Mixing Frame Rates in Timeline

Posted by apmende 
Mixing Frame Rates in Timeline
March 17, 2010 01:08PM
These 2 frame sizes and frame rates were shot and imported into FCP.

1280 x 720 @ 59.94
1920x1080 @ 29.97

When I insert them into the timeline, it jitters/stutters. Which timeline should I use the 59.94 or the 29.97. I would assume that you would create a HD timeline at 1920x1080 @ 29.97 and conform the other 1280x720 into that timeline. Am I wrong or is there a work-around. What should I do?

1280 x 720 @ 59.94
1920x1080 @ 29.97
Re: Mixing Frame Rates in Timeline
March 17, 2010 01:21PM
First thing to do: Go punch your DP in the face.

Now that that's taken care of, let us consider your problem. I'm going to assume that when you say "1920x1080 @ 29.97" what you mean is 1080i60. That is, interlaced material. That may not necessarily be true, and if it's not, you're gonna need to come back and call me a dummy and let me try this again.

I'm going to tell you what needs to happen, like technically. Then I'm going to tell you what I would do if I were in your shoes. I cannot promise this will work, though, because I've not actually done it myself. I'm just improvising here.

But before I do either of those things, I'll tell you that the easy answer is to find a post house with a hardware standards converter, like a Teranex or an Alchemist. Send them a tape with your 720p60 stuff on it ? that's the "1280 x 720 @ 59.94" material you referred to. HDCAM SR would be best. Or they may accept a Quicktime movie, which might be even easier for you. Have them run that stuff through their box, and give you back 1080i60. Their converter will do the job better and faster than what I'm about to describe.

Now. As to what needs to happen, it's this: You're going to need to scale the 720p60 material up to 1080p60 first. Yes, I know, 1080p60 is not a broadcast format. That's okay, because we're just doing this as an intermediate step. I would try using Compressor for this, creating a custom setting that just scales the footage and that's all. No converting to interlaced, no compressing, no retiming, just scaling it up. I would also do this with a very short snippet first to make sure it works right without having to render all weekend.

The next thing you have to do is to turn that 1080p60 stuff into 1080psf60. That's not a broadcast format either, but what I mean is you want to turn your frames into field pairs. So for each frame, you'll have field one and field two.

Then the last step is easy: You just throw out half those fields. From frame one, discard the lower field. From frame two, discard the upper field. From frame three, discard the lower field, and so on. When you combine the fields you have left over, you'll have proper 1080i60, which is a broadcast format.

I will again try using Compressor for this. Once I have my 1080p60 stuff from step one, I'll run it through Compressor with another custom setting, this time one that does nothing but convert from 1080p60 to 1080i60. Maybe Compressor will be smart enough to do it the right way, discarding every other field and recombining. I really can't say whether it will or not, but it'd be my first try.

Seriously, though. The right answer is to run your stuff through a Teranex or an Alchemist. It'll do precisely what I just described, only in real time and with no actual work on your part.

And take heart. At least the standards-conversion job you have to do is mathematically possible. If you'd been asked to convert 60i to 24p, you'd have no choice but to use motion estimation, and even when that works, it still doesn't really work.

Re: Mixing Frame Rates in Timeline
March 20, 2010 08:15PM
Thank you so much. I'll try to get a friend to convert the footage through a teranex where he works. This seems like the easiest route and it's only about an hours worth of footage.
Sorry, only registered users may post in this forum.

Click here to login


  Web lafcpug.org

Web Hosting by HermosawaveHermosawave Internet

Recycle computers and electronics