[vorbis-dev] vorbis on playstation 2

[Segher Boessenkool]

Brad BARCLAY wrote:

> 	Of that ~90%, 14% was being used by _fpadd_parts.  Alot of time
> appears to be wasted while doing floating point arithmetic, probably
> due to the fact that Vorbis uses lots of double-precision floats, which
> are emulated on the PS2.

There shouldn't be any double precision floats -- please report these
as a bug (bugs.xiph.org).  Except maybe in lsp/lpc stuff (but that's
ancient, and not used in 1.0 files anymore; your application doesn't
need to support floor0 at all, probably).

> 	Of the actual Vorbis sources, 12% of the processing time is
> spent in mdct_backward (mdct.c).

That's one of the big cpu hogs, as expected.

 > the next most used is 9% by
> vorbis_book_decodevv_add (codebook.c),

That one, too.  Ideally, cpu usage outside these two is < 10% or so.

 > and 4% is used by ov_read
> (vorbisfile.c).  Of these, the first two are probably good cantidates
> to porting to vector assembly.
> 
> 	Cache miss is also fairly high -- nearly 50%.  Again,
> mdct_backward appears to be the biggest culprit.

MDCT should run fully from cache.  How big is your cache?

<p>Segher

<p>--- >8 ----
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