Tuesday, October 9, 2012

Video Synchronization, Logic Pro and the "Tempo Change Trick"

Years ago, trying to synchronize your audio workstation to video required video-tape machines, a SMPTE reader, midi machine control, and the patience of Job when everything inevitably went horribly wrong.

Today, all you need is your sequencer and a QuickTime movie - but that still doesn't mean there aren't some technical issues to address and overcome - especially in Logic Pro.

In this posting I am going to outline the most basic ways to deal with Logic Pro and synchronization to a feature film, specifically by using tempo changes as anchors.

First: Determine the video frame rates, sample rates, and movie start.

To do this you will need QuickTime Pro.  QuickTime Pro is the best investment ever and for many of the things I will say in this blog, you will need to have that upgrade.  You can get it here:

Once you have purchased QuickTime Pro, open the video to be scored and go to the inspector window ("Command I" key command).  You should see something like this: 

This is the inspector window from a movie I scored recently entitled The Occupants (aka "Blood Relative").

The important characteristics to note are the sample rate (48.000 KHZ) and the FPS (23.98 "Frames Per Second").

Now that we know this, open your logic session and goto: File / Project Settings / Synchronization:

The following window will open (Keep note of how you got here as you will need this window again soon).

In the window above, I have already selected the correct frame rate of 23.976 FPS (as close as we get to 23.98).

Next, we goto:  Project Settings / Audio, by clicking on the button that says "Audio."  In this case, I have selected the sample rate of 48.000, to match the movie.

Finally, click on the Project Settings / Video button on the right.

We need to edit the movie start time (currently set to 00:00:00:00) in this window to match the movie's actual start time.  To determine the movie starting frame number, open the move and goto the first frame.  In this case, the first frame of the movie is 00:59:58:00 - exactly two seconds before the beginning of picture (If there is no SMPTE number, just use 1:00:00:00:00).

We edit the video project setting to match.

Pitfall number one to avoid:  Logic does not like negative measure numbers and as a matter of fact, can not "think" earlier than measure negative 9 !  If you have too much pre-role before the start of the music, you will have synchronization problems, specifically when importing audio from the movie (I will create a specific blog entry just to address this later).

This start time of two seconds before picture is not chosen at random.  Given the option, you should choose this number as it helps you avoid a few this inherent problem of synchronizing in Logic.  In this case, I personally used QuickTime Pro's editing feature to trim the beginning of the video to match this frame number - the original start was 30 seconds earlier.

Once these settings are all correct, we are ready to open the movie and add it to the session.  In Logic 9, you find this command here:  File / Open Movie.  In earlier versions, this window is found under "Options."

Open the movie.  The movie should scroll properly with your Logic session counter and stay in sync - within the statistical rounding error of one frame - wherever you locate to.

Next we have to determine where the music will actually start, and how we want to organize our cues within the score.  There are two main ways of doing this, both of which have their positive and negative aspects.

Method 1:  Multiple cues in one session

Method 2:  One session per cue

I will adress both of these methods in a future blog, but for now, let's assume for the sake of instruction, that you are only creating one cue, and that cue starts at 01:05:00:31:20.  This is where we want measure one to occur.  There are two ways to do this.  

First is to go back to our synchronization window and tell Logic that "Bar Position plays at 01:05:31:20.00, as I have done below.

Once this number is selected, as you can see in the window below, all the counters should match up; Measure 1 occurs as dictated.

The Tempo Change Trick:

As an alternative, I recommend using the tempo window to synchronize your video, which opens up a whole host of synchronization features that I have not seen cataloged anywhere.

Here's the secret:  Tempo changes in Logic are really "anchors in time" relative to the movie.  You can use them to move the sequence around.

As in this instance, instead of using the synchronization settings window, once we have properly imported the movie, we can set the cue start by opening the tempo window and typing in our desired starting point into the tempo change at measure 1.  This anchors the entire sequence to that frame number, relative to the stationary movie.

Here is where this process of using the tempo window for synchronization really shows it's value - when you are trying to hit a specific moment in the action on a specific beat.   

As in the picture below, we see the cut to the front gate of the mansion occurs at 01:05:40:12.  Looking at the counter in Logic, we see at our tempo of 120 BPM, this moment occurs just before the downbeat of measure 6, i.e.,

Musically, we really want the cut to occur at exactly measure 6.  Using this concept of tempo changes as anchors, here is how we make this happen.

First, in the tempo window, we create a tempo change at the downbeat of measure 6.

We then change the location of measure 6 by manually entering our desired frame 01:05:40:19.

After the desired frame number is entered, you will notice that Logic has automatically changed the tempo in measure one from 120 to 120.2315, to place measure 6 at the exact desired moment.

Yes, I know there is another, much more complicated window you can use to do the same thing, "The Tempo Operations" window (below), but in my experience I have found it cumbersome and not as accurate as using tempo changes.  I avoid this window whenever possible.

I will be getting much deeper into video synchronization using tempo changes in a future blog, in the meantime, I trust what I have shared here will get you started.

Like this post?  Check out some of my other music tech posts:

Buy Logic Pro X at they Apple Store:


  1. I literally just found this blog, and must say it was more helpful than anything I found online! Thank you so much for sharing this, even if its a little old :)

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  3. thanks, really useful - i needed to shift the whole cue half a second earlier, but maintain the bars n beats, made the new tempo event a bar before my first bar, & half a second adjustment. Now it's bang on :) and my brain is not exploding! bonus!!