Audio Syncing Issues with Pocket 4K

Just editing some footage (Resolve 15 Studio) from a shoot last week using my Pocket 4K and discovered a problem. Before this shoot, I had done a bunch of testing with the camera, but have discovered some sync issues that didn't appear in testing.

The shoot involved recording presenters direct to camera, with durations between 5-30mins for each take. Out of approximately 30 clips recorded two of the clips lose sync between vision and audio.

In the longer of the two, the audio drifts nine frames behind vision over 14 mins duration.

Codec = UHD ProRes 422 25fps
Recording to CFast 2.0
Off Speed = Off

Channel 1 = Sennheiser G3 Lapel into 3.5mm
Channel 2 = Rode NTG-3 into Mini XLR

BTW, with the RF receiver outputting 0dB, the audio level into the 3.5mm input is actually quite good. It is slightly noisier than the mini-XLR input, but at input level set to around 60-70% it totally usable.

Tristan, odd that most clips are fine with two having problems. Can you tell if it’s a gradual drift or at some points in the audio there are abrupt drifts?


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Tristan, odd that most clips are fine with two having problems. Can you tell if it’s a gradual drift or at some points in the audio there are abrupt drifts?


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I've just discovered two more with drift.

It's a fairly consistent, slow slipping of sync - nothing abrupt. It works about to be roughly one frame behind every two minutes.

I've sent an email off to New Magic, the tech support for Blackmagic here in Australia, about the issue.

Could it be related to something set to 24 fps and something else set to 23.976 fps?


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Could it be related to something set to 24 fps and something else set to 23.976 fps

Nope. I never use 23.976 or 24 frame rates. Always 25 fps, or off-speed 50 fps.

Camera = 25 fps.
Timeline = 25 fps.
Off Speed Record = Off.

There were no changes to the camera setting during the shoot. Camera was never cycled on/off the whole day.

Some clips in sync. Some clips out of sync. In the same timeline.

Playing the clips through Quicktime faithful reproduces what's happening in Resolve - shows some with sync drift, and some without.

Sounds like the occasional dropped frame during recording. Do you have the cam set to stop recording if it detects a dropped frame?

Sounds like the occasional dropped frame during recording. Do you have the cam set to stop recording if it detects a dropped frame?

Yes I do.

I'm having the same issue on the BMPCC 6K. any solutions out there?