From alsa-user-owner@alsa.jcu.cz  Fri Dec 18 21:18:25 1998
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Date: Fri, 18 Dec 1998 14:16:30 -0600
To: alsa-user@alsa.jcu.cz
Subject: Re: interference from video
Message-ID: <19981218141630.B255@storms-177-146.res.iastate.edu>
References: <9812189140.AA914004125@creyfs.be> <Pine.LNX.3.96.981218191315.6015I-100000@entry.jcu.cz>
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In-Reply-To: <Pine.LNX.3.96.981218191315.6015I-100000@entry.jcu.cz>; from Jaroslav Kysela on Fri, Dec 18, 1998 at 07:39:58PM +0100
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On Fri, Dec 18, 1998 at 07:39:58PM +0100, Jaroslav Kysela wrote:
> On Fri, 18 Dec 1998 ghp@creyfs.be wrote:
> 
> > 
> > Hello,
> > 
> > When using alsa, I have a lot of noise that comes from the display.  Moving the
> > mouse or a window, or a program displaying rapidly changing information (like
> > timidity's time bar), causes this noise or interference.
> 
> I'm not sure if we can improve driver to remove some noises. Most of
> noises are analog type. I should say, that only digital output from
> soundcard (which bypass analog path) can solve all computer interferences.
> 
> I have connected digital output from Turtle Beach Malibu (CS4237B)
> soundcard to Sony STR-DB925 receiver and I should confirm that all
> computer noises and start/end clicks disappear. Thus problem should be
> somewhere in analog mixer and amplifier.

  I think that the problem here is different than the analog interference
caused by electromagnetic interference witht the signal inside the case... I
had a similar problem, such as resizing or zooming windows, moving things
around the desktop.  I think that it may be because some interupt has
priority, such as the video, but what I did to solve it (or mabye what
caused the problem, was this line in my XF86Config file...

    #Option "pci_retry"    # faster, but problematic for ISA DMA

I disabled the pci_retry and the sounds when moving windows disapeared. 
Actually, to be more discriptive, the "sounds" was not actually sound, but
the sound being interupted, and so when I move a window a lot durring
playback (such as x11amp) It acted like pitch bending, as the playback would
slow down.

  Hope this helps.

-- 
Jacob Jaeggli
jjaeggli@iastate.edu

