[vorbis-dev] ogg vorbis dynamic memory allocation.

[Segher Boessenkool]

Firelight Multimedia wrote:
> 
> Hi,
> I finally got around to overriding ogg_malloc etc and running through my
> memory manager.  Thinking of limited memory consoles like PS2, I was

How much RAM does a PSX2 have?

> somewhat alarmed at what I found .. Admittedly I am using vorbisfile but
> that’s because its so easy to use :) ..

Vorbisfile shouldn't be a big overhead over straight libogg/libvorbis;
if it is, it's time we do something about it.

> Per ogg file my memory manager is telling me it is using 885,201 bytes
> per file (I thought I would maybe get a constant overhead and lower
> overhead per file but its 885k each time).

That's way too much, I think... you might forget to free memory?  If you've
overridden alloca() as well, you need to free that memeory at function
exit of the function that did the alloca() (or per C block, even).

> Ov_read reads 17k at a time in my streamer, and reducing it (to say 7k)
> made no difference.
> Is there a way to get this right down?  Remove vorbisfile I assume is
> the first thing (though I am loathe to do right now due to the extra
> complexity involved).  Mp3 currently uses about 32k of different buffers

That's not right; the tightest mp3 decoder I've seen needs about 48k
R/W memory, and there's not much opportunities left to reduce that.

> per file which is extremely efficient memory usage for consoles, is
> there any way vorbis might be able to get this low?

There's work being done to reduce Vorbis memory usage (as well as cpu
usage, and cache pressure).

> I havent had a look at static usage yet, id have to take a look at the
> map file for that.

> Any ideas or comments appreciated.

You can mail me your malloc() etc. implememntation, and I'll have a
look at it; and/or the raw output of your mem usage experiments.

Cheers,

Segher

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