Openmoko Bug #1614: Mediplayer isn't able to play Ogg/Vorbis files

Russell Sears sears at
Wed Jul 16 23:54:41 CEST 2008

I've been looking into this a bit.  Some ogg files are playable, 
depending on encoding.  The problem is that the hardware is too slow to 
play ogg files back with the default configuration.  It doesn't have a 
floating point unit, so things get tricky.

It sounds like pulseaudio shouldn't be using much CPU time at all, at 
least according to this thread (which referrs to a different device / os):

We probably should figure out what pulseaudio is actually doing, then 
look into making it not do that.

I've been trying to figure out where the gst-plugin-vorbisi file's 
source code lives for further debugging, but I've been busy and it's 
been slow going.  I've managed to find the source code for 
gst-plugin-vorbis, but that one uses floating point math, and is slower 
than the one shipped on the phone.

Beyond fixing the pulseaudio overhead by getting it to stop doing 
software mixing / resampling / ???, there are some other things that 
could help:

- tremolo, which is an ARM specific version of tremor.  Tremor is the 
integer math ogg implementation shipped by default

- _LOW_ACCURACY_ mode, which seems to corrupt a few lsbs of the signal, 
but saves CPU time.

- Double checking compilation options.


Openmoko Public Trac wrote:
> #1614: Mediplayer isn't able to play Ogg/Vorbis files
> ---------------------+------------------------------------------------------
>  Reporter:  HdR      |       Owner:  openmoko-devel      
>      Type:  defect   |      Status:  new                 
>  Priority:  high     |   Milestone:                      
> Component:  unknown  |     Version:  2007.2              
>  Severity:  normal   |    Keywords:  openmoko-mediaplayer
>  Blocking:           |   Blockedby:                      
> ---------------------+------------------------------------------------------
>  As the title says, the openmoko-mediaplayer isn't able to play Ogg/Vorbis
>  files.
>  The files are added corretly to the play list, but if you press play, the
>  mediaplayer only plays a short extract of the track (about the first
>  second, maybe).
>  ogg123 and mplayer are able to play Ogg/vorbis files (with about 50% CPU
>  usage), if pulseaudio isn't running.

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