ajlantern
Level 1 (1 points)

Q: Problem syncing video capture with audio sountrack

Hi,

 

I'm a drummer.  I'm trying to use iMovie to record a video of me drumming to a pre-recorded song.  I want the final video to be me drumming with mixed audio of both my drumming and the original soundtrack.  (Here's an example of someone else doing this on youtube: http://www.youtube.com/watch?v=cgqYkBFSva4)

 

I'm recording the video using iMovie's import from FaceTime (ie. straight from my MacBook Air) and then adding the song that I played along with as an additinal audio track from iTunes, and syncing.

 

This is where I hit a problem, and it's driving me nuts.  When I sync the iTunes song into my iMovie project I use waveform view to line it up so start of the song is perfectly in sync with the start of the video of my drumming.  That works fine.  But then gradually over the course of the video the song track goes out of sync with the video/audio of me playing, and by the end of a 6 minute song there's a very noticable gap, which both looks and sounds terrible.

 

This is very strange since it's the same audio track I was playing along to!  In real-time when recording I was obviously in sync with the music, but then when adding it back to the recording it somehow no longer lines up.

 

Does anybody know why this is happening and how I can resolve it?  Is this a frame-rate issue?

It seems to me this shouldn't be so hard to do what I'm trying to do ...

 

Thanks!

Ari

iMovie '11, OS X Mountain Lion (10.8.1)

Posted on Sep 18, 2012 11:27 AM

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ajlantern

Q: Problem syncing video capture with audio sountrack

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  • by AppleMan1958,

    AppleMan1958 AppleMan1958 Sep 18, 2012 1:21 PM in response to ajlantern
    Level 7 (27,430 points)
    Sep 18, 2012 1:21 PM in response to ajlantern

    My guess is that you are correct in calling it a frame rate issue. The Face Time camera may record in variable frame rates. I would suggest opening the clip in QuickTime Player and checking the frame rate by pressing Command-I to open the Inspector.

     

    For best results, use a camcorder that records at 30fps (25fps in Europe).

     

    One additional thing. Video cameras (but not necessarily FaceTime( will record audio at 48khz, while CDs are recorded at 44.1 khz. That can also lead to a shift, but that is not likely the source of your problem.

  • by ajlantern,

    ajlantern ajlantern Sep 18, 2012 1:42 PM in response to AppleMan1958
    Level 1 (1 points)
    Sep 18, 2012 1:42 PM in response to AppleMan1958

    I opened the FaceTime video in QT. FPS is 14.98 and audio is 44100 Hz.

     

    I tried the same thing using my Sony Bloggie to record the video and then imported the mp4 to iMovie.  Same exact problem with audio/video sync.  The FPS on the bloggie recording was 29.97 and audio 48000 Hz.

     

    Any suggestions on how to make this work in iMovie?

  • by AppleMan1958,

    AppleMan1958 AppleMan1958 Sep 18, 2012 2:04 PM in response to ajlantern
    Level 7 (27,430 points)
    Sep 18, 2012 2:04 PM in response to ajlantern

    Hmmmmm....

     

    One thing to try is to right click on the MP4 clip in your Event and see if it offers to Optimize Media. If it does, this will convert the MP4 to Apple Intermediate Codec, which will be a bigger file, but will not tax your system as much.

     

    Similarly, you could try converting the music track to AIFF. (Especially if it is currently an MP3.)

     

    If that does not work, I would try running it on an iMac or MacBook Pro. These Macs have separate video cards and may give better results.

  • by AppleMan1958,

    AppleMan1958 AppleMan1958 Sep 18, 2012 2:07 PM in response to AppleMan1958
    Level 7 (27,430 points)
    Sep 18, 2012 2:07 PM in response to AppleMan1958

    Here is how to convert to AIFF in iTunes.

     

     

    In iTunes, go to iTunes/Preferences. In the General Tab, click the Import Settings button. Remember how it is currently set, (because you may want to change it back). Choose IMPORT USING: AIFF Encoder.

     

    Now, right-click on the music track in iTunes and select "Create AIFF Version".

     

     

     

    Restart iMovie and import the AIFF version.

  • by ajlantern,

    ajlantern ajlantern Sep 19, 2012 3:03 AM in response to AppleMan1958
    Level 1 (1 points)
    Sep 19, 2012 3:03 AM in response to AppleMan1958

    Thanks for your replies, although no luck yet :-(

     

    I converted the song to AIFF in iTunes and resynced but I still get the lag at the end of the song.  I also tried right clicking on the event and optimizing.  In the version I recorded from FaceTime there was no such option.  In the mp4 version I recorded on my Bloggie there was an option to "Optimize - Large", which I did, but it also didn't help.

     

    I'll see if I can get ahold of a MacBook Pro and try using that like you suggested, although I don't quite follow why it should make a difference?  Why do you think the strength of the hardware (processor speed, better video card, etc) make a difference in whether I'm able to sync the video and audio?  And at which step do you think it will help to use a better computer - when I'm recording the video or trying to sync them after?

     

    Just want to make sure I understand ...

     

    Thanks!

    Ari

  • by ajlantern,

    ajlantern ajlantern Sep 20, 2012 8:34 AM in response to ajlantern
    Level 1 (1 points)
    Sep 20, 2012 8:34 AM in response to ajlantern

    Ok - I've tried all of your recommendations but still no success.  I tried converting the audio files to AIFF, and I repeated the entire process on a MacBook Pro that I borrowed from work - but the video and imported audio still eventually go out of sync.

     

    This is getting frustrating because I don't even know from first principles where the problem is and what I should be looking for. I'm trying all sorts of combinations of factors - frame rate of video, sample rate of audio, strength of computer, etc, but I feel like I'm shooting in the dark.

     

    Can someone help shed some light on this?  Is the problem that I'm using unprofessional video recording hardware (like Bloggie and FaceTime), or is the limiting factor that iMovie isn't pro-level video editing software? Am I going about this whole thing wrong?

     

    Any advice would be greatly appreciated,

    Ari

  • by drewbsn,

    drewbsn drewbsn Feb 27, 2013 12:46 PM in response to ajlantern
    Level 1 (0 points)
    Feb 27, 2013 12:46 PM in response to ajlantern

    Hey Ari,

     

    I was having a similar problem perhaps and this is what I did to fix it.

     

     

    timothymckean

     

     

    Hi All,

     

    I've been dealing with this sync problem tonight as well and here's what I found that worked.

     

    I noticed that the audio sync was fine when I viewed in Quicktime 7, but not in iMovie.  I also noticed there was a small indicator on the clips in iMovie notating that the source clips were in 17 fps, not 30 fps.   This is odd because I recorded the clips using the FaceTime HD camera right into iMovie and it never gave me the option for framerate on the recording.  Viewing the source video in Finder I also realized that the codec for the source was Photo Jpeg... yuck.  Who's choice was that.

     

     

    Using MPEG Streamclip (free video converter) I converted the source video clip to a Quicktime .mov at 30 fps and using the Apple Intermediate Codec and all the audio sync issues were fixed.  Didn't have to optimize, detach, or - most importantly - re-edit anything.    Apple's editing systems love Apple Intermediate Codec (AIC), I don't know why they don't import in this codec by default.

     

    ** Download MPEG Streamclip from http://www.squared5.com/

  • by DiabloNeruda,

    DiabloNeruda DiabloNeruda Sep 7, 2016 3:51 PM in response to ajlantern
    Level 1 (9 points)
    iLife
    Sep 7, 2016 3:51 PM in response to ajlantern

    Been having the same problem making dance videos, and dubbing in the original track from iTunes. Would love to know if this ever got solved by anyone.