Slow Motion Video with the Canon 7D (or 5D Mk II) for FREE.

Slow motion video from the new DSLRs like the Canon 7D and the Canon 5D MkII is possible using the cameras' 60fps mode to capture and then playing it back at either 24fps (film speed) or 30fps.

The problem for me, though, was find an inexpensive and simple way to do that conversion on my Mac. If possible, I didn't want to have to use After Effects or Final Cut Pro to do it. Unfortunately, nearly all the ways I found on the web involved use of these high-end apps...until I came across QT Sync.

QT Sync does a lot of other cool things with Quicktime .MOV files (the Canon 7D and 5D MkII write .MOV files with the H.264 video codec to encode the video stream). But I was interested in the fact that it can losslessly adjust the frame rate of a video clip. And doing so is trivially easy.

Here's a simple how-to on using QT Sync to convert that cool 60fps video you've captured into a high-quality, high-definition slow-mo clip ready for in you editing apps:

• 1) Download QT Sync from their website: qtsync.com and install the app.

• 2) Launch QT Sync and click "Open..." from the File menu to open your video to process.

• 3) With the video opened, click "Change Movie Playback Speed..." from the Edit menu.

• 4) From the dialog box that pops up, choose the new frame rate from the pop-op menu or type in a custom frame rate as desired and click "OK." Note that QT Sync does not do anything with/to the actual frames, it just changes the way other apps will see the frame rate. Hence, no loss in quality.

• 5) Save your newly modified file as a self-contained movie.

That's it! Feel free to import the newly saved file into your favorite editor and it'll see it as though it were to be played back at the new rate. For a conversion of 60 frames per second to 24 fps, the clip is now running 2.5x slower (40% speed). For 30fps, it's now 2x slower (half speed). That's nice slow-motion without frame blending...all thanks to the cool Canon 7D and 5D MkII cameras and a little Mac OS X app. 

Here's an example. It's not a particularly spectacular video (from my son's pinewood derby districts), but it shows the idea (60fps --> 24fps):

Best of all, QT Sync is free.

Sure, for even more advanced slow-mo, there's always software like the Twixtor plug-in for Final Cut Pro or After Effects, and if you want that level of control you probably don't need this tip. But for those searching the web as I was for a quick-n-dirty solution, hopefully this will help.

--DCP

[Note: At the time of this post, I was using QT Sync v.0.3.3 on Mac OS X Snow Leopard 10.6.3 with no problems.]

UPDATE:

There's a problem with the above solution if you want to use the clip with Final Cut Pro. Even when run through the process above, when the clip is imported into FCP, the clip plays back as the original 60fps video.

So I've found an even more direct (and also free) solution: Apple's own Dumpster.app. Dumpster for Macintosh is a little app for editing Quicktime movie headers. Specifically, we can edit the headers to losslessly change the clip to a 24fps clip that will be recognized as such in Final Cut Pro.

Here's a step-by-step solution:

• Download and launch Dumpster from Apple's developer website.
• From Dumpster's File menu, open your movie clip from the 7D.
• On the screen that appears, click on the "mvhd" field. The values we want to change here are 'preferredRate', 'timeScale', and 'duration'. Converting from 60fps to 24 fps, the values should be 2.5 for the preferredRate (2.5x slower), the timeScale should be changed from 60000 to 24000 (for 24fps), and the duration should be 2.5 times the current duration. In this example, my clip was 524524 so 2.5 x 524524 = 1311310, which is the new duration.
• Now click on "mdhd" under the first "trak" field.
• Again, change the timeScale from 60000 to 24000, and change duration to 2.5 times the current duration (e.g., 524524 becomes 1311310)
• Example result:
  
  
  
  
• Now "Save" the file. 
• Voila! A file that will work in Final Cut Pro, too.