I have been playing around a little with HD dvd burning in DVD Studio, just to satisfy my curiosity so far. one restriction you have with your source files is that they seem to have to be at 50fps for PAL and 60fps for NTSC. What I have been doing with my video clips is up-converting them to the correct framerate, so for example with a 24fps source you end up with a 3:2 pushup (just made up that phrase - dont quote me on it) like so... frame1, repeat, repeat, frame2, repeat, frame3, repeat, repeat, frame4, repeat and so on. now having all these repeated frames is not efficient at all, and the great savings on filesize that H.264 offer us are wasted because we need to have 66% more frames in our video than we actually need. Does anyone know if the final HD DVD Spec will support a broader range of frame rates, or alternatively if there will be some kind of flag to set in the video track, similar to the 24fps pulldown flags that we have with DVDs?