[RDD] Real time Kernel

Dan Mills dmills at exponent.myzen.co.uk
Tue Aug 12 13:42:01 EDT 2008


On Tue, 2008-08-12 at 11:58 -0400, drew Roberts wrote:

> 
> I seem to remember reading on list before that a real time kernel would not be 
> necessary for proper rivendell operations. I could be mistaken though and am 
> interested to see what responses this post generates. Whatever the outcome, I 
> think we might want to make this answer permanent on the wiki.

Indeed, RT does not hurt, but it should not really be necessary (Unless
using jack at low period values, this is more of a jack issue then an RD
one).

Stock Rivendell runs (for Alsa) at 1024 frames per period, 2 periods by
default, which is hardly low latency (And really doesn't need to be any
lower), a stock kernel should do fine. 

One thing that might be biting you is that some common on board sound
chipsets do not work properly with two periods (some of the Intel HDA
parts spring to mind), and need 3 periods for correct operation.... This
manifests itself as severe stuttering (often without a corresponding
xrun count in jackd).
The fix is to add something like:

[Alsa]
; ALSA Parameters
; (It should seldom be necessary to tweak these)
PeriodQuantity=3
PeriodSize=1024

To /etc/rd.conf (Then restart the daemons).

This is not a problem when using a sane audio device. 

HTH.
Regards, Dan.
 





> Have you made any now and next progress?
> >
> > Tim Camp
> > Director of Operations/Programming
> > Chief Engineer
> > WZEW-FM WNSP-FM
> > Mobile, Al.
> 
> all the best,
> 
> drew
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> Rivendell-dev at techweb.rfa.org
> http://techweb.rfa.org/mailman/listinfo/rivendell-dev



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