24fps and sync questions

[Andreas Wideroe]

I have a few questions:

A client is going to shoot a music video at 24fps and needs lipsync without using crystal sync cameras. (It's hard to borrow 15-20 crystal sync cameras in Norway). He will therefore shoot at 24fps and will do post sync on a computer. I will transfer the films and convert them to 25fps.

- My question is: What is the best way to transform 24fps into 25fps? (Digivid, Will Dodcap be my best choice?)

- What is the exact length of a super8 film shot at 24fps? My calculation is 2 minutes and 30 seconds: 3600(frames)/24/60=2,5min. Is this correct? The song lasts 2 minutes and 38 seconds. He wants to shoot all in one take with 15 cameras at the same time.

- With crystal sync; For how long can a super8 camera shoot in 100% (or 99.9%) sync, meaning how stable is crystal sync?

- How stable are normal to good cameras running at 24fps? Will they stay 24fps or will this change over time?

Any help is highly appreciated!

Cheers,
Andreas

[S8 Booster]

Just to throwing in a few ideas:

Seem to be a rather complex project as I believe it is difficult to get 15 x-tal sync cams available.

Anyway, one sync or x-tal synced camera for a "master shot" that fits 100% sync to the audio track will help a lot as it is possible to jig saw puzzle limited lenghts of clips the from the other 13-14 un-synced cams with the master shot.

If you look at a typical "busy" music video around a lot of the "fill stuff" is hardly sync required at all only when there are closeups of singing artists or instruments clearly visible.

So with "creative editing" this will work.

With a x-tal sync or reasonably natural synced camera (tests required) a 15m cartridge will last 2:30 at 24 fps so it all cams are started at the same time you will be 8s short. However, what about starting a few of the cams (50/50?) a little delayed so the total duration will be sufficient. Say delay 50% of the cams 30-60 seconds. Besides using 2 x-tal synced cams that are started sequantially one with 30 sec delay to ovelap the missing 30 seconds?

Just trowing in a few ideas. Should be possible but the "time window" will be pretty tigh and coordination need to be very good.

A professional editing tool will probably help a lot in post production.

In my old non- or semi professional Adobe Premiere there is a 24 fps project setting. This should (I am pretty sure) allow to capture and edit the film at true 24fps and and finish the film for playback at 25 fps without any conflicts.


R

[Lucas Lightfeat]

Why 15 cameras? Does this director actualy have a clue what he is doing, or is this just inexperienced experimentation, which it sounds like. Unless there is a specific intention you haven't yet explained for the cams, it's a stupid idea, IMHO.

If one cam is sync., this can be used as reference, but if there is an edit every 6 or 7 seconds (a very long time) you won't need sync at all, as you can stretch anything by duplicating/erasing frames if you're pushed into a corner during the edit.

16mm cameras, such as Arri BLs are deadly accurate fps, even without a crystal, as are Canon 1014XLs, Nizo 6080s and some other 16mm cameras. Noisy cameras aren't a problem, of course.

Why 15 cameras? Most of them might be in shot at any time - is this the idea?

Curiously
Lucas

[Lucas Lightfeat]

With Kodachrome, my Nizo 6080 will keep 100% sync for a whole roll with the crystal from the film group...crystal sync works - you'd hope so for the price! I have a 25fps crystal, so no experience with pulldown, I'm afraid.

Sorry - it's not necessarily a crap idea to shoot with 15 cams for the whole roll - it all depends, of course, what you're filming.

I've shot with non synced cameras for sync sound - a lot actually, and it didn't work well with a Canon 518SV autozoom, a medium priced S8 cam. It was stableish, so could be made to work by dividing the clips into 6 or 7 second sections and, but shot at about 22 - 23 fps.

Good luck

Lucas

[mathis]

hi andreas,

He will therefore shoot at 24fps and will do post sync on a computer. I will transfer the films and convert them to 25fps.
- My question is: What is the best way to transform 24fps into 25fps? (Digivid, Will Dodcap be my best choice?)

i would definetly *not* convert the 24 fps electronically to 25 fps.
i would recommend the following (assuming they´re performing to playback):

slow down the playback by 4,166666666667 percent, then you get 24fps for the playback. shoot on 24fps and telecine frame by frame 25fps.
sync to the original playback and come home to 25fps.

if they´re performing live it makes things more difficult. 4% is almost a halfstep tone.
try to let them play in the key a halfstep lower.
b.t.w.: speeding up a voice is less noticable than slowing down.


doesn´t so much cameras hinder creative lighting? i mean, everytime there´s a camera or a shadow in the lightings way...

much success!
- m

[Andreas Wideroe]

Why 15 cameras? Does this director actualy have a clue what he is doing, or is this just inexperienced experimentation, which it sounds like. Unless there is a specific intention you haven't yet explained for the cams, it's a stupid idea, IMHO.

Yes he knows what he is doing. He's actually one of the leading music video cinematographers in Norway and he's going to make a very special video with this. All I know; 360 degrees filming, cutting one or few frames from each camera, make the whole thing move around the group. Atleast that's the impression I got. Nevertheless, it doesn't matter how he's going to use it, the thing I was wondering was the sync stuff and I got some fairly good answers here. Thanks guys. If anyone wants to comment or suggest other things, please post.

Cheers!

[Lucas Lightfeat]

Ahaaaa...I suspected that this was the idea, but it seemed strange to use film cameras to do it. I love this technique, and I retract my comment about it being stupid - it's.....Bold!

I always thought that they used stills cameras to do this, triggered to go off simultaneously. It's used to great effect on a lot of adverts, and at the end of the film Buffalo 66. I want to do this one day, but with a film camera on either end of a line of stills cameras, electronicaly triggered to click simultaneously. This would allow more consistent results, I think, as the cameras could be identical, and so yield consistent results.

I suggest that you have the best cameras, crystal synced, on both ends of the line of cameras, and so the ones in the line needn't be used crystal, as you'll just be taking a single frame from each one, if I understand what you're planning correctly...

Again, apologies for the earlier comments. I imagined some crazyness with millions of handheld cameras whirring away for 2 1/2 minutes whilst the band pouted and strutted their stuff....

Lucas

[Cranium]

I didn't get the impression that the "bullet time" effect is the goal here.
If it is, you'll never be able to pull it off effectively with a bunch of random, wild-sync'd cameras without LOADS of post work.
But again, I don't get the impression that that's the goal.

[digvid]

Andreas -

By no stretch of the imagination am I an expert on sync sound, so I will have to defer to other people on the forum as to what the "best" methods to use.

However, in the event that you do decide to convert from 24 fps to 25, you can certainly do that, either in Dodcap or Premiere.

In Dodcap, you would have to override the 24 fps on PAL Video option with a custom pattern (see the appendix of the Dodcap help file). You can override both the whole-frame and interpolated patterns if you wish. If you overrode the interpolated pattern, you would add something like this to your Config.ini file:

B_24_PAL=222222222222222222222233 ...or...
B_24_PAL=322222222222322222222222 ...or...
B_24_PAL=332222222222222222222222 ...etc

For whole frame, you would add something like:

W_24_PAL=422222222222222222222222

I think all of these would add the extra frame to pad 24 to exactly 25.

I have read a little on the web about sync sound in PAL, and it really is not such a simple issue. I was reading one article that said there are generally two methods of doing it:

A) Just running the 24 fps footage at 25 fps instead and doing a pitch adjustment on the audio track to lengthen it to 25 fps.

B) Pad the video stream out to 25 fps using one of the patterns I mentioned above and then synching to the audio.

Let us know what you decide to do!

- Jeff Dodson

[mathis]

motion won´t be constant duplicating one frame! you´ll see it.

[Guest]

If your cameras are not crystal synched, then I would not even worry about the conversion of 24 to 25 as it is quite possible (and quite probable, actually) that one or more of your cameras will be running at 25fps at the beginning of the take and as slow as 23 or 24 at the end of the take, depending on film drag, batteries, etc. In short, the conversion of 24-25fps will be the LEAST of your overall problems. By the time the cameras get even half way into the shot, they'all all be out of synch and finding matching frames will be a nightmare. I like the idea but not sure it's really worth it.

Here's an alternative. Why not put all the cameras on single frame and fire them with a single rotary actuator in sequence? The actuator could be run so that the cameras are, indeed, taking single frames (one after the other) at a "rate" of 25fps. To be clear, each camera is NOT running at 25fps nor is it taking single frames at 25fps. Rather, one camera takes a frame, then the next camera takes a frame a 25th of a second later, then the next and so on at a rate of 25 single frames per second. A very simple rotary actuator using microswitches could fire the cameras (assuming they all have electronic shutters) and the rotor could be driven by an AC synchronous motor that ensures constant speed. Even if the over all synch gets off a bit, the cameras will all be in step with each other. You'd all use a LOT less film for the same effect.

Roger