Overlaid data has a long delay in video

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Jordan
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Overlaid data has a long delay in video

Post by Jordan » Sun Aug 12, 2018 10:08 pm

Hi Harry,

I've never quite gotten the data overlay and video to work quite right since I bought the app last summer- You may recall some of my posts then. Well, I went to another track event last weekend and experienced the delayed data overlay problem again. I'm not sure if the data rate is part of the problem, but the overlay is roughly 3 to 3.5 seconds behind the video when I export it. Here is a 5 lap exported video so you see what I mean:

https://drive.google.com/open?id=1ImABD ... AHd6m1R-1V

Check database says no problems discovered. In the status before I go out on track each time, it always says everything is good/ready.

When I backup the database, this info is in the email:

SOFTWARE
Product: Harry's LapTimer
Version: v21.2 Petrolhead Edition - Build: Nov 22 2017, 22:14:32
MD5: d77e56699080f015cf63985892944ab4

SYSTEM
Device: iPhone - Model: iPhone 7
OS: iOS 11.4.1 - Databases: <removed>
Available memory: 33.0 GB - GPS: Internal
UDID: <removed> (certified)
Name: Jordan's iPhone

ONLINE CLIENT
DriverID: JEA - Simplified UDID: <removed>
Server: 3 MB uploaded, 166 KB downloaded

Please let me know what other data you need to help me figure out and solve this problem. I have another track event in 3 weeks and I'd really like to have it working by then. :)

Thank you in advance.
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Harry
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Re: Overlaid data has a long delay in video

Post by Harry » Mon Aug 13, 2018 3:58 pm

No Google drive please, I do not have the bandwidth. In case you have a youtube link, I can have a look into it.

With standard settings, it is next to impossible you get a 3 seconds gap between video and data and the video being ahead of data. The other way around, this can happen if the system is overloaded and the cam requires an extremely long time to startup... Anyway, to trouble shoot, feel free to send screenshots of the Sensor Delays section in LapTimer's Expert Settings. To fix the alignment for your video, please select one of the laps from Lap List, press Edit, and select the Video / Preview row. This will bring up the Sync dialog. Move the frame marked 3 seconds back and things should be fine.

- Harry
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Jordan
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Re: Overlaid data has a long delay in video

Post by Jordan » Tue Aug 21, 2018 3:21 pm

Hi Harry,

I've uploaded it to YouTube here: https://youtu.be/pgAqd5r5DWI
Sorry it's so shaky, I'm still trying to figure out a way to improve how I'm mounting the phone so that it has less shake and vibration.

After submitting my post above, I found this post: viewtopic.php?f=8&t=4937
Which led me to this: viewtopic.php?f=39&t=4940
And I saw the part in red:
NB: in case all your videos show the same offset to lap data, the sensor / cam timing does not match LapTimer's standard settings. You need to adjust the data / video offset using the Overlay Synchronization / Video value in LapTimer's Expert Settings in this case. Do not adjust the alignment individually in this case.
I believe that is the workaround for my situation. I tried it on a clip and it worked, BUT, trying to figure out exactly how many 0.1 seconds to adjust is very hard. There's no exact spot on the track that I can clearly set a keyframe on. However, you said a 3 second delay is extremely unlikely and I would like to figure out what is causing the problem.

Here's the screen shot of my sensor delay settings: https://flic.kr/p/2aiKJvZ
Note that it currently shows 3.7 for the overlay synchronization because I've been trying to figure out the right delay. It was the default (1.0? 0.9?) when the video above (and all prior videos) were made. I have not manually changed any of the sensor delay settings.
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Re: Overlaid data has a long delay in video

Post by Harry » Wed Aug 22, 2018 2:05 pm

The way to find the precise sync is not using the video frame shown. This should be used for an initial lap end / video frame setting. Instead, use the Play function (showing the overlay in real time) and what gauges and picture. In case you are using OBD, you can use RPM displays and audio, otherwise I recommend comparing lateral acceleration gauge and cornering in the video. Once you have a guess for the sync adjustment, return to Expert Settings, update the video delay and return to Play.

- Harry
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Re: Overlaid data has a long delay in video

Post by Jordan » Thu Aug 23, 2018 2:31 am

Yes, what you described is how I got to around 3.7 seconds on the overlay delay. By looking at the throttle, g-force, and track mini map overlays.

You said previously that you don’t think it’s possible for the data and the video to be off by 3+ seconds. I would like to troubleshoot that and figure out what the problem is.

Not to confuse topics, but I read on another forum that the really bad shaking in my video is a result of the iPhone 7, and that if I buy an old 4S to use for HLT on track, it will fix the video shaking. I haven’t had time to look yet but they said there are a lot of discussions about that in the forums here.

Thank you.
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Re: Overlaid data has a long delay in video

Post by Harry » Sat Aug 25, 2018 8:01 pm

The 4S is the last iPhone without the named stabilization issues. All modern iPhones and Android phones come with one or the other stability issue.

For your offset, please first check if this is a repeating pattern or a single case. Smartphones are no real-time systems, so runtime effects can kick in at times.

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Re: Overlaid data has a long delay in video

Post by Jordan » Sat Aug 25, 2018 10:00 pm

I just ordered a 4S. Thanks.

Yes, there is a long delay between video and overlay on all my videos since I started using HlT over a year ago. I haven’t compared to see if the amount of the long delay has changed over time but it was never good.
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Re: Overlaid data has a long delay in video

Post by M3danne » Tue Sep 04, 2018 9:59 pm

Hi.
I have about 30 sek delay ... data is correct but the vid starts wayyy to late but finishes on time so I don’t get the last data of the lap and I don’t get the beginning of the vid. It has been like this all summer but not on the first 3 years of using it. I have deleted the app 3 times and downloaded it again without improvement.
It’s btg by harry.
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Re: Overlaid data has a long delay in video

Post by Harry » Thu Sep 06, 2018 9:15 am

Video recording always starts late: LapTimer detects passing the starting line behind the line and the cam requires an additional startup time. This sums up to 1 or 2 seconds usually. In case you want video from the beginning, start recording manually before leaving the pits. In case you face a 30 second gap (or anything beyond 2 seconds), your device is probably overloaded. This is nothing LapTimer can fix. Please report which device / OS you are using. Kill all apps running in background, free up memory, restart the phone, reduce the amour of videos in your media library etc.

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Delay in video

Post by M3danne » Tue Sep 25, 2018 9:38 am

I know they have a delay, but not always and not 15-60 sek delay. The lasts 3-4 month (about 100+ laps at the ring) the laptimer has started earliest at T13!! I even bought a new Iphone 8 because you imlied that my phone could be the problem. I have bought and downloaded all your different apps. I have delited them completly and downloaded them again.
So, please help me sort my problem out.
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