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

Wednesday, December 16, 2015

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

Cinema Tools works but the OP wants 18 fps, and Cinema Tools is limited to 23.976, 24, 25, and 29.97.

On Wed, Dec 16, 2015 at 5:30 PM, bigfish@pacbell.net [Avid-L2] <Avid-L2@yahoogroups.com> wrote:

Cinema tools will restamp a frame rate it it's an I frame codec. Also QT change has some of that functionality but I believe there are caveats to QT changes frame rate restamping that isn't recognized by all software. I haven't used the function in QT Change so I may be in error about it capabilities and limitations. If there was only an expert on it on this list then my Holidays would be complete. Oh wait..... ;-)

---In avid-l2@yahoogroups.com, <dvcinlv@...> 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.