Zoom hn4 audio drifts out of sync with go pros

[anthonyg94617671]

So... at a previous job I worked for years with zoom recorders and never had audio sync issues; that was when syncing the audio with GH5 footage.

With a new client who uses GoPros the audio from the Zoom recorder will drift out of sync after 15 minutes or so. 

At first the client was sending me audio that was 44.1 KHZ; I explained to him that it would be 48 kHZ to matach the video and stay in sync... well guess what, I seriously think the audio stayed in sync better at 44.1 khz -- not worse than it does at 48,000.

Anyone have this problem? I want to know why and I don't want to solve the issue by having to change the speed of the audio slightly... it takes to long; I want to know why I never had this problem before now it's such a headache. 

[YANNA26705213grl5]

the 44 and 48 has to do with quality, not timing.

the codec (compression decompression) method use by camera(s) ( e.g. gh5 vs. gopro) is probably the culprit. mp4 tries to 'guess' what pixels will change in the next frame vs. what happened in the last frame(s)... and that results in slight timing alterations ( whether variable frame rate or constant frame rate ). Over time this may lead to drifting of the sync from HN4 cause the CAMERA is drifting, not the HN4.

So, check out the codec for gh5 and gopro and see if you can figure it out.

good luck

[YANNA26705213grl5]

I know it sounds crazy, but it can be nanoseconds, how long it takes for a chip to process and send to an SD card information in a particular codec, and they are all different.

[R Neil Haugen]

It is actually quite normal for non-jam-synced hardware to drift from each other over time. That is WHY jam-syncing is still a huge part of so many pro shoots.

Actually, the audio recorder is more likely to have "correct" time than that GoPro, like Yanna says. So I would match the video file to the audio for length to 'fix' that drift.

And yea, this is a very common thing to have to do. Even with good cameras.

Neil

[anthonyg94617671]

Well here's the thing... there are 3 go pros.... they roughly stay in sync with each other.

Yet, It just dawned on me why it doesn't stay in sync. 

GoPro's only record 8 minute clips or so... at the end of the clip is often a fram without audio as the clip changes. This jump forward has to be the culperate. And why 3 GoPros will stay mostly in sync, just also very.

SO, does anyone know a way to import GoPro clips as ONE file in Premiere? 

I remember with old handycam type cameras that use .mts files the "media browser" could join the clips... 

Is there a way to do something similar with Go Pro clips??

[YANNA26705213grl5]

I don't know anything about it, but years ago I took a tutorial on multicamera and basically it was source footage from various cameras with a single soundtrack...and what I did was switch from one camera to another ( depending on the action happening ) and made one video out of several cameras.

Maybe that is something  you'd be interested in exploring ?