write(2) lc_r problem
Stefan Ehmann
shoesoft at gmx.net
Sat Jan 24 11:48:15 PST 2004
On Sat, 2004-01-24 at 20:15, Mathew Kanner wrote:
> On Jan 24, Stefan Ehmann wrote:
> > I'm trying to write a small sound application and run across a problem
> > on CURRENT.
> >
> > It's very basic at the moment. It simply reads pcm data from a file and
> > uses write(2) on /dev/dsp.
> >
> > But as soon as I link the program with -lc_r there's always about 1
> > second delay before a write call - which makes it pretty unusable for
> > playing sound.
> >
> > It should be easy reproducable if you link audio/waveplay with -lc_r.
> >
> > This doesn't happen in either FreeBSD 4.9, Knoppix or CURRENT if linked
> > with -lkse or -lthr.
> >
> > Am I'm missing something basic when using write together with lc_r or
> > ist this a bug in CURRENT?
>
> There is definetly a bug with the sound code when using vchans
> and select. Make sure that (using sysctl)
>
> hw.snd.maxautovchans=0
> hw.snd.pcmX.vchans=0
You're right, that fixed it. That's also the reason why it worked on
stable (vchans was disabled there).
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