Sound Out Of Sync

Viewing 4 reply threads
  • Author
    Posts
    • #91564
      AvatarShaun Dowey
      Member

      Hi

      Normally I record sound direct into the camera but recently decided to try something different. I recorded the footage through a Canon 700D and I set up a microphone through a Zoom H4N to record the sound.

      However, now that I’ve come to edit the footage (using Final Cut Pro X) the footage seems to be faster than the sound and very quickly goes out of sync.

      Does anyone know what I’m doing wrong?

      Cheers

      Shaun

    • #214778
      Avatarmcrockett
      Member

      Hi Shaun,
      I’m sorry to hear that you’re having this problem. Actually, it’s not that you’re doing anything wrong; this is just the nature of audio and video. Our cameras record video in frames, and they record and sync up the audio as they record the video. However, audio recorders record audio in Hz, and trying to match that up with frames is often difficult, especially with long clips. The longer the clip, the more time the audio has to get out of sync.

      There is a solution, however. Red Giant makes an application/plugin called PluralEyes. PluralEyes can sync up your video and audio automatically, and the current version can take measures to correct the issues that cause video and audio to lose sync over time. It is compatible with Final Cut Pro X 10.2.3 and higher. Go to http://www.redgiant.com/products/pluraleyes/ and check it out. They’ll give you a free trial.

      Hope this helps.

    • #214781
      Avatarpaulears
      Participant

      Eh? Audio recorders record in Hz? Nothing records in Hz! Hz is simply a unit of frequency. Almost certainly the problem here is the recording format. Video formats are frame based, so there are differences between them – 24/25/30/50/60 etc. It gets a bit confusing, but your zoom recorder is not frame based – it simply records at a sample rate – X numbers of audio samples every second. Normally 44,100 or 48,000 a second. Bringing in an audio file a different sample rate to the video audio usually creates a pretty obvious frequency shift, and a change in the running time. This makes sync go out very quickly. It also sounds a bit mickey mouse too. The usual sync issues in the timeline come from the video format being mismanaged – but here we shouldn’t really have a problem with one video track and one audio track. Plural eyes works pretty well, once you are certain what is causing the problem, and if it’s a proper problem plural eyes might fail.

      I think what I would do is set up a test recording with the zoom and the Canon. Have you got a clock with second hand that ticks? Record five minutes of the clock and five minutes of it ticking on the camera audio track. Record 5 minutes of the speaking clock on the zoom.

      Once you have them synced up, you should be able to watch and listen and see where the slippage is happening. while playing back you also have your own watch to double check the

      Put them both on the timeline, and sync up manually the tracks and see if they drift. If a frame or two gets dropped in the picture – you’ll see a jerk in the hand movement. If you suspect that the audio may be being played back at the wrong sample rate, record a tone on the camera and the zoom and check they replay the same. It’s feasible that all you have is a mismatch somewhere your editing software is attempting to fix. Premier seems very happy to have a mix of 25 and 30fps material on the timeline – but does cause audio sync issues if you don’t spot it. You just need to experiment and track it down.

      Auto fix with software often works on speech, but fails on sources with music – it can slow down and speed up the audio without changing it’s pitch – but doing it often produces unwanted artefacts – so there’s no perfect solution.

    • #214785
      Avatarmcrockett
      Member

      Paulears,
      Thanks for setting me straight. I did kind of type my message in a hurry. Now that I look back at it, I wonder what I was thinking when I worded it that way. My mind was all over the place.
      But yes, you articulated the point better, that video is frame based, while the audio recorder is not recording that way.
      Shaun, just listen to Paul on this. πŸ˜‰

    • #214794
      Avatarpaulears
      Participant

      ironically – I’ve just been editing some multi-camera stuff and a small but of footage I borrowed from a person at the event who I noticed had an iPad – it goes out of sync badly – just 30 seconds of it’s media into the project is badly out by the end. The frame rate I can normally deal with, but it seems to be quite ‘loose’, timing wise. Tricky to use, but got there with effort.

Viewing 4 reply threads
  • You must be logged in to reply to this topic.

Best Products

homicide-bootstrap