LapTimer fails on a Nexus 5

Help on issues you run into with LapTimer; in case you have a question on how to use LapTimer, use the forum "Using LapTimer" instead
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Harry
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Re: LapTimer fails on a Nexus 5

Post by Harry » Wed Apr 23, 2014 9:06 am

Yes, too big to process currently. Either convert the video to use a lower resolution or higher compression. Please make sure it is in .mp4 format, otherwise Android will not be able to display thumbnails. Furthermore, don't use spaces and accent characters in the video's file name.

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Re: LapTimer fails on a Nexus 5

Post by DjaCLF111R » Sun Apr 27, 2014 9:32 am

Hello Harry thanks for the tip and of course it works - thank for that and the HLT app wich is great, efficient and easy to use
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Re: LapTimer fails on a Nexus 5

Post by GarryR » Tue Apr 29, 2014 1:36 am

Harry -- Petrolhead Android seems to be coming along and I'm looking forward to getting great use from it, but this weekend I had some problems.

On a new Nexus 5 with 32gb:

1) On an overlaid MP4, telemetry (OBD and GPS) froze in a "stuck" position after about 5 laps and never came back (even though video was still OK).
2) On the above video, accelerometer never seemed to work, although it did work on some of my other test overlaid videos.
3) Displayed speed didn't seem accurate in several cases. At one point my actual on-track speed was 122MPH, while HLT was showing 105MPH. In another case speed went from ~50MPH to ~80MPH in ~1 second, which my car cannot do (unfortunately :cry: . Are these artifacts of internal Nexus 5 GPS @ 1 Hz?

Other things came up which were (I think) part of my own learning curve on HLT. Thanks for your great work!
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Re: LapTimer fails on a Nexus 5

Post by Harry » Tue Apr 29, 2014 8:46 am

On 1) did you discover this driving a west coast track in the late afternoon / evening? despite that, this typically means you had no GPS reception starting at a a certain point in time - which can have several reasons.
On 2) take care you go through the calibration design process: mount your device into a stable mount first; start LapTimer and take care the acceleration shown is zero (you may need to wait a few seconds); in case it isn't, reset calibration by either touching the acceleration circle in the bottom left of the video view, or be pressing any of the Max G gadgets (GPS View, Timer View...). Please never move / rotate the device while already driving, this may keep LapTimer from calibrating correctly or disturb an existing calibration.
On 3) bad GPS reception. LapTimer does not calculate speed itself but simply stores what it gets from the sensor. GPS speed is notorious late and sometimes too low for peak speeds achieved for a short time only. In case you reflect on speed development in the video overlay - that is interpolated speed. You always need to check the raw data in LapTimer Data Recordings area to understand the root cause for strange speed displays in videos.

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Re: LapTimer fails on a Nexus 5

Post by Kojiro » Wed May 07, 2014 4:39 am

Hooray for search! I was able to find this solution to "invalid master video" on my Android. I have 20+ minute videos because I guess I did not setup the timer correctly, my whole 20 minute track session is one lap. And it wouldn't overlay due to the file size being over 2 GB. Thank you for this solution. I would only suggest a better error message, like "master video file size is too large; please re-encode and try again" or something similar!
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Re: LapTimer fails on a Nexus 5

Post by Harry » Wed May 07, 2014 7:02 am

Kojiro wrote:Hooray for search! I was able to find this solution to "invalid master video" on my Android. I have 20+ minute videos because I guess I did not setup the timer correctly, my whole 20 minute track session is one lap. And it wouldn't overlay due to the file size being over 2 GB. Thank you for this solution. I would only suggest a better error message, like "master video file size is too large; please re-encode and try again" or something similar!
Yes, I will either add this message or fix it :-)

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Re: LapTimer fails on a Nexus 5

Post by GarryR » Wed May 07, 2014 11:56 pm

Harry wrote:On 1) did you discover this driving a west coast track in the late afternoon / evening? despite that, this typically means you had no GPS reception starting at a a certain point in time - which can have several reasons.{/quote}
Nexus 5 is mounted under the windscreen with no interference, unless it's transient interference from the rear view mirror? That seems unlikely, aren't there multiple GPS satellite fixes?
Harry wrote:On 2) take care you go through the calibration design process:
Thanks, I'll be more attentive to this.
Harry wrote:On 3) bad GPS reception. LapTimer does not calculate speed itself but simply stores what it gets from the sensor. GPS speed is notorious late and sometimes too low for peak speeds achieved for a short time only. - Harry
OK, and presumably this is why you recommend external GPS, which I'm considering.
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Re: LapTimer fails on a Nexus 5

Post by bigmillertime » Wed May 21, 2014 5:55 am

Thanks for all the updates Harry!

Question, how do I limit the video file to stay under 2gb?
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Re: LapTimer fails on a Nexus 5

Post by bigmillertime » Fri May 30, 2014 6:48 am

Anyone?
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Re: LapTimer fails on a Nexus 5

Post by Harry » Fri May 30, 2014 6:57 am

Still working on this... For a HD video, 2 GB are roughly 25 minutes and for FullHD it is 10 minutes.

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