Many of the DVD players I notice will play unauthored MPG (i.e., just burned as an ISO disc)

I'm wondering if there are the same restrictions, in general, for unauthored video as there is for authored video. In other words, can I use non-standard resolutions (i.e., 320x240 or any non S/VCD resolution) and/or non-standard framerates (30 fps, 15 fps, etc....) and expect to have my video play with correct aspect ratio?