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GoPro video faster than session data

I just tried out RaceChrono a couple of weeks ago and also recorded some video on my Hero 6 Black. I signed up for the Pro trial and tried to import the video from the GoPro. I can get it synced up to the start/finish line, and fine tune it with the +/- 50ms buttons in the first couple of corners so that it matches the accel/decel curve, but by the time it gets to the end of the lap, the video is always a couple of seconds ahead of the session data recorded by RaceChrono.

I've tried both the original GoPro MP4 files and my post-processed combined video file with the same results either way. Am I doing something wrong here? The video is 1080p60 and my phone is a Pixel 1. This doesn't seem like a slow video playback issue, since the video is faster than the session data.


  • Hard to say what's wrong without seeing the raw video and the session, but I haven't seen such issue when using raw video from GoPro. You should always use the raw video, as post processing on PC/Mac might change codecs to incompatible ones.

    Easiest way is to sync according the finish line if it's visible in the map. Or maybe some other landmark visible both in the video and the map. Take a look if the video sync stays same lap-to-lap. GPS data quality might affect too, so if your data is not very good, then it will make the sync harder, and the lap timer accuracy will suffer.

    If you want me to take a look, then please share DropBox/Google Drive links to the session (.rcz share) and the raw GoPro videos linked to your session.
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