Do digital projectors have a set fps?

[Chamber005]

I think this would be interesting to know for all the Indie film people -- Especially those who might shoot something on a Mark 5D 2 or something where you can't change the fps --

Will movie theatres that have digital projectors play footage at any fps? Can they do 30 or 60 or what have you?

It seems like everyone is stuck on this 24/25fps in digital cinema, but isn't that only truly important if you plan on transferring it to actual film? I understand that, for some bizarre reason people want a film's fps for the "look" of it, but for the rest of us who don't care, can those flicks be shown in theatres that have digital projectors?

And if so, what do digital projectors actually use? Like, what does the digital data (or tape) have to be download to and delivered to the theatre on?

THANKS!

 

[Chamber005]

Bump

 

[qazwsx]

pretty sure most modern digital cinema projectors support 24, 30, 60 and 48 (for 3D) progressive frames per second.

i think jpeg2000 is the professional means of delivery. however, i've seen a lot of different things hooked up; from hdcam all the way to a ps3 playing back h.264 files (and games of course).

 

[j1clark@ucsd.edu]

I think this would be interesting to know for all the Indie film people -- Especially those who might shoot something on a Mark 5D 2 or something where you can't change the fps --

Will movie theatres that have digital projectors play footage at any fps? Can they do 30 or 60 or what have you?

It seems like everyone is stuck on this 24/25fps in digital cinema, but isn't that only truly important if you plan on transferring it to actual film?

If the digital refresh rate is 120 HZ that's a multiple of 24, and so, would not introduce the artifacts that are seen at 30/60 Fps, of 'normal' TV display. If the projector's refresh rate is 30/60 or uneven multiples of 24, then there will be the same problems as 30/60 HZ.

PAL places get away sort of with 'cheating' by running 24 fps material at 25 fps... if shooting film, shooting at 25 fps in the first place...

 

[Chamber005]

Hm...

This isn't completely my department, but I'm wondering how 35MM shot at 24fps might be able to be interlaced with HD footage shot at 30 or even 60 and then played on a digital projector. Like, if you're not interested in a "film look" to be projected on all of your footage, how would that be possible in terms of projection? Are the projectors advanced enough to switch between the different speeds depending on the information that's coming in?

 

[j1clark@ucsd.edu]

Hm...

This isn't completely my department, but I'm wondering how 35MM shot at 24fps might be able to be interlaced with HD footage shot at 30 or even 60 and then played on a digital projector. Like, if you're not interested in a "film look" to be projected on all of your footage, how would that be possible in terms of projection? Are the projectors advanced enough to switch between the different speeds depending on the information that's coming in?

While I don't know about specific digital projectors, the basic display systems used by most computer projectors use a refresh rate based on the computer driving the projector. The origin of the 60 or 50 HZ field rates were based on the use of the power company to provide a synchronizing signal, namely the sinusoidal wave of the power coming over the lines. The power companies had much better regulation of this frequency than early TV's...

I would imagine that any modern projector, espeically fancy ones used for the presentation of 'film' material, will have refresh rates that are multiples of the basic frame rate of the material. So a projector set up for 24 fps film, should have the refresh rate some multiple of 24.

In the case of mixing material shot at different rates, well, recall that 'least common multiple' business at school... here's an application...

I think 120 would be the least common multiple of 30, 60, and 24...

let's see...
30 factors to 3 * 5 * 2
60 factors to 3 * 5 * 4...
24 factors to 3 * 8...

Using the highest power of each prime, 2, 3, 5, one has

8 (2 ^ 3) * 3 (3 ^1) * 5 (5^1) = 120...

Now if your projector runs at a refresh rate of 75... well, get one that has more capability... or put up with small little 'glitches' in the displayed film...