[maemo-developers] [maemo-developers] Ogg Vorbis and the N800

From: Simon Pickering S.G.Pickering at bath.ac.uk
Date: Mon Jan 29 12:40:21 EET 2007

> > Conclusion:
> > It works but the cpu load is high. Vorbis decoding takes almost 80% 
> > cpu. I also tried MPlayer 1.0rc1-maemo.8 which has the integer based 
> > Tremor decoder codec [4] nicely integrated. Tremor needs around 12% 
> > cpu for the same ogg file. (That is an expected scale up from the 770 
> > experience - tremor takes around 20% cpu on the 770 - due to the 
> > faster cpu of the n800)
> >
> > It exceeds my skills to analyze this much further. However it seems 
> > that the vorbis decoder is not vfp optimized ;-) [yet?].
> Did you specify any compiler flags or just compile as-is?
> I'm not 100% sure but I've let myself belive (based on 
> comments on the IRC channel) that it won't compile with vfp 
> unless you specify "-mfpu=vfp -mfloat-abi=softfp" for the 
> compiler. Also based on the chatting on #maemo, 
> "-mcpu=arm1136j-s" might be worth it.

Those were my comments and yes, simply specifying "-mfpu=vfp" produced
soft-float code rather than the expected hard-float.

I guess I should also take this opportunity to note that libm on the N800
appears to not use hard-float either (thanks jacques on irc for bringing
this up). Or at least it's very very slow. This will cause some significant
slowdown on the variety of functions it provides. 



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