[linux-audio-user] Re: [Jackit-devel] [Fwd: Re: Linux audio latency]

Lee Revell rlrevell at joe-job.com
Sat Oct 2 18:26:10 EDT 2004


On Sat, 2004-10-02 at 18:03, John Hedditch wrote:
> > On Sat, 2004-10-02 at 17:31, Florian Schmidt wrote:
> > > Also maybe the alsa drivers themselfes might be problematic/buggy. If
> > > the above minimal alsa app still produces xruns, then either alsa lib or
> > > the drivers themselfes are to blame [probably].
> > > 
> > > Of course such a test is not a proof but might give important clues.
> 
> How about the following?
> arecord -t raw -r96000 -fU24_LE -c2 --period-size=64 --buffer-size=128 fish
> 
> This work just fine (no xruns). 
> 
> If we tried to drop down to 32 frames per period it (unsurprisingly) 
> breaks, however, and we get
> the following:
> arecord -t raw -r96000 -fU24_LE -c2 --period-size=32 --buffer-size=64 fish
> Recording raw data 'fish' : Unsigned 24 bit Little Endian, Rate 96000 Hz, Stereo
> overrun!!! (at least 0.087 ms long)
> overrun!!! (at least 0.053 ms long)
> overrun!!! (at least 0.152 ms long)
> overrun!!! (at least 0.055 ms long)
> overrun!!! (at least 0.055 ms long)
> overrun!!! (at least 0.054 ms long)
> overrun!!! (at least 0.064 ms long)
> overrun!!! (at least 0.070 ms long)
> overrun!!! (at least 0.166 ms long)
> overrun!!! (at least 0.175 ms long)
> overrun!!! (at least 0.165 ms long)
> overrun!!! (at least 0.175 ms long)
> 
> Anyway, this tends to support the jack client / jackd hypothesis, yes?
> 

Right, this is exactly the expected behavior with the VP kernel.  64
frames at 96kHz (or 32 at 48kHz) is about the lower limit of PC
hardware, I would expect 32 @ 96 to break.

Try to isolate the jack clients that don't work...

Lee




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