[vorbis-dev] vorbis on playstation 2
segher at koffie.nl
Wed Feb 5 23:11:26 PST 2003
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>--- >8 ----
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