iOs and GoPro video sync and exporting laps

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gremlin
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iOs and GoPro video sync and exporting laps

Postby gremlin » Tue Apr 24, 2018 4:07 pm

I've re-read the video documentation for the 5th or 6th time, and picked up a few more nuggets, but I've got a couple of issues I really would love some help on, let me run through what I've done first

config: iPhone 6, Bad Elf Lightning GPS, Kiwi ODB II Adapater, Go Pro Hero+ Camera on WiFi, connected to a 981 Cayman S

    Set the software up for my track
    Set video mode for external camera only and ensure it's linked
    See laptimer is all set to go on status at the top.
    Ran my laps, validated I have data, and videos are recorded
    Put the Micro SD from GoPro into an SD Adapter then when the pop-up occured transferred all videos to the iPhone
    (This is where issue #1 occured, the videos came in with the time shifted (As if the GoPro is in a different time-zone, although the clock on the GoPro is correct, and there's no timezone setting I can find)
    Back to lap timer, looked at my sessions (I'd really like this to be a view I could make default) and picked the session I wanted to associate
    Tapped on the empty video square
    This is where I get confused the documentation says to click re-link, but there's no re-link button in this dialog, at the bottom of the screen is a Blue camera with a dark grey camera sort of shadowed behind it, clicking this brings up the video-list, and tapping on a video here will bring up a dialog that has a "Re-link" button on it, so I'm thinking I got this right
    Now I've got an overlay but there's a problem with it
      The video lags behind the data, by the end of the lap it's significant, you can watch the g-bubble and the steering wheel, or the track map and it's clear that these are not correct

I've found the "Overlay Synchronization" setting under the expert settings dialog (it's currently set to 1 second). I've tried messing with this a bit then going back to the videos and nothing seems to change, do I need to re-link a video after I change this? In which direction should I move it, the description in the documentation is unclear. If the data is ahead of the video (shows I'm turning a corner before the video get's there) do I want to increase or decrease the value here?

The next thing I did was try to export some video even though it was off, as I figured if I could view it on a larger screen I might be able to see the laptimer on my dash (it's in shot) and see how far off it is to help me figure out the correction. When I do this however it asks me which lap numbers to export in the first dialog, however those lap numbers aren't displayed on my laps when I'm picking them to view to begin with. In addition it doesn't seem to allow me to scroll left or right when I touch the arrows to pick more laps. I have more laps in the session then are shown there but I can't export the entire session.

Any help anyone can give me here would be greatly appreciated. These are the last issues I'm having now that I've gotten the GoPro more stable, and just working better.

thank you


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Harry
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Re: iOs and GoPro video sync and exporting laps

Postby Harry » Wed Apr 25, 2018 8:40 am

Hi,

GoPro's do not have a timezone setting. This means the timestamp stored cannot be mapped reliably to LapTimer's timestamps. However, it has no influence on overlaying etc, it just would be a candidate to replace re-linking with an automatic operation.

The Re-Link button is the one with two cams, a blue one and a half transparent blue one.

Overlay Synchronization is applied when overlays are added in real time (Play button in Lap Details) and when running a video export (Export button in Lap Details / Video section). It is available to compensate individual real time timing behavior of specific devices and something you adjust once. When changing the sync setting, it will take effect for any further real time overlay, but certainly not for videos created including an overlay (Export).

In case the sync differs for the beginning and the end of a video, there is an issue with the video's timestamps that needs to be adjusted using some external tool. I have seen this for some Android video recordings in the past, but not for HEROs.

There are two lap indexes used throughout LapTimer: alls laps have a technical index (position in database). It is the number you see in Lap Details dialog title bar, export scope, or lap sync listing in Video Details dialog. The other index is track or session-relative. These indexes are used when showing the export range in Overlay Configuration. To map both: look up the first technical index in session grouping in Lap List, it corresponds to Lap #1 in Overlay Configuration.

- Harry


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Re: iOs and GoPro video sync and exporting laps

Postby gremlin » Wed Apr 25, 2018 5:24 pm

Thank you!

I got this working, and figured out a 0.8 value seems to make this better, it's within .1 of the timer I can see on my dash. Picking the first lap and then the first video seems to get it to pickup the video for all laps even though it's split, that's amazingly cool! Thank you.

How do I get it to export more laps, for instance if I wanted to export the be the entire session? Clicking the arrows doesn't seem to actually scroll the values.


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Re: iOs and GoPro video sync and exporting laps

Postby gremlin » Wed Apr 25, 2018 5:36 pm

Oh and what I figured out on the overlay synchronisation was if the data is ahead of the video reduce this number, if it's behind increase it. I ended up using MPC-HC (Media Player Classic) on windows which would let me step through the video frame by frame. I then watched the timer on the dashboard and tried to sync the change of the overlaid clock with when that changed (it only shows seconds so it takes a bit). I tried 4 different values before coming up with the one which worked for my setup. Then I checked that the G meter seemed to line up with the steering motion in the car, and the map position seemed accurate as well.


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Re: iOs and GoPro video sync and exporting laps

Postby Harry » Wed Apr 25, 2018 8:11 pm

Depending on the OS and OS version, not every frame is shown in the sync dialog. For me, the best approach to sync data and video properly is as follows: I sync data/video to the end of lap roughly. Next, I watch the overlay using the Play button. Sync is best spotted by watching the line driven against lateral acceleration. In case you have OBD, RPM vs sound is a good measure too. In case I feel data and video are off, I return to the sync dialog and use the buttons to increment / decrement the sync by 0.1s. I ignore the frame shown during this step. Repeat until it is fine.

Harry


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Re: iOs and GoPro video sync and exporting laps

Postby gremlin » Wed Apr 25, 2018 9:25 pm

Thank you.

Any idea why in the export dialog I can't get more laps than what is shown in the boxes. In the screen marked "Overlay Configuration" it shows only about 5 laps to select from but there are arrows eihter side which makes me feel like I should be able to scroll and select more laps. Again I'd really like to export the entire session and can't seem to do that.


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Re: iOs and GoPro video sync and exporting laps

Postby Harry » Fri Apr 27, 2018 10:09 am

LapTimer detects session boundaries by watching time gaps between end and beginning of laps. If e.g. one records 10 laps and deletes lap #5, he/she will get two session made up from #1 to #4 and #6 to #10. There are other reasons gaps can occur. For video overlays, video coverage is taken into account too. If e.g. the video covers lap #1 to #7 only, you will get 7 and not 10 laps for overlay.

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Re: iOs and GoPro video sync and exporting laps

Postby gremlin » Fri Apr 27, 2018 10:55 pm

In this case I have video footage for the entire session (split into 3 files by the go pro). All videos are present. I have associated the video with the session and with every lap I can view a video with an overlay. I just can't export a video for the entire session and I can't understand why. It's almost like the UX is there but doesn't actually respond to my touching it.


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Re: iOs and GoPro video sync and exporting laps

Postby Harry » Sun Apr 29, 2018 10:20 pm

You need to join the fragments in case you want to export the full session. Use ffmpeg or Handbrake on your PC.

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Re: iOs and GoPro video sync and exporting laps

Postby gremlin » Mon Apr 30, 2018 8:40 pm

Gotcha, but if I do this, it's going to require I manually sync the video correct? I wish there was a way to let it know that this was the video and not have to do that, I find it super difficult to sync the video manually, partly because the location for the start finish of my tracks is in the middle of the straight somewhere with no visible landmark to the car, so it's quite onerous and involves making sure the timer is actually in the shot to manually adjust, and partly because of the bug which causes the dialog to become unresponsive and you have to start again after an adjustment or two.



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