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Subject: Re: iPod's framebuffer format

Re: iPod's framebuffer format

From: Jacob Rau <jacob.rau_at_gmail.com>
Date: 2006-07-08

I realize that we probably aren't at the speed to play compressed and/or
high-quality movies smoothly, but I plan to make the plugin flexible so that
I can set the framerate very low, making this possible. Maybe I'm missing
something, but it looks like I can run the "cube" demo plugin and play my
music at the same time, without any hiccups, and the cube demo runs at a
fairly decent frame rate. Is Cube doing anything special to increase frame
rate, like dirty-rectangle updating? (forgive me, the code is on my other
computer right now)

Thanks for the info. I'll try to write a demo app for this tonight just to
see if this is feasible right now.

Oh, just thought about it--this may be feasible on the nano right now, but
the ipod Video might be harder with its bigger screen. Oh well. It's still
worth a try.

Thanks a bunch,
Jacob

On 7/8/06, postmaster@diffenbach.org <postmaster@diffenbach.org> wrote:
>
> Oh.
>
> Currently I don't think we have the requisite code speed to play
> movies on the ipod. To get there, we'll need at least two things: a
> faster memcpy and faster video routines.
>
> I've been working on an assembly language memcpy to help with this;
> currently it is faster on large copy lengths (the slope of the line is
> less) than either the linux kernel's or uclinix's memcpy. (And faster
> than the C memcpy we currently use.)
>
> For all copy lengths, the absolute speed is always lower than the
> linux kernel's memcpy.
>
> For word aligned data or same aligned data, the absolute speed is also
> always less than uclinux's. But uclinux's memcpy has a faster absolute
> speed for mixed aligned data when the copy length is < ~64 bytes.
>
> Jacob Rau wrote:
> > Hey list,
> >
> > I''ve been thinking about writing a plugin that will play movies on the
> > iPod Nano, but what I don't understand is the frame buffer format. I see
> > a few of the plugins fill it full of hex, but I don't know how to
> > decode/encode to/from this format. I realize I may have missed a wiki
> > page, but seeing as twiki is down now even the briefest of explanations
> > will do. Example code would be nice, but I guess that's what the other
> > plugins are for.
> >
> > Thanks for putting up with my ignorance...
> > Jake
>
Received on Sat Jul 8 22:41:02 2006


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