Video/Audio sync issue - sampling rates?

[EliasMooseblaster]

I've noticed, when I try to film and record separately, I end up with a weird syncing issue: I can get the video to sync with the start of the audio track, but they seem to get more out-of-sync as the video goes on.

 

Am I just two or three frames out when I line them up, and that lag snowballs through the video? Or could it be something to do with sampling rates (my phone camera typically does 25fps; DAW is recording at 44.1 or 48 kHz)?

 

Anyone else found this problem?

 

(If it helps diagnose: I record in Ardour or Audacity; audio and video are edited together in KdenLive.)

[BigRedX]

If the audio and video slip more out of sync the longer the video runs, then it will probably be a combination of both frame rate and sampling frequency, as they are completely separate attributes and not dependant on each other.

 

File Info/Properties should show you the frame rate and audio sampling frequency for your video and audio. What platform are you on? Windows? Mac OS? Linux?

 

What are you using to record the video and audio? How are you getting the initial sync point? There's a reason why film makes use a clapper board at the start of each take.

 

IME video tends to default to 48kHz sampling frequency whilst many audio applications use 44.1kHz. So start off by making sure any new recordings are done with everything running at the same sampling and frame rate. For existing recordings you may have to use a conversion tool to get them the same, as many video and audio editors will set the project to the attributes of the first Imported file and then impose those attributes on anything imported subsequently.