Ogg vorbis performance.
sears at cs.berkeley.edu
Sun Jul 13 09:34:48 CEST 2008
Sören Apel wrote:
> On Sat, 2008-07-12 at 14:27 -0700, Russell Sears wrote:
>> I've noticed that my freerunner is *almost* fast enough to play my ogg
>> vorbis files; running a second app, or even gpsd causes the media player
>> to skip, then to go silent.
>> What's been done to get ogg vorbis to perform well so far? ogg123,
>> oggdec seem to be able to decode in roughly 2/3's realtime, which is
>> similar to the CPU usage of openmoko-mediaplayer.
> If I remember correctly it was a problem with the sample rate/sample
> meaning that resampling had to take place - which eats CPU like candy.
Ouch. What sample rate does the hardware provide, and does pulseaudio
or gstreamer do the resampling? Also, decoding to /dev/null is slow...
That shouldn't resample should it?
I've noticed that things I've encoded more recently seem to be less
likely to play (perhaps I changed an encoding setting at some point...),
but that it varies from track to track... I'll time some files, and see
if I can find a pattern.
>> I noticed that gstreamer is using libvorbisi (tremor) since there is no
>> floating point unit. It looks like there are three ways to make it go
>> - Tremolo, which is ARM specific, and claims 15-20% better performance
>> - _LOW_ACCURACY_ mode
>> - The "low-mem" branch of tremor
>> Which of these have been tried so far?
> None, as I didn't find the time unfortunately.
> You're more than welcome to try these :)
More information about the openmoko-devel