RaceChrono problem merging two consecutive Gopro video files

I've had this problem lately. On longer sessions Gopro splits the video to multiple files and Racechrono syncs these back together again. So if I make sure the first video file is synced correctly (using GPS data) the following "link after..." video files should be synced too? But they are not. There's a glitch and the sync goes off a second or so.

Here's a short video showing at about ten seconds in what it looks like going from the first to the second video file.

Can this problem be dependent on if I set the Gopro (Hero 7 Black) to HEVC or not?


  • edited May 2020
    Which phone is it, and please share me the files (rcz and the video files) on my email?
  • Huawei P30 Pro. Mail coming! Thanks!!
  • edited May 2020
    @MagnusThome Got it, thank you.

    I will probably test this over the weekend, but my guess is that this is somehow related to the firmware of the phone, not a general problem on Android, or a problem with the video files generated by your GoPro. I say this because this has been tested a lot in the past and never any problems with it. Also this part of the code hasn't change in maybe 3 years... But this is just a guess, need to do the real world tests.

    That said, also new GoPros have a very high bitrate h.265 files, and I cannot say these would have been tested that much...

    1) Which Android OS version does your Huawei phone have? Or maybe the Huawei firmware version? I have a few Huawei phones, possibly the P20 with 9.1.xxxx firmware is the closest to yours.

    2) Does this happen in analysis too? I wonder if the OS (or the video metadata) is just reporting the video duration wrong?
  • EMUI v10.0.0 // Version // Kernel 4.14.116

    Yes, running video playback in analysis behaves 100% the same.

    I managed to sync the two files correctly instead of just "link after..". I think I GPS-synced the second video and then somehow managed to sync the the first manually. Then the data graph showed the two "video markers" overlapped and only one of them would be visible in the video window. The other one was just black
  • The second video of the two doesn't sync correctly using the GPS data it seems. So my description above is probably the wrong way around, I synced video2 manually first. I'm fiddling with the two now. BRB
  • edited May 2020
    @MagnusThome Exactly like you say; a workaround is to manually sync the second file. Just look at the graph's video markers where the first video file ends. Then place the second file's start a second before that.

    As the analysis screen behaves the same, the problem is not a video encoding glitch, but a glitch with detecting the video duration. For some reason the video length is detected to be one second longer than reality, causing a blank one second on the exported video (and analysis), the second video going out-of-sync. I will try your videos and see if I can re-produce the problem. If I can, I will probably try a different method of resolving the video duration. Provided that this is a problem with the operating system (or phone firmware), and not the GoPro videos themselves!
  • edited June 2020
    @MagnusThome the problem is reproducible and I will be able to offer a fix for this. It seems to be an Android problem, but I can fetch the duration with a different method. The iOS app is not affected by this problem.
  • That is super-news! Thanks!!!
  • edited June 2020
    It's funny that fetching the duration from MP4 is super easy, but still Android fails to do it for this particular file... It's almost a full second off. The other file you sent is fine. And I've never seen this before, so must happen on certain files only...
  • HEVC files?
  • edited June 2020
    I've been using HEVC for couple years now for my own videos, and first time I see this... Also the problem is on the first file only.
  • Did a recording on the road today, just to check that it wasn't an odd fluke getting this a few times. But the problem is there consistently. Do you want two new files to check against?
  • No need, I'm about create a beta version that you can test.
  • edited June 2020
    should be fixed in v6.4.1
  • Worked perfectly now with 4.6.1 !

    Huge thank you!

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