[LAD] Document on using Jack Apps

[Arvind Venkatasubramanian]

On Mon, Aug 2, 2010 at 4:23 AM, <fons at kokkinizita.net> wrote:

> On Sun, Aug 01, 2010 at 11:06:36PM -0400, Arvind Venkatasubramanian wrote:
>
> > Everytime I changed the qJACKctl parameter settings, I "DID"  stop Jackd,
> > quited Jack,
>
> What do you mean by 'quited Jack' ? Are you running jackd in a terminal ?
> Then Qjackctl's settings  will not affect it. Just use the Start/Stop
> buttons in Qjackctl.
>
> Also check your sound card mixer. Make sure you don't loop back the input
> to output there. And use Jaaa to check the input signal - it could be
> clipping. You should see 7 frequencies, the strongest at FS/16, and the
> six others at lower level and frequency (or just compare the the output
> of Jdelay).
>
> 10 ms latency at 8 khz will be difficult, just a good antialising
> filter will produce something like that. No problem at 48 kHz.
>
> Ciao,
>
> --
> FA
>
> ====================================================================

Using Jdelay for fs = 8 KHz, I am measuring 6.359 ms and for 16 KHz, 3.466
ms without Xrun interrupts.  But I need to verify this with JAAA as per your
idea but I am having issues there.

[Arvind at laspr-01 ~]$ jackd -r -d alsa -r 16000 -n 1 -p 32 -S 16 -s -H -M
jackd 0.118.0
Copyright 2001-2009 Paul Davis, Stephane Letz, Jack O'Quinn, Torben Hohn and
others.
jackd comes with ABSOLUTELY NO WARRANTY .  This is free software, and you
are welcome to redistribute it
under certain conditions; see the file COPYING for details

JACK compiled with System V SHM support.
loading driver ..
apparent rate = 16000
creating alsa driver ...
hw:0|hw:0|32|2|16000|0|0|hwmon|hwmeter|soft-mode|16bit
control device hw:0
configuring for 16000Hz, period = 32 frames (2.0 ms), buffer = 2 periods
ALSA: final selected sample format for capture: 16bit little-endian
ALSA: use 2 periods for capture
ALSA: final selected sample format for playback: 16bit little-endian
ALSA: use 2 periods for playback
jack main caught signal 15

[Arvind at laspr-01 ~]$ jack_delay
capture latency  = 32
playback_latency = 32
Signal below threshold...
Signal below threshold...
Signal below threshold...
Signal below threshold...
Signal below threshold...
Signal below threshold...
Signal below threshold...
   152.708 frames      3.463 ms ?? Inv
   152.826 frames      3.465 ms Inv
   152.824 frames      3.465 ms Inv
   152.823 frames      3.465 ms Inv
   152.821 frames      3.465 ms Inv
   152.834 frames      3.466 ms Inv
   152.821 frames      3.465 ms Inv
   152.832 frames      3.466 ms Inv

After starting Jack, I am able to run Jdelay.  But I am not able to run
JAAA

[Arvind at laspr-01 ~]$ jackd -r -d alsa -r 16000 -n 1 -p 32 -S 16 -s -H -M
jackd 0.118.0
Copyright 2001-2009 Paul Davis, Stephane Letz, Jack O'Quinn, Torben Hohn and
others.
jackd comes with ABSOLUTELY NO WARRANTY This is free software, and you are
welcome to redistribute it
under certain conditions; see the file COPYING for details

JACK compiled with System V SHM support.
loading driver ..
apparent rate = 16000
creating alsa driver ...
hw:0|hw:0|32|2|16000|0|0|hwmon|hwmeter|soft-mode|16bit
control device hw:0
configuring for 16000Hz, period = 32 frames (2.0 ms), buffer = 2 periods
ALSA: final selected sample format for capture: 16bit little-endian
ALSA: use 2 periods for capture
ALSA: final selected sample format for playback: 16bit little-endian
ALSA: use 2 periods for playback

[Arvind at laspr-01 ~]$ jaaa -A -d hw:Intel -r 16000
Alsa_driver: Cannot open PCM device hw:Intel for playback.
Alsa_driver: Cannot open PCM device hw:Intel for capture.
Can't connect to ALSA
[Arvind at laspr-01 ~]$ jaaa -J -d hw:Intel -r 16000
Connected to JACK with 4 inputs and 4 outputs
mlockall: Cannot allocate memory
Closing JACK...
[Arvind at laspr-01 ~]$

However for higher sampling rates, I am able to open JAAA without even
issuing jackd command to start JACK separately.

[Arvind at laspr-01 ~]$ jaaa -A -d hw:Intel
playback :
  nchan  : 2
  rate   : 48000
  frsize : 1024
  nfrags : 2
  format : S32_LE
  capture  :
  nchan  : 2
  rate   : 48000
  frsize : 1024
  nfrags : 2
  format : S32_LEsynced
Connected to ALSA with 2 inputs and 2 outputs
Can't create ALSA thread with RT priority
mlockall: Cannot allocate memory
Closing ALSA...
[Arvind at laspr-01 ~]$

While JAAA is running, I am not able to start Jdelay.  Once JAAA operates
alongside other Jack applications, I will be able to patch the output of
Jdelay to JAAA and see if I can see those 7 tones that you internally use in
Jdelay for latency measurements.  Can you please suggest some inputs here?

Regards,
Arvind V
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