Videomaker – Learn video production and editing, camera reviews › Forums › Technique › Sound › Sound Out Of Sync › Eh? Audio recorders record in
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.