[PD] Which Linux distribution are you using?

Raphael Raccuia rafael.raccuia at blindekinder.com
Wed Nov 17 10:51:25 CET 2010



Le 17. 11. 10 03:36, Martin Schied a écrit :
> On 15.11.2010 23:06, Raphael Raccuia wrote:
>>
>>
>> Le 15. 11. 10 22:21, Pierre Massat a écrit :
>>> Hi,
>>> I have installed Ubuntu 10.04 LTS, plus some ubuntu studio stuff 
>>> (the audio packages and the plugins). I also tried the rt-kernel. It 
>>> didn't work.
>>> But i am amazed, blown away, baffled, etc. Because the generic 
>>> kernel does have some crazy rt capabilities indeed. I guess the 
>>> ubuntu studio packages must have created the audio group and jack 
>>> must have written the proper things in the limit file, but still, it 
>>> works surprisingly well. Jack can run in rt with a latency as low 4 
>>> ms without any xruns, although it crashes.It works just fine at 5.33 
>>> ms. Even pd itself work with an extremely low latency (I'd say below 
>>> 7 ms), I'm assuming that's because it was configured to run in rt 
>>> during the install.
>>> I don't even know if i need JACK anymore.
>> jack don't add latency, and it's a powerfull sound server... you can 
>> connect pd to the outputs of your sound device and/or other 
>> sound/midi softwares, then you can save a patchbay to recover your 
>> patch... it's one of the most interesting stuffs on linux.
>>
> it does add latency in most cases. you specify the amount of latency 
> by using different period sizes and numbers of periods settings. But 
> you can use very small buffers on some systems with good audio 
> hardware, so they have the same size you would use inside pd in 
> standalone (64samples). In this case you will not have more latency 
> using jack than using pd standalone. (I'm also only 99.9% sure about 
> this, beware.).
 From jack-audio.org


    "Doesn't use JACK add latency?

There is /NO/ extra latency caused by using JACK for audio input and 
output. When we say none, we mean absolutely zero. The only impact of 
using JACK is a slight increase in the amount of work done by the CPU to 
process a given chunk of audio, which means that in theory you could not 
get 100% of the processing power that you might get it if your 
application(s) used ALSA or CoreAudio directly. However, given that the 
difference is less than 1%, and that your system will be unstable before 
you get close to 80% of the theoretical processing power, the effect is 
completely disregardable."

but of course, if you just run pd, you don't need it and you can set 
latency into pd, I forgot that. I mostly interface pd with other soft ( 
ardour or any recorder, midi sequencer, some plugin via jack-rack or 
calf etc...), and I plug midi controllers, but you can do it in qjackctl 
without running jack (alsa tab in connection window)...

>
> Practically speaking - on systems I used until now I could always 
> achieve lower buffer sizes using pd standalone and thus get lower 
> round trip delays too.
>>> I couldn't tell by ear which config was faster, Pd alone or Pd plus 
>>> JACK.
>> maybe I'm wrong, but I thing only jack can provide rt...
> you can run pd with the -rt flag, without jack. fo me it has proven to 
> be far more stable at the lowest possible latencies than using jack. 
> but this depends on your setup too. I don't use jack when I don't need it.
>
> Martin
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.puredata.info/pipermail/pd-list/attachments/20101117/d3ecc77f/attachment-0001.htm>


More information about the Pd-list mailing list