Audio recorded at wrong sample rate

Report · Jul 25, 2019

Our sound person recorded at a different audio sample rate for the length of a 45 minute live set...
It's quite out of sync by the end on all cameras. All sorts of headaches.

Sound was recorded at 44.1, all our cameras were 48k.

I've been going in circles for hours trying to find a way to resolve the audio drift. Ideally I'd like to "stretch" the 44.1 track to the correct length, because we have cameras which have dozens of different clips. Some cameras are a single clip, some are up to 16 clips.

I've tried using the Automatic Speech Alignment tool in audition, but doesn't seem to help. I've tried interpreting it at 48k in audition (shortening the clip) and exporting it as such - even more out of sync.

Any other suggestions?

Report · Jul 25, 2019

Audio drift is almost always impossible to avoid on long recordings since the internal clocks in each recording unit will have a small mismatch. Even if the recording was recorded at 48 kHz you would still have had some drifting of the audio.

When i cut music concerts i always cut with the audio from the camera/cameras and then sync the external audio to the first song and cut the audio then re-sync for each new song to get away from the drifting. It´s easy to mask those cuts with short audio transitions.

Report · Jul 25, 2019

That seems sensible. It's still annoying that it was exacerbated by audio person using the wrong sample rate. I'd like to get it closer.

Report · Jul 25, 2019

In my experience, sampling rate won't affect sync. One second is one second. No matter how many samples are in that second, PP will take one second to play it back. Sampling rate only determines the upper frequencies of the recording. (Half the sampling rate is the highest frequency you can capture.)

I've never had a problem mixing 48, 44.1 and even 32 sampling rates in the same sequence.

It's also my experience that poorly made audio recorders will drift even when the sampling rate matches, whereas a well made recorder won't drift. I found the Zoom H4n well made, and am currently using the Zoom F4 without any sync issues even over 2 hour recordings.

Having said that, and having used some poorly made audio recorders that required attention, my habit was to line things up at the start of the clips, then adjust the speed of the audio until they also lined up at the end.

Report · Jul 25, 2019

Agreeing with others, sample rate has nothing to do with the drift, just the nature of audio recorders. Put a razor cut every so often and re-adjust audio clip with a nudge. Did you know you can change the timeline markers from frames to audio samples? That will allow you to make finer adjustments to the audio position, when moving one frame is not precise enough.Click the wrench at lower right of PROG monitor and enable Show Audio Time Units. Then zoom in as needs to match up waveform to other audio, typically the audio attached to video which does have the correct timing.

Thanks

Jeff

Report · Jul 11, 2021

I had a similar problem I believe with a significantly smaller audio file size, but this is what I did.

I used an application called Handbrake which is a file conversion application to convert the originally sampled audio into a sample rate that I wanted to use and then used the original video file so there isn't any lag.