Film File Sizes - why is one bigger than the other?

Pupose: Sometimes customers ask why one file size is bigger than the other with regards to film transfer file sizes and different fps.  Here's an answer/explanation that may help.

Answer:

As for the file size, that all has to do with the fps and the corresponding pull-down that is applied to the file based on the fps selected.  Basically, standard video is at 30fps (29.97) and this is the file that we are seeing.  Now depending on the fps selected, the video will have multiples of the film frame in the final file.  For example, if the file is processed at 10fps there will be 3 copies of each frame, if at 15fps there will be 2 copies of each frame, and at 30fps there will only be one copy of each frame.  16fps, 18fps, and 24fps do not evenly go into 30fps so they will be further complicated by adding pull-down frames to pad them to 30fps.  Therefore, in summary, a 16fps speed file will be larger than a 24P file just due to the number of frames.

I hope that I’ve explained it clearly enough….I know it took me a while to understand it at first.

Reference:

Further info can be found in a document:  User Data\TMM\Research\16mm transfer units\Film Transfer process.docx

What to do when a film was pulldown at the wrong speed

If you are doing editing on a film and you notice that things are moving too fast or too slow, you will need to figure out the correct frame-rate and fix it. For the most part, film is recorded at standard speeds, but there are always odd-balls because older film cameras can do whacky things.

Step One: Do The Math

Look at how many frames per second (fps) your film is currently being played at, and then speed up or slow down your film to figure out the true speed.  The best case scenario is if you have access to the computer that did the pulldown, you can use it's program to preview the film at different fps speeds!  Once you know the new speed, use this simple equation:

New FPS / Old FPS = Playback Rate

And you take this rate, and simply right click on the event in Vegas and change the Playback Rate setting to this number.

Step Two: Stretch the Event

Once you've set the playback rate different, you'll need to stretch the event on the timeline longer so that you aren't clipping the end of it.

Step Three: Open MyFilms

Go to www.film2hd.com/myfilm/ and login with the admin password.  Go to the tab "Manage Films".

Step Four: Find the Film

Sort by Client ID, and your film is likely near the top.  You can scroll down and find the film by it's relative ID, which matches the filename's ID from the timeline.  Else sort by whatever is more relevant and find it.

Step Five: Change Values

There are two parts that need to be updated in the MyFilms database: Duration & FPS.  You should already know the fps, but if you only guestimated by stretching the clip, reverse your math to figure it out:

Playback Rate x Old FPS = Approximate New FPS

Of course, it's very doubtful that you got it perfect, so round it off to a real FPS count (12, 15, 16, 18, 20, 24, 30). For the duration, enter the exact number of seconds that the new clip is at.