6 Replies Latest reply: Dec 28, 2012 6:53 PM by themessenger82
themessenger82 Level 1 Level 1

I created a video of myself on my iMac using iMovie.  I used the iMac's internal camera and mic.  About a 1/4 through the video (it's about 15 minutes long), the audio starts getting out of sync.  I looked up solutions to this problem, and everywhere I read said to detach the audio from the clip(s).  I did that, and it was still out of sync.  I then tried to split my long 15 minute clip into multiple clips, and then I detatched the audio from each one of them.  Also didn't work.  I tried uploading to Youtube, and Youtube recognized the issue and gave me a series of steps to fix it.  Did it all, and still the audio is out of sync.  This is a simple, unedited video that should have taken me no more than 10 to throw together.  Instead, I've been screwing around with this for several hours.  Does anyone have any suggestions?  Thanks!

iMac (27-inch Mid 2011), Mac OS X (10.7.5)
  • AppleMan1958 Level 7 Level 7

    Can you right-click on one of your Event clips and choose OPEN IN FINDER. In the Finder, right click on the clip and choose OPEN WITH.../QUICKTIME PLAYER. In QuickTIme Player, hold down the Command Key while typing the letter i. This will open the QuickTime Inspector. Tell us the dimensions of your clip along with everything that is listed next to the word FORMAT:

  • themessenger82 Level 1 Level 1

    Thanks for your reply.  This is what I've got:


    Format: Photo - JPEG 1280x720; Linear PCM, 24 bit little-endian signed integer, 44100 Hz, Stereo (L R)


    Thanks again.

  • AppleMan1958 Level 7 Level 7

    Does the QuickTime Inspector give a frame rate? (like 30fps, 24fps, etc.)

  • themessenger82 Level 1 Level 1

    Yes.  And while I'm at it, I'll just give you all the information (minus format and source) in the inspector:


    FPS: 14.89

    Data Size: 1.3 GB

    Data Rate: 12.63 Mbit/s

    Current Size: 1,280 x 720 pixels (Actual)

  • AppleMan1958 Level 7 Level 7

    44100 Hz is fine and the audio codec is fine. Most camcorders record at 48000 Hz, but audio CDs are recorded are 44100 Hz, and iMovie handles them well.


    However, your video frame rate is an odd number. A camcorder in the US will usually record at 29.97 frames per second. In Europe, the standard is 25 fps. On some cameras, you also have the option of 24 fps (same as a Hollywood movie).


    Your camera is recording at 14.89, which is about half of the 29.97 standard. I am guessing that the video is from a webcam or maybe a cell phone or still camera.  It is difficult to sync audio over long periods of time if your video is not conforming to the standards. Cameras like this may record at varioable rates, so sometimes you get more than 14.89 and sometimes less. Your best bet would be to make an iMovie project at 29.97 fps, so that it will basically repeat each frame of your video twice to get up to 29.78 fps. Even so, it will drift out of sync over time.


    If you had Final Cut Pro X, you could use the tools in FCP to conform your video and audio to a 29.97 timeline and probably keep it synced better. Long term, your best bet is to use a camcorder that can shoot 29.97 (or 30) fps.


    Short term, I would suggest keeping your clips in your project short. For your 15 minute clip, drag in the first minute, then the 2nd minute, etc. untill you have it all. Even so, it may drift. Detaching audio is probably not necessary.

  • themessenger82 Level 1 Level 1

    Your short term solution is exactly what I originally tried, and it was still out of sync.  The camera I used is the camera on the iMac.  In the future, should I not use the iMac's cam?  I would hope and think they'ed include a camera that would be capable of recording a simple video of me talking.