[vorbis] Strange dropouts

[Tomi Jylhä-Ollila]

On Fri, 2002-08-02 at 04:24, John Morton wrote:
> On Fri, 02 Aug 2002 00:25, Tomi Jylhä-Ollila wrote:
> > First of all, *thanks* to all the developers for their hard work on Ogg
> > Vorbis. It's greatly appreciated.
> >
> > I'm having a problem with encoding in Debian GNU/Linux 3.0. The oggs
> > contain occasional dropouts and "blips" here and there.
> >
> > Example files:
> >
> > Original (~7 MB):
> > http://personal.inet.fi/musiikki/nebularia/test/t2title.flac
> >
> > Ogg Vorbis file (~800 KB):
> > http://personal.inet.fi/musiikki/nebularia/test/t2title.ogg
> >
> > Decoded back from Ogg Vorbis (~6.5 MB):
> > http://personal.inet.fi/musiikki/nebularia/test/t2title-decoded.flac
> >
> > I've tried to compile all the ogg and vorbis-related stuff with gcc
> > 2.95, 3.0 and 3.1 and also tested the official deb files but none of
> > them fixed the problem for me. These errors don't reproduce exactly the
> > same way if I re-encode the ogg file but _do_ sound always the same when
> > playing it so the errors are probably in the file.
> >
> > Windows binaries, however, work fine.
> >
> > Does anyone know what the problem is? TIA for any help.
> 
> I downloaded the ogg and played it without any noticable problems. You either 
> have some sort of decoder problem, or (more likely) your system latency is 
> high enough to prevent the decoder from keeping the audio buffer full. 

Hmm. I'd still say there's something wrong with the file. The most
audible errors are in the very beginning and after 30 seconds or so.
Here's a screenshot showing one of the errors very clearly (at ~30-35
seconds, very audible and visible):
http://personal.inet.fi/musiikki/nebularia/test/error.jpg
It shows clearly the spot on the right where most frequencies are
missing... Try it with headphones. It's even more audible that way.

If the ogg really is OK (which I would find unlikely), maybe you could
try the t2title-decoded.flac. At least that one demonstrates the
problems.

Maybe I should also point out that *only* the oggs I've encoded in
Debian have these problems. The oggs I encoded in Windows work fine in
Debian. Also, the oggs from the test page in vorbis.com play perfectly.

> I suggest you use xmms and the crossfade plugin. In the misc options for the 
> crossfader, enable 'Show Buffer Monitor', then play your oggs and watch the 
> monitor to see how fast the decoder is fulling the buffers, and what sort of 
> activity is slowing it down.

I tried it and everything seemed to be working fine buffer-wise. And the
errors I'm hearing don't sound like buffer underruns to me.

Cheers,

 - Tomi Jylhä-Ollila

<p><p><p><p><p>--- >8 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'vorbis-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.