It's me again. Sorry.
Whenever there's talk of a DS-port of Final Fantasy VII, sooner or later people will start talking about whether or not they could fit the game on one of them DS cards, agree that they couldn't, and start talking about making larger cards or employing a system of card swapping.
Also, whenever this happens, nobody actually does the research and the calculations. So I did. And these are the facts:
The largest available regular DS cartridge is the 2 gigabit card, which as we all should know by now is 256 Megabytes. Flashcards hold 2GB and more, but for some reason Nintendo decides not to use cards that hold that much space. A PlayStation CD holds about 600MB, and Final Fantasy VII had three of them. So no way the game could fit onto a 256 card, right?
Wrong. First, let's take a look at the DS specs in comparison to the PSX:
- The PSX has a 33mhz CPU, the DS has 67mhz. This isn't all that important and the DS is not "twice as fast" as the PSX, because what matters is the GPU and the 3D rendering capabilities.
- The PSX has a relatively powerful, easy to program GPU with a maximum of 180.000 texture-mapped and light-sourced polygones, and it has 2MB RAM
- The DS can put out a maximum of 120.000 such polygons, but has a more powerful 2D GPU and 4MB of RAM.
- The PS1 has video memory of 1MB, the DS has 656KB.
What does this mean? It means that the PSX can do better 3D, and the DS can do better and faster 2D. Final Fantasy VII was never known for it's high polycount or it's good textures. Quite the opposite, many characters and enemies only had gourad shading (a single color with lightning information), which the DS is perfectly capable of.
The DS should have no problem with the 3D content, and should be even faster and more accessible when it comes to the prerendered backgrounds. Worst case scenario is they have to lower the polycount in battles a bit, which might not even be noticable due to the small screen size.
I always thought the 256x192 is too low and that they had to find ways to somehow put the dialogue on the bottom screen or something, but I recently put a gameplay-video on my DS via moonshell, and was surprised: Everything can be read perfectly, even the menus. It actually isn't necessary to change the game in any way to be playable on the DS.
Now let's look at what is actually found on these three discs.
Final Fantasy VII has 723 different prerendered backgrounds in a resolution of 320x224 pixels. Many of these had to be put on each of the three discs. Not only that, but these images are uncompressed - The original Final Fantasy VII backgrounds have an average file size of over 150kb! All image data from the three discs combined accumulate almost 300MB of uncompressed images!
The DS screen's resolution is 256x192. Put every 723 different backgrounds on a single card so that you don't need doubles, downscale them to 256x192 pixels with modern image compression and minimal quality loss, and those 300MB of image data shrink down to 40MB. We just reduced the size of the image data for the entire game by 86%.
Final Fantasy VII had 24 channel midi music. In case you don't know, MIDI is very, very small. It's tiny. I don't have exact data, but I imagine the entire soundtrack in midi format doesn't take up more than 5-10mb per disc, probably less.
The DS has a maximum of 16 channels, so just like with FInal Fantasy VI Advance they will have to remix smaller versions of the tracks. And again we don 't need doubles. Music will not take up more than 5MB of space. (If they decide to replace "One-Winged Angel" by a MIDI. If not, add 5MB)
This is where it gets interesting. DS developers hate voicework and FMVs, because even compressed they fill up those 128/256 MB pretty fast.
Final Fantasy VII has about 50 Minutes of FMVs, 320x224 pixel resolution @ 300kps, again there's stuff repeated on the discs.
There's some stuff that could be done better with polygons nowadays (elevators and stuff) and I don't think the DS can handle the sequences were you're controlling a polygonal character through a FMV scene, so I think a FFVII DS should cut some of the sequences, but let's just assume we're talking about 45 Minutes of FMV sequences here.
45 Minutes of compressed fullscreen DS-movies, 256x192 pixels, with 288kps, 15fps and 33hz 2Channel sound at 128kbs = approx. 75MB.
And that's it! 75MB of video, and that's full screen with sound. Many videos don't have extra sound, only the MIDI. Most DS games also don't use the full screen for videos, making them even smaller. And there's tons of stuff that doesn't need to be on there, and things that can be told in-game.
4. GAME DATA
All the other stuff, background depth information, dialogue and code. Not counting the stuff that is repeated on the discs. Including a lot of garbage data, we're talking about another whopping 133MB here, by compression standards of 1996.
This can be compressed significantly, I'd say to 80MB at the worst.
So, we have:
Gama data: 80MB
Background data: 40MB
200 MB of a complete Final Fantasy VII when put on a single medium with modern compression techniques.
It's close, and I might be off on certain points. And even if it didn't fit on 2Gbit, 3 or 4 Gbit should be more than enough!
Say what you will about a DS port, but by my reckoning, space shouldn't be an issue.