Ogg+RTEMS on GameBoy Advance was Re: RTEMS device driver andinterrupt

Craig Graham craig at data-uncertain.co.uk
Fri Apr 12 19:04:19 UTC 2002

On Friday 12 April 2002 8:28 pm, you wrote:
> Mike Panetta wrote:
> > On Fri, 2002-04-12 at 11:32, Joel Sherrill wrote:
> > > Mike Panetta wrote:
> > > > Thinking GBA are we?  An ogg player for the GBA might be pretty neat.
> > > > Esp if it had some sort of visualization like winamp or whatnot.
> > >
> > > Busted.  So the big question now..
> > >
> > >   Is this a feasible project from a HW perspective?
> > >
> > > The GBA has 16 Mhz ARM, 32K+256K RAM, <= 256Mb flash, and as best
> > > I can tell 8 bit stereo.  I know the sound won't please an
> > > audiophile but is this doable given the HW limitations.
> >
> > I think we would need to have your previous question answered first,
> > before we could make any educated guesses on that.  I myself do not know
> > much about the ogg format to guess :).  As for ram, I bet it would not
> > be too hard to add some external ram where the flash would normally be.
> > You would just need some sort of burst counter and address demux in an
> > external CPLD I think.  The only thing I can think of that would prevent
> > it would be if the GBA disalowed writes to the ROM address space.  The
> > burst counter and demux would be needed to interface flash anyways if I
> > read the schematics right on the pages I looked at, so its not much
> > added effort.  I do know about the RAM space that the GBA cartrage has,
> > but it would only allow you to add an additional 64K of ram IIRC, which
> > would not be significant (or would it?  I guess we would need to know
> > buffer size requirements to figure that one out).
> I would prefer to be able to stick to off-the-shelf flash cartridges
> for the GBA.  So even preprocessing files to a "game boy audio" format
> on the host side would be OK by me if it made processing easier on
> the GBA side and did not explode the size of the files.

I don't think you'll manage to play ogg files on GBA.
It took almost the entire processing power of a Playstation1's R3000 core to 
play an MP3. MP3 & Ogg have roughly the same processing requirment.
The PS1's R3000 was clocked at 30MHz, which is a fair bit faster than a 16MHz 
ARM. QED, it won't work.

Of course, if you prove me wrong I'm first in the first in the queue to stick 
it on my GBA ;)

Craig Graham <craig at data-uncertain.co.uk>
Technology is like a war fought with symbols, words and gestures
- all you have to lose is everything, so trust no-one...

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