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

[From: Kalle Vahlman]

2007/1/30, Krischan Keitsch <krishan.keitsch at alumni.tu-berlin.de>:
> Am Montag, 29. Januar 2007 09:08 schrieb Kalle Vahlman:
> > 2007/1/29, Krischan Keitsch <krischan.keitsch at alumni.tu-berlin.de>:
> > > Hi
> > >
> > > as far as I can tell the n800 with the OMAP2420 processor has a vfp
> > > (vector floating point unit; see [1] ) Based on this I wanted to find out
> > > if vorbis could take advantage of this unit by default.
> > >
> > > To make it short: Yes it works - BUT it is just painful!
> >
> > [...]
> >
> > > 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.
>
> I tried again with the flags
> mfpu=vfp mfp=vfp mcpu=arm1136j-s
> (mfloat-abi=... didn't work)
>
> (I passed the flags to the configure script. Is that the correct way to do
> it?)

No, they should be set to the CFLAGS environment variable (for example):

  export CFLAGS='-mfpu=vfp -mfloat-abi=softfp -mcpu=arm1136j-s'

and after that run configure and recompile (remember to 'make
clean'!). You should see them in the lines that begin with 'gcc' if
the configure script picked them up properly.

> --> No success! It compiled fine but cpu was above 80% and playback got
> interruppted quite often.  :-(

That sounds strange, if you pass those to the configure script it
should just silently ignore them...

-- 
Kalle Vahlman, zuh at iki.fi
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