[vorbis-dev] vorbis on playstation 2

Segher Boessenkool 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 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'vorbis-dev-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.

More information about the Vorbis-dev mailing list