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

[From: 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.

-- 
Kalle Vahlman, zuh at iki.fi
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