[PD] Latency under Linux/Jack (again...)

Raphael Raccuia rafael.raccuia at blindekinder.com
Tue Oct 12 22:14:15 CEST 2010


tried with just one security config, no changes...

Lorenzo a écrit :
>
>> -RME Multiface I /HDSP expresscard
>>    
> So this (not the pcmcia) works on linux? That's interesting news.
OT: it should... I asked on many forums to be sure it does, and people 
said me "it's basically the same as pcmcia"... but I have a lot of 
trouble: freeze on boot 9/10... but 1/10, when it works it works pretty 
good! It could be a hardware issue (my computer). I'm talking with a RME 
technician to fix it, or almost know where the problem comes from...
>
> I also do get some xruns now and then when moving around gui object 
> (like selecting a whole lot of objects and moving them around) even 
> with rt kernel, pd run with -rt etc etc...
> Otherwise it is usually *quite* stable.
>
> Lorenzo
>> Of course jack run with -R. I repeat I don't have any problem to run
>> application with really good latency: yesterday, I forgot to increase
>> buffer as I worked on a 96000Hz Ardour session... I noticed I was
>> working at 5ms I/O after one hour recording and playing a lot of tracks,
>> and no xrun, no problems...
>> I also think it's not a good Idea to run pd as root... and I suppose
>> other application won't connect to jack if I run it as root also.
>>
>> I noticed I had two times the @audio config (limits.conf, audio.conf).
>> You'll say: "better twice than nothing"... But maybe it generates a
>> conflict... I try
>>
>> Le mardi 12 octobre 2010 à 11:50 -0300, Bernardo Barros a écrit :
>>   
>>> Don't run programs as root, your system will be as insecure as a 
>>> windows box...
>>> Just allow rt privileges to the audio group, and add yourself to 
>>> this group.
>>> Then start jack with rt privileges. All software linked to Jack will
>>> run with -rt.
>>>
>>> from http://jackaudio.org/faq
>>>
>>> JACK requires real-time scheduling privileges for reliable,
>>> dropout-free operation. The server requests these privileges when
>>> running with the -R option.
>>>
>>> Most recent distributions use PAM to manage the permissions of users
>>> on a relatively granular level. If the file /etc/security/limits.conf
>>> exists on your system, it is using PAM. In order to configure PAM such
>>> that normal users can run jackd with realtime privileges make sure the
>>> following lines exist:
>>> @audio   -  rtprio     99
>>> @audio   -  memlock    unlimited
>>>
>>>
>>> 2010/10/12 Pedro Lopes<pedro.lopes at ist.utl.pt>:
>>>     
>>>> If you start pd in sudo, you have to connect to jack in sudo mode. 
>>>> Thus
>>>> start jack in sudo (or gksudo for qjackctl).
>>>> I advise to use an rt kernel too. See documentation of Ubuntu Studio.
>>>>
>>>> On Tue, Oct 12, 2010 at 3:27 PM, Raphael Raccuia
>>>> <rafael.raccuia at blindekinder.com>  wrote:
>>>>       
>>>>> Hi list,
>>>>> I tested Pd rt as I need low latency for a performance next week...
>>>>> It seems -rt flag doesn't have any effect. I measured Pd latency with
>>>>> jdelay, and always get 640 (@48000), so about 13ms (pd only)... 
>>>>> lower I
>>>>> set buffer in jack (no less than 256), more DIO errors I get... and
>>>>> there are a lot! This setting works great with many application
>>>>> (Ardour...), with about 10ms (~15 really). So I would have ~25ms, 
>>>>> which
>>>>> is acceptable, but too many DIO errors!
>>>>>
>>>>> -what is -defeatrt setting? (I tried 0 and 1, no change)
>>>>> -why is -rt flag without effect?
>>>>> -tried nosleep, no change...
>>>>>
>>>>> I also tried to start pd in root (sudo)...
>>>>>
>>>>> It says:
>>>>> priority 8 scheduling enabled.
>>>>> priority 6 scheduling enabled.
>>>>> (which I normally don't have)
>>>>>
>>>>> but unfortunately can't connect to jack (state 17)
>>>>>
>>>>> thank's for your help
>>>>>
>>>>>
>>>>> _______________________________________________
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>>>>>          
>>>>
>>>>
>>>> -- 
>>>> Pedro Lopes (ongoing MSc)
>>>> contact: pedro.lopes at ist.utl.pt
>>>> website: http://web.ist.utl.pt/Pedro.Lopes
>>>>
>>>> _______________________________________________
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>>>>
>>>>
>>>>        
>>
>>
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>
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