This IS the Avid L2: Re: [Avid-L2] How to convert a file containing 18fps 8mm film frames to 24fps?

Wednesday, December 16, 2015

Re: [Avid-L2] How to convert a file containing 18fps 8mm film frames to 24fps?

If your file is 29.97p and you want it to play back as 18p in a 23.976p sequence, then I would try this:

Open a 23.976p project in MC

Link the 29.97p file

Cut into a sequence

Promote its motion adapter

Choose source = progressive, output = progressive

Choose Duplicated Field

Change speed to 59.5% (I think that math is OK)

It should play back at the right speed, and MAYBE add the pulldown you want.

Otherwise, I would output the image sequence and deal with it that way.

On Wed, Dec 16, 2015 at 4:10 AM, Steve Mullen dvcinlv@gmail.com [Avid-L2] <Avid-L2@yahoogroups.com> wrote:

> Otherwise, I bet Media Encoder or Compressor (using Frame Controls - Fast retime) would handle this accurately.

Mark, I laid out your solution:

Rate Control: FAST (nearest frame) <<< I assume this "Fast Retime"
Set Duration * so source frames play at 24.00 fps

Each second 24 frames need to be placed in the new file. The "nearest" 18fps frame -- closest in time to when a 24fps frame would be output -- will chosen to be output. This works as one frame in every three is repeated: 1:2:1

Frame: 1 2 3 4 1 2 3 4 1
24fps: 0.000 0.042 0.084 0.126 0.168   0.210 0.252 0.294 0.336

0.0   0.014 0.028  0.028 0.014 0.0 0.014       0.028 0.028 0.014   0.0

18fps: 0.000   0.056 >>> 0.056 0.112 0.168 0.224 >>> 0.224 0.280   0.336

Then I realized I made an error when I said the first file was 18fps. My frame-by-frame film transfer unit's software outputs a file with every film frame recorded as one PsF video frame. Unfortunately, the software tags this file as 29.97fps because, I assume, a QT file needs some frame rate tag and 29.97 is the only valid NTSC frame-rate. So the times aren't every 0.056 as I showed, but 0.033. (I think this is why MC won't work either.)

Your solution would work were there a way to change the source file's frame rate to 18fps without changing any frames in the file. I have utilities that read-out frame rate, but at this minute I can't think of one that modifies a frame rate. Anyone?

I could convert the source file to a folder of numbered images. This eliminates all frame rate information. I could write an AppleScript that copies each image to another folder with every third image copied twice. Now Compressor would output a 24fps file from the second folder of images.

Far simpler would be if an existing utility could be given a string = CCR and it would use this pulldown to make a file and tag it 24fps.