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List:       kde-multimedia
Subject:    Re: noatun - playing too slowly
From:       Stefan Westerfeld <stefan () space ! twc ! de>
Date:       2001-02-22 0:37:48
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   Hi!

On Mon, Feb 19, 2001 at 11:34:04AM -0500, Jeff Tranter wrote:
> I've noticed a problem with noatun on my machine. When playing an
> MP3 file it plays at about half normal speed. The pitch of the song is
> correct, it just plays slowly. I can play MP3s fine with xmms using the
> aRts plug-in and kaiman worked okay (when it was still around).
> This is a fast machine (600MHz Pentium III) and artsd and notun are
> talking only a small amount of CPU time. I don't see any unusal errors
> from notatun or artsd.
> 
> If I go into the Effects dialog and enable the FreeVerb effect, the problem
> seems to goes away, even if I remove the effect again.  It also goes
> away if I enable and then diable FreeVerb from artscontrol. It then seems
> okay until the next time the sound server is started up.
> 
> Any hints as to where to start to debug this? I am using a current CVS version.

The mpeglib_artsplug code (which acts as "gateway" between aRts and mpeglib)
resamples data that the thread has decoded and inserts it into the aRts stream
inside it's calculateBlock() implementation. It inserts zero samples whenever
the thread hasn't provided enough decompressed data. So my guess is that this
zero insertion code is triggered and causes the problem here.

To start debugging, it might be a good idea to have a look at

int DecoderBaseObject_impl::fillArts(unsigned long samples,
                     float* left , float* right)

(in kdemultimedia/mpeglib_artsplug/decoderBaseObject_impl.cpp) and insert
a few debugging printfs there. Another thing you can try is playing around
with the fragment size (start artsd manually), to see if that has any effect
on the bug.

   Cu... Stefan
-- 
  -* Stefan Westerfeld, stefan@space.twc.de (PGP!), Hamburg/Germany
     KDE Developer, project infos at http://space.twc.de/~stefan/kde *-         
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