Hello,

On the last weekend I tried to get familiar with powerpc altivec assembly  and
added some optimization for sbc encoder. Experimental patch is attached. It
handles 4 subbands case only, so is not that much useful in practice. There
are no problems supporting 8 subbands too, but I was just running out of
time. The patch merges processing of 4 blocks into the single block of code.
It's something that is also in my todo list for ARM NEON. But while this merge
is mostly "nice to have" optimization for ARM, it is much more important for
PowerPC because of a huge multiply-accumulate latency.

And bluez a2dp seems to work fine on ppc64 linux (playstation3).

In order to activate altivec code, -maltivec option needs to be added to
gcc compilation flags.

Benchmark result:

time ./sbcenc -s4 somefile.au > /dev/null

before:
real	0m13.999s
user	0m13.468s
sys	0m0.523s

after:
real	0m5.714s
user	0m5.199s
sys	0m0.519s

3.2GHz CPU in playstation3 uses roughly 1.5% of cpu resources on sbc encoding
without any optimizations. cpu usage is down to something like 0.6% after this
optimization is applied.

-- 
Best regards,
Siarhei Siamashka