GPS Overlay Defect. (Virb edit 2.9.1, Firmware 3.90)

Former Member over 10 years ago

First up, its great to see a properly open forum with conversation's including the developers. I'm encoraged to see that a lot of work is going into the Virb Edit software and the improvements are noticable. However, there is DEFINATELY a problem with overlap miss-match and after quite a lot of time investigating the causes I believe I have figured it out.

Below I believe I have found both a Firmware and Virb Edit defect which contribute to the problem under two different conditions. I have made this determination after a week of using my Garmin Virb on a skiing holiday each day. As a result of these defects the overlays are off almost all of the time, unless corrected, but I now have the formula to correct them. The following has worked 100% of the time accross 50 odd videos taken over the week.

There are two different Senarios:

1. Camera is on and has GPS fix at start of recording - Set to record GPS only when recording video.

The Camera records a variable in the GPX file called gpxtrkoffx:StartOffsetSecs. If the Camera is on and with a GPS signal at the start of the recording this value is typically between 0 & 4 seconds, most commonly 4, and the GPS file is shorter than the video by the same amount. The issue (as far as I can see) is that Virb edit applies this offset the wrong way around. If this value is 4, with video at 4 seconds in (0:04) the GPS should be at 0:00 (i.e behind the video). However, if you view the GPS sync in Virb Edit the Video is at 0:00 with the GPS set to 0:04 (i.e ahead of the video). This means that the overlays will run 8 seconds ahead.

To correct this, move the video to 0:04 and (with the GPS now saying 0:08) move the bar to 0:00. In my case the overlays now line up.

2. Camera is off and the record switch is used to start recording - Set to record GPS only when recording video.

(I'm let certain of my diagnosis here, but this is what appears to be going on).

In this case the camera has to get a GPS fix before it can start to log in the GPX file. This can take some time, in the attached GPX it seems that was 1 minute 20 seconds. My video file is 20:51 and Virb Edit tells me the corresponding GPX file is is 19:31 (01:20 shorter). If I look in the GPX file the gpxtrkoffx:StartOffsetSecs is 4.090. This is odd, I'd expect it to say 80. I thought for some time that this would mean that the total offset of the GPX file to the video would be 1:24 meaning the behaviour was conistent with Scenario 1, but it's not, the offset is 1:20. This may mean that there is a firmware defect in that the gpxtrkoffx:StartOffsetSecs value is set incorrectly when the camera does not have a GPS fix at the start of recording.

Regardless of this potential firmware defect Virb Edit makes a right mess of lining this up. If I go to GPS Sync in Virb Edit I can clearly see the GPX file is only 19:31, yet Virb Edit once again sets the GPS data to start ahead of the video by 4 seconds (with video at 0:00 GPS is at 0:04). It's applying the (incorrect) offset incorrectly again. It completely ignores that the GPX file is shorter in duration than the video. If I allow Virb Edit to play this as is, it will play the GPS data 1 minute 24 seconds ahead.

If I move the video to 1:20 and then set the GPS data to 0:00, I of course have no GPS data for the first 1:20 of the video (which is correct the Camera wasn't recording it) and then a correctly aligned overly for the remaining video. Both files will correctly end at the same time.

In summary then I believe there are potentially 2 defects here:

1. The gpxtrkoffx:StartOffsetSecs is applied by Virb Edit the wrong way around. If gpxtrkoffx:StartOffsetSecs is positive Virb Edit should use this to put the GPS data BEHIND the video not ahead as is currently the case.

2. If the camera does not have a GPS fix when recording starts the gpxtrkoffx:StartOffsetSecs value is incorrect. In my case the GPX file was 1:20 shorter than the video and lines up perfectly if played as such. gpxtrkoffx:StartOffsetSecs should have been 80.

Until a fix is produced these defects are easily worked around. Simply calculate the time difference between the two files and then set the Video ahead by the corresponding amount. Works every time!

Now that I've figured this out I'm able to happily use my Garmin Virb for the first time. I plead with the developers to take a look and fix this problem, it's really quite straight forward and I can see from the forums it's causing people a lot of frustration with what is otherwise a great camera and pretty good editing software.

I've attached some annotated screen shots of the issue for scenario 2.

The original GPX file is here: https://www.dropbox.com/sh/85n0bcjqp9ujuox/AABmN0PfsyCYzYIdZ8xll8PSa?dl=0

Regards,
Paul.

0 Former Member over 10 years ago

Paul,

thank you so much for your thorough investigation. I asked our Software Quality team to try to reproduce this. If what you found is true, we should be able to get #1 fixed on the VIRB Edit side fairly easily. If there is a firmware issue about #2, we'll try to fix that as well, but it might not be quite as swift.

We very much appreciate your help.

0 Tim_B_ over 10 years ago

Sounds like he might be on to something, invariably my overlays seem to be out by around 5 seconds even though Virb Edit tells me that they are synced. They are ok once adjusted.

0 SVXVoRTeX over 10 years ago

I too would like to chime into this. Took my first ride of the season and the GPS overlay is off by 5-10 sec. Absolutely useless. I used two GPS devices (Fenix 2 and Virb Elite) to validate and the Virb is just, wow... Is there a way to fix this offset? I really needed this video today for training purposes. ANT+ HRM was accurate.

Second issue, half way through my ride, the camera STOPPED recording and restarted recording. Amazingly, the second video was in sync! Validated via Fenix AND a town speed radar which was recorded! Why did it stop in the first darn place?

Third, Fenix 2 remote works maybe 1/4 of the time? It simply cannot find the camera! Last week in Vail the Fenix 2 would just keep searching, eventually connecting. Today, I was trying to control the cam (helmet mount) from my cycling bar with the Fenix and it just did not connect. To that, I was using the Fenix with my HRM & Spd/Cad on my ride. Perhaps it cannot control while the Fenix is in an activity as well.

This stinks to high hell. I bought Garmin for the name, "quality", and features such as GPS, WiFi, and ANT+; but, am finding that the Virb is not living up to those standards. Last week I could not even upload my slope results or see them on Garmin Connect. This week, I try to ride and this? We are talking a total of perhaps 4 days use (bought Feb 17th) and problems out of 3?

After all of this nonsense, I will be buying a Sony cam (AS100V or AZ1) this weekend to test their GPS capabilities. I hope Garmin can get these issues resolved, otherwise I will be moving down another path.

AND BTW, COULD SOMEONE AT GARMIN PLEASE EXPLAIN TO ME WHY MY EMAIL IS MY USER NAME?? I CREATED A SEPARATE USERNAME!

0 Former Member over 10 years ago

Paul,

thank you so much for your thorough investigation. I asked our Software Quality team to try to reproduce this. If what you found is true, we should be able to get #1 fixed on the VIRB Edit side fairly easily. If there is a firmware issue about #2, we'll try to fix that as well, but it might not be quite as swift.

We very much appreciate your help.

Hello Falagar,

Would you have an update on the issue? I have been struggling with the cold start sync since Dec 2013 and it would be really awesome to hear we might have a solution soon. Btw, can't Virb Elite just start recording gpx files (or what kind of files it records the input from sensors) always at the same time as it starts recording the vid and just record all values as a zero until its gets a gps fix? That way both files are always in equal length and you will have no issue with aligning them at all.

Thx for info (I tried to start a new thread, but before I got any answers I found this one)

0 Former Member over 10 years ago

p.s. Even when correct track alignment is achieved, I can't get speed and G's readings to align. Seems there are more than just one file this sort of data is recorded in and Virb Edit only allows to change the alignment of track, not the other values?

0 schinder over 10 years ago

I too would like to chime into this. Took my first ride of the season and the GPS overlay is off by 5-10 sec. Absolutely useless. I used two GPS devices (Fenix 2 and Virb Elite) to validate and the Virb is just, wow... Is there a way to fix this offset? I really needed this video today for training purposes. ANT+ HRM was accurate.

Yes, it's simple to realign. In the OS X version, it's scissors -> GPS Sync... (I assume that's the same in Windows, although maybe they use a different icon for the trim functions). Up pops a slider and you can make adjustments. I generally expand the map and align on intersections, although I have used altitude in the overlay sometimes when I'm climbing and I know the altitude of some landmark (and I trust the altitude in the track, which is almost never for a VIRB track).

Second issue, half way through my ride, the camera STOPPED recording and restarted recording. Amazingly, the second video was in sync! Validated via Fenix AND a town speed radar which was recorded! Why did it stop in the first darn place?

I'm going to assume you mean it kept recording and started another clip. That's a function of the old filesystem they use on the microSD card in the VIRB, FAT. It has a file size limit of around 4 Gb, so when one clip comes close to that limit, they start another. At 1080p@30fps, that's about 23 minutes of recording. Nothing's wrong, that's the way it works.

Third, Fenix 2 remote works maybe 1/4 of the time? It simply cannot find the camera! Last week in Vail the Fenix 2 would just keep searching, eventually connecting. Today, I was trying to control the cam (helmet mount) from my cycling bar with the Fenix and it just did not connect. To that, I was using the Fenix with my HRM & Spd/Cad on my ride. Perhaps it cannot control while the Fenix is in an activity as well.

This stinks to high hell. I bought Garmin for the name, "quality", and features such as GPS, WiFi, and ANT+; but, am finding that the Virb is not living up to those standards. Last week I could not even upload my slope results or see them on Garmin Connect. This week, I try to ride and this? We are talking a total of perhaps 4 days use (bought Feb 17th) and problems out of 3?

After all of this nonsense, I will be buying a Sony cam (AS100V or AZ1) this weekend to test their GPS capabilities. I hope Garmin can get these issues resolved, otherwise I will be moving down another path.

AND BTW, COULD SOMEONE AT GARMIN PLEASE EXPLAIN TO ME WHY MY EMAIL IS MY USER NAME?? I CREATED A SEPARATE USERNAME!

Yep, the remote on devices (I have a Fenix and an Edge 800) have never worked reliably. Doesn't bother me, but my VIRB Elite is always within arms reach. If you need the remote, you can't really rely upon it.

0 Former Member over 10 years ago

I have the Virb Remote and even that can be hit and miss (but better than using my 810 as a remote).