[LAD] JACK and ALSA elucidations

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To: <linux-audio-dev@...>
Date: Friday, February 28, 2014 - 5:58 pm

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Hi LADs

We are working on an ARM based MOD device and while fiddling with JACK some
questions appeared.

I didn't know whether to post on the ALSA os JACK lists, so I decided to
post here :-)

When I start Jack in my PC I get the well know message:

/usr/bin/jackd -P80 -dalsa -r48000 -p128 -n2 -D -Chw:0 -Phw:0

creating alsa driver ... hw:0|hw:0|128|2|48000|0|0|nomon|swmeter|-|32bit

configuring for 48000Hz, period = 128 frames (2.7 ms), buffer = 2 periods

ALSA: final selected sample format for capture: 32bit integer little-endian

ALSA: use 2 periods for capture

ALSA: final selected sample format for playback: 32bit integer little-endian

ALSA: use 2 periods for playback

When starting it on the Beaglebone Black I get:

/usr/bin/jackd --realtime -P80 -dalsa -r48000 -p128 -n2 -Xraw

creating alsa driver ... hw:0|hw:0|128|2|48000|0|0|nomon|swmeter|-|32bit

configuring for 48000Hz, period = 128 frames (2.7 ms), buffer = 2 periods

ALSA: final selected sample format for capture: 32bit integer little-endian

ALSA: use 16 periods for capture

ALSA: final selected sample format for playback: 32bit integer little-endian

ALSA: use 16 periods for playback

- what are those "periods" in the ALSA lines? (2 for the PC and 16 for the
BBB) ? I read a post by Jeremy Jongepier about the Cubieboard2 stating that
the hardcoded values for the Cubie (Minimum number of periods was 4 and
minimum buffer size was 1024) where unfit for realtime operation. Why is
that so?

- on the ArchWiki page on Jack there is a D-bus call

jack_control eps realtime true

stating that it "Sets JACK to realtime mode in its own internal setup."
What is this internal setup? How do I address this when not using D-Bus?

King regards all

Gianfranco Ceccolini
The MOD Team

PS: We will be at LAC againd this year. I'm very eager to meet most of this
distinguished community members there. We have lots of good new for the MOD
in 2014.

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Hi LADsWe are working on an ARM based =
MOD device and while fiddling with JACK some questions appeared.=
I didn't know whether to post on the ALSA os JACK lists,=
so I decided to post here :-)=A0

When I start Jack in my PC I get the well know message:=

/usr/bin/jackd=
-P80 -dalsa -r48000 -p128 -n2 -D -Chw:0 -Phw:0
creating alsa driver ... hw:0|hw:0|128|2|48000|0|0|=
nomon|swmeter|-|32bit
configuring for 48000Hz, period =3D 128 frames (2.7=
ms), buffer =3D 2 periods
ALSA: final selected sample format for capture: 32b=
it integer little-endian
ALSA: use 2 periods for capture
ALSA: final selected sample format for playback: 32=
bit integer little-endian
ALSA: use 2 periods for playbackWhen starting it on the Beaglebone Black I get:

/usr/bin/jackd --realtime -P80 -dalsa -r48000 -p128=
-n2 -Xrawc=
reating alsa driver ... hw:0|hw:0|128|2|48000|0|0|nomon|swmeter|-|32bit=

configuring for 48000Hz, period =3D 128 frames (2.7 ms), buffer =3D 2 perio=
dsALSA: final selected sample format for captur=
e: 32bit integer little-endianALSA: use 16 peri=
ods for capture

ALSA: final selected sample format for playback: 32=
bit integer little-endianALSA: use 16 periods f=
or playback- what are those "pe=
riods" in the ALSA lines? (2 for the PC and 16 for the BBB) ? I read a=
post by Jeremy Jongepier about the Cubieboard2 stating that the hardcoded =
values for the Cubie (Minimum number of periods was 4 and minimum buffer size was 10=
24) where unfit for realtime operation. Why is that so?

=
- on the ArchWiki page on Jack there is a D-bus call

jack_control eps r=
ealtime truestating that it "Sets JACK to realtime mode in its own internal setup."

What is this internal setup? How do I add=
ress this when not using D-Bus?

King regards all<=
div>

Gianfranco CeccoliniThe MOD Team

PS: W=
e will be at LAC againd this year. I'm very eager to meet most of this =
distinguished community members there. We have lots of good new for the MOD=
in 2014.

--089e016347a48ac07e04f37b2d6d--

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Messages in current thread:
[LAD] JACK and ALSA elucidations, Gianfranco Ceccolini, (Fri Feb 28, 5:58 pm)
Re: [LAD] JACK and ALSA elucidations, Jeremy Jongepier, (Fri Feb 28, 8:01 pm)
Re: [LAD] JACK and ALSA elucidations, Gianfranco Ceccolini, (Mon Mar 10, 1:51 pm)
Re: [LAD] JACK and ALSA elucidations, Alex Gagnon, (Mon Mar 10, 2:34 pm)
Re: [LAD] JACK and ALSA elucidations, Paul Davis, (Mon Mar 10, 2:50 pm)
Re: [LAD] JACK and ALSA elucidations, Paul Davis, (Mon Mar 10, 2:26 pm)
Re: [LAD] JACK and ALSA elucidations, Gianfranco Ceccolini, (Wed Mar 12, 2:26 am)
Re: [LAD] JACK and ALSA elucidations, Paul Davis, (Wed Mar 12, 2:50 am)
Re: [LAD] JACK and ALSA elucidations, Gianfranco Ceccolini, (Wed Mar 12, 3:21 am)
Re: [LAD] JACK and ALSA elucidations, Paul Davis, (Wed Mar 12, 12:12 pm)
Re: [LAD] JACK and ALSA elucidations, Jeremy Jongepier, (Wed Mar 12, 11:37 am)
Re: [LAD] JACK and ALSA elucidations, Paul Davis, (Fri Feb 28, 6:12 pm)