Ogg vorbis performance.

Sören Apel abraxa at dar-clan.de
Thu Jul 17 18:07:42 CEST 2008

On Thu, 2008-07-17 at 08:27 -0700, Russell Sears wrote:
> Russell Sears wrote:
> I uploaded a fix to the bug tracker.  It bypasses PulseAudio and uses 
> ALSA.  Any idea why that helps?  In principle, ALSA and PulseAudio 
> should have to perform the same computations to play the sound back 
> (alsa contains a software resampler...)  I haven't been able to find any 
> obviously mistakes in the configuration files.

It's been a while but from what I remember, the PulseAudio plugin puts
contraints on the data stream that are incompatible with the libtremor
format, which in turn enforces sample conversion to take place. The ALSA
plugin may not have these constraints.
Again, that's from memory so I'm not 100% sure on what the cause was

> Also, are there any bad implications to bypassing pulseaudio?  I haven't 
> noticed any.  I'd like to get ogg vorbis (and anything else that outputs 
> 16bit/44.1kHz) fixed in the official image...

PulseAudio is great and would allow for great things - e.g. seamless
audio stream moving (play files on Neo, have them come out of your
desktop soundcard). Aside from that, PulseAudio also allows for
simultaneous usage of the soundcard, which ALSA still has issues with.
Dmix, esd & friends pale in comparison to PulseAudio as well.

Of course any intermediate layer will affect performance and even more
so as tons of applications still try to access ALSA directly - which
would only work with a plugin on top of PulseAudio to allow this, or
ugly workarounds like pasuspend.

mickey told me that FSO doesn't use PulseAudio anymore. You might want
to see how they solved the ALSA problem there or whether they just left
PulseAudio out and ignore the problem of having several apps trying to
access ALSA at the same time.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: This is a digitally signed message part
Url : http://lists.openmoko.org/pipermail/devel/attachments/20080717/c6c926bb/attachment.pgp 

More information about the devel mailing list