Audio and video out sync - delay

Anonymous (not verified)

Hello

I am recording some videos with iMovie HD with Mac's iSight camera. The sound is bad so I am using a H4Zoom microphone for a better sound quality.

The problem comes up when I want to put the two together. I can match them up at the start of the video, but for 1 hr of video there is about 2-5 seconds delay in the end of it.

I tried all sorts of things and its still not yelding.. Been banging my head on the walls.
Tried using FCPX delay audio function and IN the software, it works, I get it right, but the exported file, the final video is still delayed...

Please help

Thank you


Charles Schultz's picture
Last seen: 4 years 5 months ago
Joined: 10/25/2010 - 10:38pm

What frame rate is you camera set at? It sounds like the two are off.


Jack Wolcott's picture
Last seen: 4 hours 20 min ago
Joined: 01/02/2008 - 11:51pm
Plus Member

How to correct the obvious differences in recording speed between the camera and Zoom I don't know, and it may not be possible. If the differential is only 1 frame per minute, in 30 minutes you'll be out of sync by a full second.

However, in post, try this: Sync the audio and video and play until you notice the beginning of sync loss. Back up a few seconds and render this portion of the material. Re-sync and repeat from this point, repeating as often as necessary. Hopefully you'll wind up with several clips, all rendered and all in sync. Combine them and you're in business.

Jack


Rick Crampton's picture
Last seen: 1 year 4 weeks ago
Joined: 08/20/2009 - 1:08pm

It's an extreme act of faith to assume that even the best of gear will hold sync for an extended period of time. I'd be surprised, given the tolerances of consumer and semi-professional gear internal crystal or PLL references, if the audio DID hold perfectsync in post. Shooting double system in the wonderful world of professional film or video demands a common sync reference and time code being recorded on the audio and video gear; and then a method to resolve the two in post.

Rick Crampton


Harlin Brookes's picture
Last seen: 11 months 1 week ago
Joined: 06/16/2009 - 6:28pm

make sure the zoom is set to 48k and not 44.1 which is the cd standard. they should hold sync both being digital.

Harry

 

 

 

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Rick Crampton's picture
Last seen: 1 year 4 weeks ago
Joined: 08/20/2009 - 1:08pm

As an experiment, earlier this year, I shot a live concert of folk-style music using my HVX-200A and a Korg MR-1000 digital audio recorder which was connected to an aux out on the PA console. In post (CS-4 )I monitored the camera audio as a reference and adjusted the external digital audio for sync. I was surprised to find that over the first hour of the show ( continuous run )the syncdrifted out a total of 3 or 4 frames, easily pulled up a frame at a time. I was prepared for a much bigger hassle but was relieved that the sync held as well as it did running wild!

Rick Crampton


filmedit22's picture
Last seen: 2 years 11 months ago
Joined: 10/14/2014 - 11:29pm

Hey guys!  I know I'm replying to an old thread here, but I was having this exact issue today and wanted to post my solution to the internet somewhere.

The iSight camera has no settings, and adjusts it's framerate by the amount of light available during the recording.  With adequate light it records at 30 fps, but will drop below that in low light.  If the frame rate is something lower than the project settings, there will be gradual audio sync loss in the project.  If you're recording a long clip in iMovie and want the audio to be in sync throughout, you need to be in bright light.  I'd suggest being near a window and using daylight.

I know this doesn't help those who have already recorded material, but this method can be used to prevent future synch issues when using import from camera with iSight in iMovie.