26 Jul
2016
26 Jul
'16
2:29 p.m.
Hi,
I'm trying to get receive audio data from a USB software defined radio and
pipe it through jack to alsa out and also to another app dl-fldigi.
It's working (off a fashion) using this hacky script
https://gist.github.com/jrobinson-uk/123daebd8ff58d636ba02da9dfd7f3e1 which
basically
starts the jack server
starts the 3 apps to link (mplayer --> alsa_out --> dl-fldigi)
links mplayer to alsa then also to dl-fldigi
I have 2 questions:
Some of the apps either crash occasionally (dl-fldigi) or their is a case
for restarting them (mplayer), at the moment I have to recreate the
connections each time an app closes. Is it possible to create the
connections first and have them persist, then connect the apps when they are
(re)started?
Secondly I have some audio issues, there are fractional pauses every so
often which make the audio had to decode, is there anything about piping
through jack that could cause this, on something which might mitigate it?
James
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26 Jul
26 Jul
2:53 p.m.
On Tue, Jul 26, 2016 at 11:16:18AM -0700, james-rpf wrote:
Hi,
I'm trying to get receive audio data from a USB software defined radio and
pipe it through jack to alsa out and also to another app dl-fldigi.
It's working (off a fashion) using this hacky script
https://gist.github.com/jrobinson-uk/123daebd8ff58d636ba02da9dfd7f3e1 which
basically
starts the jack server
starts the 3 apps to link (mplayer --> alsa_out --> dl-fldigi)
links mplayer to alsa then also to dl-fldigi
I have 2 questions:
Maybe you could explain what exactly you are trying to do...
I don't see the relation of mplayer with software defined radio,
nor why you'd use alsa_out...
Ciao,
--
FA
A world of exhaustive, reliable metadata would be an utopia.
It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)
3:30 p.m.
On Tue, July 26, 2016 1:16 pm, james-rpf wrote:
I'm trying to get receive audio data from a USB
software defined radio and
pipe it through jack to alsa out and also to another app dl-fldigi.
Are you using alsa_out because you need sample rate conversion? Why are
you not sending to the ALSA hardware device directly? Or do you mean you
connect to the output of your ALSA hardware, and not that you are using
the "alsa_out" resampling jack client?
Secondly I have some audio issues, there are
fractional pauses every so
often which make the audio had to decode, is there anything about piping
through jack that could cause this, on something which might mitigate it?
Look for underrun/overrun messages in jack (probably displayed as "xrun"
messages).
If you have xrun problems you can try increasing the number of frames per
period, and when using USB the recommendation is typically to use 3
periods per buffer (-p and -n arguments to jackd respectively).
If all else fails you can switch to a kernel with real-time extensions
(-RT patch series). I don't think you mentioned what kernel you are
using, before switching completely to the -RT variant you could also try a
kernel compiled with the low latency configuration (shown as voluntary
preemption in the kernel config options, will show as PREEMPT in the
kernel config file). Often a PREEMPT kernel with large number of frames
per period will work well enough that you don't need the PREEMPT-RT kernel
variant.
--
Chris Caudle
29 Jul
29 Jul
3 p.m.
On Tue, Jul 26, 2016 at 11:16:18AM -0700, james-rpf wrote:
Hi,
I'm trying to get receive audio data from a USB software defined radio and
pipe it through jack to alsa out and also to another app dl-fldigi.
It's working (off a fashion) using this hacky script
https://gist.github.com/jrobinson-uk/123daebd8ff58d636ba02da9dfd7f3e1 which
basically
starts the jack server
starts the 3 apps to link (mplayer --> alsa_out --> dl-fldigi)
links mplayer to alsa then also to dl-fldigi
I have 2 questions:
Some of the apps either crash occasionally (dl-fldigi) or their is a case
for restarting them (mplayer), at the moment I have to recreate the
connections each time an app closes. Is it possible to create the
connections first and have them persist, then connect the apps when they are
(re)started?
You could set up the connections once with either qjackctl or
aj-snapshot (command-line app), and have them automatically be
recreated. In qjackctl you would create a patch, and load it.
With aj-snapshot, you would have to run it in daemon mode.
lieven
2821
days inactive
2824
days old
jackaudio@lists.linuxaudio.org
3 comments
4 participants
participants (4)
-
Chris Caudle -
Fons Adriaensen -
james-rpf -
Lieven Moors