Fps And Smpte/time Options

[uvbnskoold]

Hey people,

I didn't find a suitable category for this... if I missed one, please forgive me.

I'm trying to figure something that's sort of baffled me for a while.

If I take a film in any pc format, say wmv, which was shot and given to me in 29.97 fps and I take this and put it into iMovieHD to convert it to a mov file and it eventually compresses it to 12 fps upon export, does that screw up the SMPTE?

In other words, if I write a cue for a scene that is exactly 1 min when the film is in 29.97, will that same cue still fit perfectly if the film is compressed to 12 fps?

I would think (logically) that the time something plays out in, isn't affected by how many frames go by per second (ie a one minute scene still takes one minute no matter what the fps is). Am I correct in this thinking? Or not...

I'm just trying to save myself trying to find an actual working video converter to switch the file from wmv to mov so it will work in Logic (actually just trying to find any excuse not to have to use my PC!). Plus this has been a conundrum for a while which I just haven't had the time to test.

Thanks for any help you peeps can give!

Uvee

[Jim Hoyland]

In principle you're right, a cue at 1 second will play at 1 second regardless of the frame rate of the movie. The main reason being that whilst the video playback is based in fps the audio will be played based on the sample rate which is always much more detailed. (I'm talking in terms of common computer based video wrappers like WMV and MOV here). Thats why it makes no sense to edit audio in a video editing package.

The SMPTE should still be fine though, with the final four digits reflecting the number of frames and sub-frames used to make up 1 sec. In ProTools you would need to set the session to run at 12 fps (tho' I can't remember if the frame rate goes that low) and you may need to check preferences for movie playback in Logic for a frame rate setting.

However, when working with movies in Logic or any other DAW you're going to lose quite a lot of accuracy by dropping from 30 dfps to 12, and as you'll know, the picture quality will be pretty awful, especially with pans or zooms. This may not be too important with music cues, but if you're spotting dialogue or SFX the results will be obvious once the audio gets laid back to the original video file.

If you get the Flip4Mac QuickTime plugin you should be able to run your WMV files without conversion, and if you're in Mac OS 10.4 there's the Perian plug-in which opens up a huge range of file types for QuickTime users. If you do decide to get a video convertor Visual Hub is very good.

This post has been edited by Jim Hoyland: Sun 25 Feb 2007, 13:38

[uvbnskoold]

Thanks for the reply.

I was pretty sure I was right about that part. I'm not concerned about dialogue or SFX, just the music - as that's my job.

My real concern was that I had to get this vid playable in Logic, and logic won't accept the wmv file at all. I was wondering if I converted it to MOV via iMovie (which the only filesize viable would be streaming web which outputs it at 12 fps), and then put it into logic, would my cues still line up in the final film (which will still be at 29.97 fps.

Based on your confimation, they should still line up fine. The only difference would be the amount of frames that go by during that cue... but the time will always stay the same.

Thanks a lot!


Uvee