1080p @ 24fps vs. 60fps [Archive] - Audio & Video Forums


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02-01-2007, 03:34 PM
When considering specs for new equipment, why is 1080p @ 24fps preferable to 1080p @ 60fps? Or did I read that wrong?

02-01-2007, 05:35 PM
I did an involved explanation of this issue somewhere, either here or at home theater. The gist of it is that Blu-ray now and eventually HD DVD will be able to output film material in its native format of 24 frames per second. Our video system, however, is built on a platform of 30 fps at 480i or 1080i and 60 fps at 480p or 1080p. The conversion of film's native rate to our video rate requires a 2:3 cadence (every 4 frames of film translates into 10 frames of video, which means that successive frames are repeated 2 and 3 times). The few display devices at this point that can accommodate 24 fps avoid all of the problems associated with 2:3 pulldown--namely, judder and, if the processing is slow, poor, or completely absent, such artifacts as jaggies and line twitter. Though 24 fps would be preferable for this reason, it would be a mistake to think that displays without it are worthless. It wouldn't be easy for all displays to incorporate 24 fps in any event. In point of fact, 24 fps itself would be insufficient. Displays (even movie projectors) must show films at multiples of this rate (48 or 72), since 24 fps makes flicker eminently conspicuous.

Consumer DVD players and displays have been converting film's native rate into the 2:3 cadence for a long time. I'm willing to bet that most people never knew about this discrepancy between 30 and 24 fps until they read or heard about it recently, turning it into the new buzz. It's one of those phantom problems that exists conceptually but hardly at all perceptually. Don't get me wrong: The matter has some merit, but it's not a dire situation calling for immediate action (stress relief and/or a video overhaul).

02-01-2007, 08:02 PM
So if I understand this right, 24fps is rather jittery at home but fine for movie theaters and therefore needs to be multiplied to 48fps (2x) or 72fps (3x) in order to be more tolerable to the home viewer?

Do all currently available HD-DVD & BR players do 24fps and/or multiples thereof? What about the fancier up-converting (via HDMI) players, do they have any issues with this?

02-01-2007, 09:10 PM
Even in theaters, 24 fps is too slow; the frames need to be repeated. The Sony BP does 24 fps, largely because its own SXRD projector can handle it. The Pioneer 50" 1080p plasma is also capable of it, as is another display that I can't recall at the moment (maybe a Mitsubishi). I don't know of any upconverting DVD player that outputs 24 fps (or multiples of it), but, as I said earlier, conversion to a 60 fps rate is the rule, not the exception. The relationship of film to DVD involves no special issues or incompatibilities. Despite the fact that 24 fps is native to film, the oddity is for a consumer product to be compatible with it; reverse 2:3 pulldown has been a going concern for a long time, and will continue to be. Anyone basing a buying decision on support of 24 fps is creating problems, not solving them.