Andreas -
Also, when Dodcap says 18fps on PAL video, that means it transforms 18fps into 25fps, right?
No, for PAL Dodcap converts 18 fps to 24 fps and places the result in a file that plays back at 25 fps. So your final file will play back slightly faster than the original film. If you can come up with a pattern that truly converts 18 fps to 25 fps, you can override the default one as detailed in the documentation appendix.
By the way, I haven't quite made the pulldown work 100% yet. Actually films shot at 18fps will be a bit "jumpy" after a pulldown. I've tried both with and without interpolation.
When you tried the interpolated pulldown, did you view the results on your computer screen or a television monitor? The interpolated pulldown only looks correct on the TV. It will look weird if you view it on the computer monitor.
18 fps to both PAL and NTSC presents certain challenges. The goal for PAL is to convert every three film frames into four video frames. So film frames ABC will become something like AABC. This is exactly the pattern Dodcap uses for 18 fps --> PAL if you use the whole-frame pulldown. If you want to smooth things out, you have to look at things in terms of fields instead of frames. The above pattern in fields is AtAb AtAb BtBb CtCb, where Xt=top field and Xb=bottom field. The goal in smoothing things out is to minimize the difference in the number of fields from each frame shown. For this pattern the current field count is 4 fields of frame A, 2 of frame b, and 2 of frame C. The only thing I can think of to smooth things out is to take a field from frame A and give it to frame B, like this: AtAb AtBb BtBb CtCb. Now the field count is 3 fields from frame A, 3 from frame B, and 2 from frame C, or 332. So compare the two methods: the whole frame method is 422 and the interpolated method is 332. Both represent 8 fields (or 4 frames) of video from three original film frames. Theoretically the 332 pattern should look smoother than 422 because the transition from 3 fields to 2 fields is less severe than from 4 to 2. Does this make sense? Anyway, this is the smoothest pattern I could think of for interpolated pulldown. Also, you have to remember that the 332 pattern only looks proper when viewed on a television monitor.
Still I'm not 100% happy with the results. Any inside tweak tips availeble?
Dodcap does allow you to override the default pulldown patterns. Look in the appendix of the Dodcap documentation and it explains how to do this. I was afraid someone would not like certain patterns, so I added the override capability. If you can come up with a pattern that looks/works better, you are welcome to override it, and let me know as well. I might want to replace the one that is there now if yours is better!
Hope this helps! Let me know if you experiment with other pulldown patterns. In Dodcap's defense, all I can say is that A) I am always open to suggestions, and B) at least you can override the default settings if you wish!
Thanks for the suggestions/comments!
- Jeff Dodson
