Crackles and xrun with latency 256 and SB Live

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Crackles and xrun with latency 256 and SB Live

Peder Hedlund
After some searching I found the jam_ard-master.tar.gz file mentioned on
the Jamin tutorial page (I had to search the mail list archive to find
it, note to any jamin developer reading this: make a link!) and thought
I'd test it. I got the latest ardour, jamin and jack, got the latest
realtime patch from mingo (realtime-preempt-2.6.12-rc5-V0.7.47-16), the
realtime lsm module and schedtool , cranked jack latency down to 256 and
fired the whole shebang up.

It plays fine the first couple of minutes but somewhere between 02:00 and
03:30 I always get lots of crackle (sometimes it sounds almost
ringmodulated) and when that stops I get an xrun. Then it plays fine
for a while more and then repeats itself (crackle and an xrun).

I have an AMD1400+, 512MB RAM and a SB LIVE! so it's perfectly possible I
can't use that low a latency given the specs, but I'd be interested to
hear any suggestions people might have.

 - Peder




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Re: Crackles and xrun with latency 256 and SB Live

Alexandre Prokoudine
On 6/7/05, Peder Hedlund <[hidden email]> wrote:
> After some searching I found the jam_ard-master.tar.gz file mentioned on
> the Jamin tutorial page (I had to search the mail list archive to find
> it, note to any jamin developer reading this: make a link!)

My fault. I never have enough time to read through the whole docs of
project administration at SourceForge.net. Will try to upload files
this week.

Alexandre


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Re: Crackles and xrun with latency 256 and SB Live

R Parker
In reply to this post by Peder Hedlund
Hi Peder,

> After some searching I found the
> jam_ard-master.tar.gz file mentioned on
> the Jamin tutorial page (I had to search the mail
> list archive to find
> it, note to any jamin developer reading this: make a
> link!) and thought
> I'd test it. I got the latest ardour, jamin and
> jack, got the latest
> realtime patch from mingo
> (realtime-preempt-2.6.12-rc5-V0.7.47-16), the
> realtime lsm module and schedtool , cranked jack
> latency down to 256 and
> fired the whole shebang up.
>
> It plays fine the first couple of minutes but
> somewhere between 02:00 and
> 03:30 I always get lots of crackle (sometimes it
> sounds almost
> ringmodulated) and when that stops I get an xrun.
> Then it plays fine
> for a while more and then repeats itself (crackle
> and an xrun).

Ah, the dark art of system tuning. There's some good
hints at Planet CCRMA
(http://ccrma.stanford.edu/planetccrma/software/tunesystem.html).

Maybe that will give you a place to start.

> I have an AMD1400+, 512MB RAM and a SB LIVE! so it's
> perfectly possible I
> can't use that low a latency given the specs, but
> I'd be interested to
> hear any suggestions people might have.

My system is capable of 256 but I record and mix at
1024. I have no good reason for using a lower latency.
Let me know if you think the tutorial is worth the
effort. If you have suggestions for improving it I'm
all ears.

ron

>  - Peder
>
>
>
>
>
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> little guy.  
> Play to win an NEC 61" plasma display:
> http://www.necitguy.com/?r=20
> _______________________________________________
> Jackit-devel mailing list
> [hidden email]
>
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Re: Crackles and xrun with latency 256 and SB Live

Lee Revell
In reply to this post by Peder Hedlund
On Tue, 2005-06-07 at 16:12 +0200, Peder Hedlund wrote:
> It plays fine the first couple of minutes but somewhere between 02:00
> and
> 03:30 I always get lots of crackle (sometimes it sounds almost
> ringmodulated) and when that stops I get an xrun. Then it plays fine
> for a while more and then repeats itself (crackle and an xrun).
>
> I have an AMD1400+, 512MB RAM and a SB LIVE!

Running at 44100Hz, huh?  That was a bug in JACK, that has been fixed
for a month or so.  Get a newer JACK from CVS.

I highly recommend running at 48000Hz with the EMU10K* based cards.
With ALSA 1.0.9 or newer, this gives you 16 inputs and 16 outputs, with
each physical input/output corresponding to a separate JACK port, and
latencies as low as 32 frames.  Using any other sample rate restricts
you to 2in, 2out at once.

If you're working with 44100HZ source material, you will get better
results running JACK at 48000HZ and doing the resampling in your app.
The hardware SRC on those chips is not nearly as good as a high quality
software resampler; it's intended for games and system sounds, not music
making.

See Documentation/emu10k1-jack.txt.

Lee




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Re: Crackles and xrun with latency 256 and SB Live

Peder Hedlund
Den Thu, 09 Jun 2005 11:53:50 -0400 skrev Lee Revell:

> Running at 44100Hz, huh?  That was a bug in JACK, that has been fixed
> for a month or so.  Get a newer JACK from CVS.

 In that case, it's still there. I'm running JACK CVS from June 3.

 With that said, I found out yesterday that if I run JACK at 48kHz it
 works fine. I can even go as low as 128 frames/period w/o any xrun.

 From what I've read elsewhere Creative cards (perhaps excluding
 the latest Audigy cards) resample everything internally to 48kHz so I
 guess that for some reason that couldn't keep up, causing the xrun.

 Thanx guys,

  - Peder



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