Re: real-time threaded IO with low latency (audio)

Gerhard Mack (gmack@imag.net)
Sat, 24 Jul 1999 17:39:47 +0000 ( )


On Sat, 24 Jul 1999, Daniel Kobras wrote:

> On Sat, 24 Jul 1999, Gerhard Mack wrote:
>
> > On Fri, 23 Jul 1999, Ingo Molnar wrote:
> >
> > > the whole 'why sound skips' problem i think lacks one major necessery
> > > component: information. Nobody really ever analyzed what the problem
> > > really is/was. I do have a awe64 soundcard (which i almost never use), if
> > > you (or anyone else) could point to a method to make sound-playback
> > > produce bad quality, i'd be happy to analyze the problem. Is running
> > > mpg123 enough to see the problem? What should i do to make sound skip?
>
> > Mpg123 will skip as the disk usage gets heavy.
> >
> > Somewhere between 2.2.8 and 2.3.4 something drastically reduced the sound
> > dropouts on my system. I used to be able to make the sound skip even with
> > "mpg123 -b 1024" but that is no longer the case.
>
> In my experience setting the buffer size to a higher value won't do you a
> blind good as the problem is not input bound but rather on the output
> side. Heavy disk i/o locks out mpg123's buffer process, therefore
> audio_play_samples() doesn't get run often enough. So to me it looks like
> mingos additional schedule()s are certainly in the right ballpark. For a
> simple test case on sound skippishness, disable DMA on an IDE disk and run
> a find on it while playing sound. [Or be the proud owner of any IDE

Without the buffer has sound blockouts, with sound buffer it doesn't I've
not varried the size I just use 1024 because that's what somone suggested
on this list a few months ago.

Gerhard

--
gmack@imag.net

As a computer I find your faith in technology amusing.

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