[PD] first trial,. but no sound

Kaj Ailomaa kaj.ailomaa at mousike.me
Wed Jul 4 13:28:24 CEST 2012

On Wed, 2012-07-04 at 08:20 +0200, Stefan Thomas wrote:
> Dear Iain,
> I did as You suggested, the problem remains the same.
> One problem might be:
> When I reinstall PD some of the other PD-related packages will be
> reinstalled to.
> But I've read in the meantime, that my problem could be a bug, related
> to my version of PD.
> It seems to be the same problem like the one, I have read on this
> site:
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=645041

Yep. It seems to be a bug with that release. 

I've added an example as an attachment. Should be enough to check if
everything works.

Alsa works for me, but it doesn't work well at lower latencies. Jack is
preferred for that. 
Only, to get lower latencies with jack, you'll need to install
linux-lowlatency (low latency capable linux kernel) and set up realtime
privilege (all this is done if you installed Ubuntu Studio).

To set up realtime privilege, you'll need to do a few things.

First, install linux-lowlatency: sudo apt-get install linux-lowlatency

Second, you need to answer yes when asked about this when installing
jack. If unsure, see that the file /etc/security/limits.d/audio.conf is
not named /etc/security/limits.d/audio.conf.disabled. To rename it, do
this in a terminal:
sudo mv /etc/security/limits.d/audio.conf.disabled
Inside that file, you need to have these two lines uncommented (they
should be by default):

@audio   -  rtprio     95
@audio   -  memlock    unlimited

If the file doesn't exist, just create it: sudo nano
..and add the two lines above.

The third thing to do is to add yourself to audio group: sudo usermod -a
-G audio $USER

Then, reboot.

Latency is adjusted separately for both jack and pd. I believe jack
handles audio latency when used with pd, while pd handles its' internal
data latency.
Good latency for me is 64 frames/period in qjackctl settings, and around
5-10 ms in pd jack settings.

  kaj.ailomaa at mousike.me
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