Very Confused

[peloton]

I've been using HLT for a few years. I consider myself an "intermediate" user, not advanced or expert, not a novice. I'm seeing some odd behavior despite having used the app successfully just last month and other times in the past.

Background:
- HLT on an iPhone 11 Pro Max
- External GPS (XGPS160)
- One of the recommended OBD transmitters
- GoPro 4 Silver
- Brainerd International Raceway, 2 days
- 4 sessions day 1, managed to forget to connect the phone to the GoPro for session 1
- Remembered for remainder of weekend
- 3 remaining day 1 sessions had video captures that spanned 2 .MP4 files
- Copied .MP4 files from SD card to laptop
- Merged session video files with Windows Video Editor
- Copied merged video files to HLT via iTunes
- Ran HLT, went to first lap of sessions, linked correct (to the best of my knowledge) videos to sessions

Problem:
- When I go through the laps and look at each lap's video in session 2, some are correct and some jump to the last video of the session.
- This behavior is NOT deterministic. When I first came back to debug the issue, laps 1-5 had the correct videos, laps 6-9 used the SAME wrong video (last lap), laps 10-11 again had the correct videos. Lap 11 having the last lap video that 6-9 ALSO used.
- However, I came back to it an hour later, killed the HLT app, went back in and ALL the laps were correct! Excellent!
- However, I then went to session 3 and saw similar behavior (last lap getting used by the wrong, and more than one, earlier laps).
- I put it away, came back the next morning and discovered that session 2 had reverted to this odd behavior!
- Today, a couple days later, I'm seeing similar behavior, except this time LAP1 has the last lap data.
- What the heck is going on?

I looked at the session 1 video end times versus the non-linked raw video on the PC (eyeballing the finish line). It looks like the app is 1-3 seconds off the lap end times that I believe I'm seeing in the video.

I have not exported any of the videos to see if it magically chooses the right one even though it's chosen incorrectly in the app. I also haven't bothered to process day 2. I want to resolve this first. I also want to resolve this before I run at Road America for the first time in 4 days.

Appreciate any help you can provide, Harry. I love your work. I'm hoping I'm doing something wrong on my end that's easily fixed.

Thanks!
peloton

[Harry]

To start with, every lap can be linked to a raw video including the time offset of the lap's end relative to the video's start. The relation is documented in Video Documentation (see http://www.gps-laptimer.de/documentation). Like all lap data, this link is stored in LapTimer's database. The database (and changes applied) is stored when sending LapTimer to background. This means there is a chance changes are reverted when killing the app without inactivating it first. There are always many options to handle apps, you may want to check if the way you handle it conflicts with this approach.

When joining session videos, the relation between laps and video need to be re-established. This can be quite complicated: LapTimer decides on lap-groups = session by comparing a lap's end with the next lap's start. In case they are the same, the two laps are considered part of the same session. Whether the video spans across both or not does not influence lap grouping to sessions.

When re-syncing a lap to a video (e.g. the first lap of a session), you will get prompted whether LapTimer should apply this to the complete session. You should select this option almost always. But: this extension of syncing applies to what LapTimer considers a session. And this is *not* influenced by the extend of the video but by the lap end/start comparison described above only. So when syncing a long video to the first lap of the first session, the sync will not be applied to the second session! In case you want that, sync the first lap of the second session too.

To sum up: keep LapTimer's session grouping in mind. It cannot be influenced. From my PoV, there is only one situation videos should be joined. This is the situation you record with an action cam creating video chunks - like GoPros with their 4GB chunking. Joining videos covering more than one session will make things complicated and will not add a benefit. You will not be able to create multi-session overlays anyway. Again, this is limited by LapTimer's session grouping.

I hope this clarifies the app's behavior.

- Harry