Video recorded with built-in web-cam out of sync?

Discussion in 'Digital Video' started by mortenjensen, Aug 19, 2012.

  1. mortenjensen macrumors regular

    Joined:
    Mar 19, 2012
    #1
    Hi all
    I am experiencing a frustrating problem with my MBP-2012 (new version): When I record video with the built-in web cam, there often/almost every time a sound-delay. Some times as much as one second.

    I happens both when I use iMovie and Photo Booth.

    Is this a known problem?

    Morten
     
  2. treatment macrumors member

    Joined:
    Aug 7, 2012
    #2
    Are you talking about latency, or are you talking about sync?

    If you are recording the video and watching it at the same time, than yes of course you are going to experience latency.
    There is no way around that using a webcam.

    IF you are talking about sync, meaning, after the video is recorded, than the frame rate, and the audio sampling rate are not in sync, and that needs to be changed in the camera's preferences, which should be an easy fix.
     
  3. mortenjensen thread starter macrumors regular

    Joined:
    Mar 19, 2012
    #3
    Great, it is not latency.
    The sync problem is experienced in the final exported file.

    How do I adjust the web cam's settings? Which settings should I use?

    Morten
     
  4. treatment macrumors member

    Joined:
    Aug 7, 2012
    #4
    About the webcam....read the manual.

    When you export the file, make sure the audio settings and codec settings are correct to what the camera is natively shooting at.

    For example:
    If the camera records at 44.1 kHz, make sure you don;t accidentally export it at 48 kHz. This would equal out of sync.

    If the frame rate is natively 15 FPS, don't export it at 29.97 FPS.

    FPS= Frames per second
    Treatment
     
  5. mortenjensen thread starter macrumors regular

    Joined:
    Mar 19, 2012
    #5
    Hi, thanks for the reply.

    Now - we are talking about the built-in FaceTime web-camera. As far as I can tell,
    - there is no manual
    - there is no place to set these settings.

    Here is what I do:
    - I record video either natively within iMovie or with PhotoBooth.
    - I edit it in iMovie.
    - there is a sync problem.

    It occurs already when I record within PhotoBooth - so it can't be conflicting settings with iMovie.

    Is there another place where you can adjust the FaceTime-camera for all programs? I have been unable to locate it.

    Morten
     
  6. treatment macrumors member

    Joined:
    Aug 7, 2012
    #6
    Ok, first of all, I don't use iMovie (anymore) although I had a look, and it seems to allow NTSC-30 FPS settings and PAL 25 FPS.
    (Interesting the idea of using Photobooth, it never occurred to me!)

    Here is what I would recommend instead:

    If you are working with video, you absolutely NEED to have QuicktimePro, and if you don't, it's dirt cheap.

    In QTPro, select FILE-New Movie recording.
    In QT preferences, you can choose: Good, Better, Best, and Device Native.
    Device Native is what you want for the highest quality.

    Funny, I experimented just now with all available settings, and found sync issues with ALL of the settings.


    I checked the AudioMidi settings, and my audio rate is 48Khz, which is in line with the "Device Native" setting in QT.

    So in short...I am just as stumped as you are!

    I can only conclude that using the built in camera for these kind of purposes is clearly the wrong tool. Great for SKYPE, not so great for anything else.
    However, the sync issue could be solved by hand, in iMovie, by simply dragging the audio left or right on the timeline until it appears to be in sync. You could use a clapper, or do what I did, and clap my hands in front of the camera before and after the performance take.

    The sync might drift on a longer video clip, let me know how it goes.
    9 times out of 10 though, sync problems are usually due to the audio being recorded at 44.1, instead of 48kHz, or, at 24 bits instead of 16 bits.

    My suggestion is that you find yourself a proper video camera instead.
    There are so many things available....in car cameras, portable Flash memory cameras, even the camera on your smart phone. The only downside, is that inevitably you will have to transcode your files first, before bringing them into iMovie.

    On my last journey to Thailand, I video blogged every day of the journey and uploaded it to Youtube. I used a cheap Nokia phone, the built in i-Sight, and also a MINIDV camera.
    I had sync issues, I had aspect ratio problems up the yin-yang.
    Luckily, I also had Final Cut Pro at my disposal, so I could fix these issues.
    The camera that was reliable, and required no transcoding, was the MiniDV cam.
    It shoots at 29.97 FPS, NTSC, audio 48Khz, which iMovie was designed to accommodate in the first place.

    Good luck!
    Treatment
     
  7. mortenjensen thread starter macrumors regular

    Joined:
    Mar 19, 2012
    #7
    Great info here, thanks.

    Just a few things:

    - Yes, the sync drifts in long videos. In the end it always goes back into sync.
    - I think the kHz-suggestion is spot on. The thing is just: Where do I change the settings for the FaceTime camera?

    I know another solution would be to buy another cam - but I am getting stubborn here :) - we are talking about a simple operation using only mac-soft- and hardware.

    It should work!!!

    Would anyone know if this is a known problem - or a fault on my system?

    Morten
     
  8. treatment macrumors member

    Joined:
    Aug 7, 2012
    #8
    I would suggest you log in to apple.com and ask there.
    Much wider user base, and audience.

    Good luck!
     

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