Re: Apple II Music Video - Welcome to the Jungle!!

["Michael J. Mahon" <mjmahon@aol.com>]

Frank M. wrote:
> Thanks! i think it looks pretty cool, too! thanks for the code,
> michael. i was so focused on getting a proof-of-concept that my code
> was a bit sloppy. and i actually didn't know you could use offsets like
> that in ProDOS (i was always more of a dos3.3 guy since that's how the
> bootleg of Hard Hat Mack showed up and also because hard drives were
> something we never used). it will be even better when/if we can get it
> running at 25 frames per second. that's when the dithering effects will
> really stand out, i think. i could write a quick program to load larger
> chunks of frame data into high memory and then just rapidly swap banks
> of memory into the GR screen. you could probably do hundreds of frames
> a second that way. problem is that you can only fit so many frames into
> RAM before you have to do another disk access. maybe it could be fast
> enough to fit into the delay between swapping frames.

Yes, ultimately you can't sustain a frame rate faster than the
bandwidth of the hard disk.

Using Applesoft (BASIC.SYSTEM) to read the frames requires that the
file be opened and closed on each access, which is substantial overhead.

A short M/L loop (essentially the FOR loop in my program) could do
the job without the open/close overhead, delivering faster frame
rates on a 1MHz Apple II.

> i'm rendering a couple more movies today, so there'll be other things
> to work with. i realize the dithering method i'm using isn't perfect.
> i'm not as much a programmer as i am an imaging nerd (photoshop is my
> 'day job'). since i'm currently using photoshop to do the downsampling,
> i'm sort of constrained by what i can automate. but i can see how it is
> possible to write an application that you run a quicktime movie through
> and it produces these 13,707 block files formatted and ready to go. and
> on top of that, 40x48 pixels isn't really a whole lot of information to
> work with, so it only follows that you'll lose some information.

Actually, upon several re-viewings, I see that there is already a fair
amount of time-domain dither, like in the noise in the background.

Like you, I find that backing up about a meter from my monitor and
taking off my glasses (I'm nearsighted ;-) does wonders by allowing
my brain's pattern recognition to work without the distraction of
sharp-edged pixel detail.  ;-)

> you realize the next step is running a sample using DAC522 during the
> delay between frames, right?  ;)   even though there was never much of
> a demo-scene for the A2, it's never too late to start.....

That would be great, but it would require another Apple II, since
DAC522 also uses 100% of the machine.  ;-)  Then there's that nasty
problem of not having 3MB RAM for the whole song, and not being
able to stop even for an instant to do I/O...

Now, maybe a IIgs could do it, since the DOC plays sound independent
of the processor--and 2.8MHz wouldn't hurt the frame rate, either.  ;-)

> Michael J. Mahon wrote:
>
> > Frank M. wrote:
> >
> > > Here's the code for rendering the lores photoshop TIFFs onto the A2 GR
> > > screen.....
> >
> > Frank, it's pretty awesome to watch the results of your rendering
> > on an Apple II!
> >
> > I notice lots of sequences where there are regions containing
> > very little detail.  For example, outlines of figures are
> > often visible, but any detail in the figure is missing (which
> > would be expected if the figure is only a silhouette in the
> > original).
> >
> > Have you considered using dynamic thresholds between colors that
> > track "median" colors of regions, so that details would tend to be
> > rendered instead of "falling into the same color bucket"?
> >
> > If a little noise were introduced into these thresholds, it would
> > also add time-domain color dither, which would have the effect of
> > increasing the palette.
> >
> > I realize that I'm talking about an adaptive algorithm that may
> > have to be "custom" instead of a pre-built image filter, but maybe
> > this has already been done to handle the "posterization" operation...
> >
> > I think that a little increase in color distortion would be a small
> > price to pay for increased visible picture detail.
> >
> > -michael
> >
> > NadaNet networking for Apple II computers!
> > Home page:  http://members.aol.com/MJMahon/
> >
> > "The wastebasket is our most important design
> > tool--and it's seriously underused."


--

-michael

NadaNet networking for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
tool--and it's seriously underused."