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

[From: Simon Pickering]

> > 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. 

Cheers,


Simon