Question about graphics+tv RAM consumption

Christof Eb. · 2006-12-19 19:15

A question about graphics and tv objects:

In the demo for graphics there is the amount of $3000 + $3000 memory bytes reserved. - There is not much left for my application.
I already understood, that you need less memory, if you reduce the number of tiles. But I would like to have the resolution.

Is there a possibility having less colours and need less RAM? I have to admit, that I don't understand, how the TV system is working.
Is there an explanation anywhere?

Many thanks for some help!
Christof

Ym2413a · 2006-12-20 14:58

You could always try another video object. There are a good handful of video generating objects avaliable for the Propeller.

Some eat a lot of RAM while others don't, like Chip's TV-text terminal object which needs very little space.
I'd look around the Object Exchange first to see whats out there already.

Bean · 2006-12-20 15:18

Christof,
· If you only need black & white, my video overlay object only uses 6K for a 256 x 192 pixel screen.
· It will generate video even without the overlay circuit.
· http://forums.parallax.com/showthread.php?p=618061

Bean.

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Ym2413a · 2006-12-20 17:00

Yeah, Bean's object looks good too.
I've seen some screens of it. You could do some nice B-W graphics with it.

Chip has a Object that does text in color and only takes 3k if I remember correctly.
The BitMap graphics object that you find in the propeller demo just takes up too much RAM to be useful for most designs.

Christof Eb. · 2006-12-21 07:43

Thanks, Bean and "Ym2413a" for your input!

I have now found out, that it is possible to use only one buffer and get the graphics to write directly into the viedeo ram:

'gr.setup(x_tiles, y_tiles, 8*x_tiles, 8*y_tiles, bitmap_base) ' original
gr.setup(x_tiles, y_tiles, 8*x_tiles, 8*y_tiles, display_base) 'no double buffer

With this you need only half of the ram, but the picture flickers of course.

Bean, will your driver work with the graphics object?

Christof

Post Edited (Christof Eb.) : 12/21/2006 7:52:14 AM GMT

Bean · 2006-12-21 12:29

Christof,
I looked at the graphics object code, I'm pretty sure it is for 4 color/tile mode only.

Bean.

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Cheap used 4-digit LED display with driver IC·www.hc4led.com

Low power SD Data Logger www.sddatalogger.com
SX-Video Display Modules www.sxvm.com
Stuff I'm selling on ebay http://search.ebay.com/_W0QQsassZhittconsultingQQhtZ-1

"USA Today has come out with a new survey - apparently, three out of every four people make up 75% of the population." - David Letterman

Jim Fouch · 2006-12-21 14:34

The Graphics demo use double buffering to keep the video refresh solid/smooth. I use another method that does not need double buffering. It simply keeps track of what was last on the screen and only repaints the objects that have changed. It frees up an additional ~12K bytes of RAM. It's a bit more work to think about and may not work for all types of projects.

For an example take a peek at my demo www.seemeride.com

Hope this helps.

Ym2413a · 2006-12-22 00:18

The single buffering method works, but watch out if you start animating stuff.
You might run into some really nasty flickering.

But yes, It does save you some nice and much needed space.

TransistorToaster · 2006-12-23 04:32

Hello all,
Are there engines in the public domain that use more than 2 color bits per pixel?
Frank

Question about graphics+tv RAM consumption

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