spiritofcat you just described shutter glasses but there are some polarised light type 3d options available* in general consumer land- the 3DS though is something like those "moving" or dual picture things you might have seen as a kid (the technical term is Lenticular printing) with the thin strings of transparent plastic on top but many times more advanced. This is why glasses are not needed and also why it probably does not have the best viewing angle. In what I imagine is a patent minefield LCD screens were once renowned for bad viewing angles vs crt but in some cases similar technologies/methods were used to improve it.
*granted the TVs (or more likely projectors) are usually circular polarisation but the idea in linear polarisation is that light as a wave can move up and down and if it is the case you can block it by having a filter (in practice just a few really narrow strips of material with gaps between them). Show one image in one polarisation and one for the other eye in the opposite and you can effectively show a different image to each eye and thus gain 3d.
To this I will echo my previous comment- technically there should be no problem. In practice it will come down to encoding/display methods- if it is "lenticular" in nature it will look very odd. If you know video imagine combining the fields of two different videos but if not I hate deep linking a site (especially one I respect) but courtesy of frames I am going to have to
http://www.doom9.org/video-basics.htm (main site is
http://www.doom9.org ), do a page search for "And the corresponding frame:" and now rotate it 90 degrees. To speculate the "3d slider" probably merges/reduces these to adjust the 3d effect.
Such a thing is a nightmare to encode efficiently using traditional methods (games being generated are not bothered in the slightest by this beyond the obvious having to generate two images) as lossy encodings work by assuming their neighbour is similar to them (see picture on the link for why that would not work) and that the next frame is also similar* in case you were thinking about alternating frames and the extension avi is short for audio video interleave which came about to stop the playback device having to skip all about a disc to read the file (the vast majority of containers having similar behaviours) although it probably will be the best route to try out.
Were I to be a coder on the hypothetical 3ds 3d film playback/encoder project (assuming the rest of my post is correct of course) I would look at interlaced video storage, playback and handling as it is extremely similar. This would be the "bit of fiddling on the part of the encoder" I mentioned earlier.
*the difference being any movement in the picture which is actually calculated/account for, similarly if you have ever seen a broken video fuzz up into probably a nice grey, green or pink block and come back according to what moves first you now know why. The reason it might all pop back in at once is usually because a complete frame (i-frame) that does not depend on what came before (or after) is often part of the video. Indeed generating these in the first place is a reason why encoding often takes so long or in the case of high end filters like mvtools (
http://avisynth.org.ru/mvtools/mvtools.html ) takes so many resources but produces such spectacular results vs more brute force methods.
Now of course Nintendo having to build to cater to the public at large is not going to want to do a crash course in video encoding for them and equally the only real use of it being to watch copied* (copyrighted- fair use maybe but anybody who has followed this arena since the days of decss knows how this game works) videos which others may frown upon and might come as part of a decoder license.
I know the ability to make your own was touted for the 3ds itself but recording video is quite different in this case from converting it. Your best bet here then is Nintendo leave it open for sharing videos between such devices (quite likely if you ask me) and some seriously bright spark reverse engineers it. That might not be a case of I will hold my breath though as that is a horrific task; this is a breakdown of MPEG 1
http://www.cmlab.csie.ntu.edu.tw/cml/dsp/t...g/coding/mpeg1/ so imagine trying to work that backwards and then consider MPEG1 is ancient and incredibly simple relative to modern formats which the 3ds will not only lean on but probably tweak (see post above) making it even more difficult. You can hope they will use something known just with a nasty container or hope the SDK leaks but again I would not hold my breath.
