Having trouble running my software on MacOS Mojave or later? After many years of distributing my software for free, Apple's recent software policies have made it difficult or impossible for me to continue. Independent developers like myself are now required to pay Apple each year and have our software approved by Apple, otherwise our apps will be tagged as dangerous or "damaged" and can't be opened. For the foreseeable future I can't invest the time and money to fix these problems, but you may be able to work around it by right-clicking the app and selecting "Open" or using the method described on OSXDaily.

Film-O-Sync Guide

This guide is the instruction manual for my film-projection audio software, Film-O-Sync.
(Click the link for screenshots, features, and latest download.)

Edit on Film

This whole process is based on film-projection, so you need to finish on film. (I usually transfer all of my footage to video and make my initial edits on the computer. Then I match back to film on the Steenbeck.)


The software does not know when your sound should begin, so you need to add leader so YOU can press a button to start the sound. You can get “Academy Leader” from Motion Picture Enterprises on 45th ST in NYC (212) 245-0965 or Christy’s Editorial in Burbank, CA. You can also draw your own if you are so inclined, or cut it from some old found-footage.

Transfer to Video

You need to transfer your film to video so you can cut your audio digitally. A well-maintained Steenbeck runs at exactly 24fps, as do some DIY transfer machines. Professional telecine transfers run at exactly 23.98fps. (You will need to know which speed when you project your film.) Make sure you transfer the whole thing, including the leader, and remember that your picture is now “locked” so if you make changes to your picture it will no longer match your sound.

Add Sync Beeps

It is crucial to insert an audible reference that is aligned with your picture. Traditionally there is a 1-frame “beep” on the frame where the 2 appears in the countdown. I recommend adding earlier beeps so that you can check your sync before the “2-pop” arrives: Add a beep on the 5, 4, 3, and the 2.

Mix and Prepare

In your editing software, export or “bounce” to a file with these characteristics:

  • AIFF, 16bit, 48kHz, stereo (called “stereo interleaved” in Pro Tools)
  • Mono is fine too, if your soundtrack is mono.

It is crucial that the file begins with your first sync beep, with no silence in front of it.
During projection you will be hitting a button, triggering your sound. That first beep is what you want to hear under your finger like a piano key. Any delay will make your sound late.

Prepare Computer and Projector

Note that Film-O-Sync requires a simple modification to your projector, so I made an instructable to describe the process. (Here is a PDF version.) I used an Elmo 16-CL but most projectors will be similar.

• Copy your AIFF to the computer.
• Make sure there is a cable connecting the “Tachometer” plug on the projector to the computer.
• Go to Apple menu / System Preferences… / Hardware category / Sound
Make sure that the proper sound input is selected.
Run the projector and observe the meter. (film does not need to be loaded) On some Macs you must drag the “Input volume” slider all the way up (even if it already is!) due to an Apple problem with the sound-settings. You want most of the meter to light up, not just a few bars.

Launch Film-O-Sync

  1. Choose Your File
  2. What frame-rate does it sync with?
  3. Run the Projector. You should see the frame-rate displayed
  4. Thread your film and start the projector. Press the space-bar when your first sync mark arrives.
  5. If your sound is late or early, press the < & > arrow keys to nudge it earlier & later. If you stop and start the projector, the sync will be off by a few frames!
  6. Enjoy synchronized digital sound for your film!