My Osmo action camera (Go Pro clone) started recording poorly. Black frames showing up at various parts of the video. Sound was missing. I’m hoping it is the micro SD card I was using. It was a Speed Class of 10 (min write speed 10MB/s), UHS Speed Class of 1 (again, 10MB/s write speed). I switched it out for a micro SD card rated UHS 3 (30MBs write speed).

I use iMovie and though I edit my video to try to remove the black segments, I often miss some short black segments or even a single black (bad) frame. I movie fails when I save with the message:

Share Failed
Exporting ” has failed.
Error: RequestCVPixelBufferForFrame returned 3 for absolute frame: NNNN

To locate where in the timeline the bad frame occurs I used this website to convert frame to timecode. The calculation is not difficult. You just need to know the frame rate of the video. You can check your project settings but if it does not report the FPS, just advance the video 1 frame at a time from the beginning and count how many frames until the timecode reaches 1 second. I shoot in either 30 or 60 fps.

Take the absolute frame reported in the error message and divide it by the frame rate. This is the number of seconds into the video where the problematic frame exists. Now divide the number of seconds by 60 and that is how many minutes into the video you’ll find the bad frame. Multiply the full number of minutes by 60 and subtract this from the total number of seconds to get how many seconds after the full minutes where the problem occurs. Removing the few frames around the problem will fix the issue.

Don’t know why iMovie doesn’t offer the option of removing these bad frames for you.