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

[From: Kalle Vahlman]

2007/1/29, Simon Pickering <S.G.Pickering at bath.ac.uk>:
> > > 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.

Now that we're on the topic, let's bring this bit into the conversation too:

  http://marc2.theaimsgroup.com/?l=qemu-devel&m=114364317919922&w=2

So if you use the "-mcpu=arm1136j-s", you'll likely need sbrsh as the
CPU transparency since QEMU won't handle the produced binaries. I
tried to build glib for example and the docs failed since it compiles
a tool and runs it in the genrating process.

After setting sbrsh up with my N800, it was all peachy (haven't got
time to produce numbers on how peachy it'll be, but I'm working on it
;).

-- 
Kalle Vahlman, zuh at iki.fi
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