA is synced to and (at least in my
case) not allow jackd to freerun properly.
So Ardour export with PA bridged and PA can see the internal (HDA) audio
IF equals crash. But if PA has no ALSA module loaded, everything is fine
and reliable. If you wish to send PA's output to another IF besides the
jackd master, use ALSA_out or zita-j2a to make it another jack output
and run it through jackd. There can be as many PA to jackd bridges as
you need (want) so that the movie you are watching can go through one IF
and the skype call through another.
By running jackd as the PA backend, you present PA with a "sound card"
that has a SR it knows it can't change (48k or whatever) and will do
what it needs to for the input and output to match.
--
Len Ovens
www.ovenwerks.net
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