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

[Joel Sherrill]

Craig Graham wrote:
> 
> 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.
>
> Reasoning:
> 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.

:(  Well that sounds like we are going to have to look at
"preprocessing"
files on the host side and only giving the GBA something lighter.  I
guess
the next step in the "feasibility study" is to see how the size of an 
Ogg or MP3 file compares to the raw bit stream required to drive the
sound chip on the GBA.
 
> Of course, if you prove me wrong I'm first in the first in the queue to stick
> it on my GBA ;)

:)
 
> Craig.
> --
> 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...

-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel at OARcorp.com                 On-Line Applications Research
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