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Beginners > GBA Video

#33536 - Meekay - Wed Jan 05, 2005 2:42 am

Hi everybody... I'm brand spanking new to this forum (and also to the world of homebrew game creation) and I had a question. I've been toying around with the idea of doing something like the GBA video cartridges seen in great abundance at my local Wal-Mart.

I did a little research, and stumbled upon the Caiman codec site. It seems like something that I could use to achieve my goal... Except it hasn't been updated in months, and I have yet to recieve a reply regarding my request for licensing information. So I think I'm pretty much back to being in the dark...

Anyway, I was wondering how feasible a project of this nature would be (especially from a beginner's standpoint), has the process been documented, do I need any different hardware than the standard stuff you guys advertise on the site, etc?

For me, it doesn't really matter if the video has scene skip/ff/rewind controls (that can come later). I just want to start off getting a small video playing.

Thanks for listening!

-Mikey
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If you aren't part of the solution, then you're part of the precipitate.

#33538 - DekuTree64 - Wed Jan 05, 2005 3:28 am

Generally video is one of the more challenging projects to take on for the GBA, but since you'll probably just be doing straight bitmap mode calculations, you won't have to learn all the tricky details of sprites/BGs/etc.
If you already have some video coding knowledge, you should be able to pretty much jump right into it as soon as you get a project to compile and set a couple of registers. And judging by how all the good codecs have been bought up so far, you could probably get yourself a pretty good chunk of change when you're done too :)

Anyway, I'd suggest using VBA at first to get it up and running, so you don't have to invest any money in it. Once it is working though, you'll probably want to get a flash card to make sure it runs at a reasonable speed.
_________________
___________
The best optimization is to do nothing at all.
Therefore a fully optimized program doesn't exist.
-Deku

#33578 - Meekay - Wed Jan 05, 2005 7:30 pm

By video coding, you're referring to the actual writing of the compression/decompression algorithms, correct?

I've done a passable amount of video editing, but I have yet to actually sit down a write a codec for my movies... Any good jumping off points for this, as well?
_________________
If you aren't part of the solution, then you're part of the precipitate.

#33587 - DekuTree64 - Wed Jan 05, 2005 8:34 pm

Yes, I was referring to writing your own codecs. That will be your biggest challenge then, but it's certainly doable. There's a thread going on here where ScottLininger and I were discussing a possible codec based on the GBA tile modes. You'll probably want to go with bitmap mode though, since it's been proven possible, and the tiled one is more of an experimental idea wondering if it would really work well at all. Still, you might be able to use some similar techniques, like the screen coverage bitmasks I described in the last message there, and covariance mentioned by Tepples.
Basically the idea of a video codec is to recycle as much of the old data as possible, by either leaving it alone, or doing different transformations on it. Then you can add in bits of lossless compression like RLE, LZ77, huffman, etc. to compress pieces of your data even further.
_________________
___________
The best optimization is to do nothing at all.
Therefore a fully optimized program doesn't exist.
-Deku