jack2-dbus (dummy driver)/qjackctl/alsa_out issue
 

Hi,

I'm working on Arch Linux arm64 with 3.14 kernel. Therefore it doesn't support mmap (used for jack to use alsa driver and zita-a2jbridge, available on 3.17 and newer) but alsa alone is working fine. So I can play music without any problems.

As I want to use jack for calf audio enhancements, i'm trying to make it work. Therefore I installed jack2-dbus,qjackctl and calf.
I added myself to audio group, changed limits (rtprio,memlock,nice), updated asound.conf.


I can start jack/jack2 or jack2-dbus (i tried all of them) without any problem using dummy driver and 2048 Frames/Period. Afterwards I can start alsa_out to bridge between jack and alsa. This is done like "alsa_out -dhw:1 -t1024 -n5" (-t stands for target_delay, n for num_period). This actually works too but stops working after 40seconds (From time to time it was working for up to 3 minutes). Then it sounds strangely, somehow broken, maybe clock is not in sync. When I start alsa_out, before jack2 is running one line of the log says: "clock source = system clock via clock_gettime". CPU usage is always below 10%, cpu gov is ondemand (i tried with performance without luck), the devices are brand-new and with alsa everything works.

Afterwards the only way to make it work again, is to cap all connections in jack. Restart jack and alsa_out (at the same time).

Does anyone of you know that problem? Any idea?

Some details:
Device: Hardkernel Odroid C2 https://www.hardkernel.com/main/prod...=G145457216438
Sound via I2S, PCM5102 https://www.hardkernel.com/main/prod...=G146355616215

/etc/asound.conf
pcm.!default
{
type hw
card 1
period_size 1024
buffer_size 2048
rate 48000
}
ctl.!default{
type hw
card 1
}

EDIT: By the way, i tried to start alsa_out with many different parameters, as well as different asound.conf (using type plug , different buffer sizes etc).


Thanks a lot,
Alex