Originally Posted by Medieval Guy
Later this week, I'm getting a 600hz TV after having a 60hz. Currently, I have the 1080p24 Output set to Off. The Unofficial FAQ recommends On. Will that only send 24hz content in 24hz, or will it monkey with 60hz material as well? That is, is On really best, or would I be better off with Auto?
I always recommend folks leave it at AUTO in case they try a different TV in the future and forget about that setting.
1080p/24 AUTO sends 1080p/24 when the source content is 1080p/24 AND the Display says it can accept 1080p/24 during the handshake.
1080p/24 ON sends 1080p/24 when the source content is 1080p/24 REGARDLESS of whether the Display says it can accept 1080p/24 during the handshake. This is specifically for some notorious projectors that work just fine with 1080p/24 input but fail to publish that fact during the handshake.
With EITHER setting, you will STILL get 1080p/60 if the source content is not 1080p/24 to begin with.
Contrast with the DVD 24p Conversion setting which will try to render an SD-DVD as 1080p/24 even if it can't find a film rate cadence in that video. This allows it to carry through brief portions of an otherwise film-rate SD-DVD that don't convert cleanly to 1080p/24, but does mean the user has to be alert for "frame drop stutter" as a sign that this SD-DVD really is not appropriate for Conversion -- and thus the DVD 24p Conversion needs to be turned OFF, manually, by the user. That will be true if the SD-DVD content was never film-rate to begin with (e.g., an SD-DVD of a TV show), or if the method of creating the SD-DVD transfer makes it impossible to recapture the original /24 stream due to faults in the cadence or lack of a uniform cadence to begin with.
FOR NEWBIES: DVD 24p Conversion is used to eliminate "cadence judder" -- a minor ratcheting effect in otherwise smooth motion due to the conversion of film rate content (24 frames per second) to TV rates (30 or 60 frames per second). Since 24 doesn't divide evenly into 30 or 60 that means some film frames end up on screen slightly longer than others. You've been seeing "cadence judder" your entire life -- any time you watched a movie on a traditional TV set. The brain is very good at "not seeing" cadence judder. Most people can't spot it even if it is pointed out to them, unless a "judder free" playback is available for side by side comparison. A common place to look is in the smoothly scrolling end credits at the end of a movie.
Movies are recorded on SD-DVD already configured for playback on traditional TVs -- i.e., at 60fps. The process of doing this -- called Telecine -- involves repeating certain interlaced half-frames (called fields) in a regular cadence. It is this repeat which leaves them on screen slightly longer. DVD 24p Conversion is designed to remove the repeats leaving the original, 24fps film stream. This is ONLY worth doing if your TV will take 1080p/24 input and "do the right thing" with it -- meaning it displays it at a "refresh rate" which is a multiple of 24 frames per second -- 48, 72, and 96 fps being the most common.
Video rate content is originally recorded at 30 or 60 fps. If you try to force that to 24fps, that HAS TO FAIL, because there is no way to know which frames are "safe" to discard. The result of forcing video rate content to film rate is "frame drop stutter", a jarring unevenness in motion due to frames of the original video content having been discarded. Frame Drop Stutter is most easily seen in things like horizontal camera pans at modest speed, because the entire image is in uniform motion. Frame Drop Stutter is much MUCH worse than Cadence Judder. It is impossible to ignore.
So, if you have enabled DVD 24p Conversion and start seeing gross, jerky motion in pans, that's your cue you should go and turn OFF DVD 24p Conversion (which you can do "on the fly" -- while the movie is playing). It means that either this program was originally video rate content (and thus not something you want to Convert) or it was film rate content transferred to SD-DVD in a slipshod fashion that makes it impossible for DVD 24p Conversion to find and extract the original 24fps stream.
Again, Frame Drop Stutter is nasty. Cadence Judder is easily ignorable. You can leave DVD 24p Conversion OFF all the time and just live with Cadence Judder (if you can even see it), or you can use DVD 24p Conversion -- for movie discs only, and generally for newer disc transfers of newer movies (which are more likely to have a recoverable 24fps stream) -- and just keep in mind that if you start seeing Frame Drop Stutter, that's your cue to turn DVD 24p Conversion OFF while viewing this particular movie.
If you have the SD-DVD for "Shakespeare in Love", there's an easy way to familiarize yourself with the differences. That disc includes two instances of the animated Miramax logo, which pans upward.
One instance shows while loading the disc BEFORE you get to the Root Menu. It is on disc as video rate.
The other instance shows when you start the movie playing. It is on disc as film rate.
Try comparing both with DVD 24p Conversion ON and OFF. With it ON, that first one will look distinctly jerky. THAT'S Frame Drop Stutter.
With it OFF, *BOTH* of them will look smooth in motion! Yes, BOTH of them. Why?
As it turns out the first one is rendering smoothly in video rate, and the second is appearing to render smoothly even though it includes "cadence judder", because the brain is so good at ignoring "cadence judder".
If your TV accepts 1080p/24 input and "does the right thing" with it, you can turn on DVD 24p Conversion and that second instance of the logo will now go to your TV as clean, 1080p/24. I.e., without "cadence judder". Can you see the difference? Many people CAN'T. That may be because they are not sensitive to that minor ratcheting, or it may be that their TV is displaying that 1080p/24 input as 1080p60 -- i.e., it is NOT "doing the right thing" with it, but rather re-introducing the "cadence judder" you just removed!
In any event, that minor difference -- eliminating "cadence judder" -- is what DVD 24p Conversion is all about. If you can see the improvement in the motion of the 2nd logo with DVD 24p Conversion ON, then you will likely enjoy experimenting with it while playing SD-DVD movies. You can use this "Shakespeare in Love", SD-DVD as a test case, for example, as it has a "clean" Telecine cadence.
The thing you want to keep firmly in mind is that the jerky motion you saw with that FIRST Miramax logo -- i.e., prior to Root Menu, and with DVD 24p Conversion ON -- is Frame Drop Stutter. As you can see, it is pretty darned obvious. You definitely do not want that. And that will give you an idea of the type of thing to watch out for when playing any random SD-DVD movie disc with DVD 24p Conversion ON. If you see that significant hurky-jerky motion in pans (for example) that's your cue to go turn DVD 24p Conversion OFF and enjoy the movie "normally". Yes, still with "cadence judder", but still looking much better than if you try to convert a disc to 24fps that's simply not suitable for conversion.
I should add that this DVD 24p Conversion stuff *ONLY* applies to SD-DVD shiny discs, and only in NTSC markets (480i/60 content)
Conversion is not available for other 480i/60 content -- e.g., media files.
SD-DVD discs for Europe (PAL format) don't use Telecine, so no Conversion there either.
And movies on Blu-ray discs are already recorded on disc as 1080p/24 -- so no Conversion is needed.