Problems with video overlays

[Harry]

Hi,

Can you please check if the acceleration and GPS information is in sync? Synchronization is a difficult topic as even small discrepancies are recognized by us humans.

- Harry

[olwe]

Thank you for the fast reply.

1. In one video accelleration is right on; in another one it is slightly off.
2. Neither is timed with the movement on the map.
3. The lap timer is mostly ok.
4. GPS movements seem to come in big steps. Maybe my sampling rate is too low. What sampling rate do you recommend, and how do I set it?

Any other recommendations?

Ola

[Harry]

Hi,

Sampling rate is 1Hz, no way to change this with the internal sensor. Version 13.4 smoothes the overlay to every frame, so you should not see any 'steps'. Which version do you use? In case GPS rate is worse, you have bad reception and need to change the iPhone positioning - or go with one of the external sensors compatible. Acceleration is aligned to GPS during recording, so you cannot change it 'after the fact'. You can change the sensor synchronization in Settings -> Expert Settings.

Finally, in case your video is not in sync with the GPS / acceleration recording, you need to lengthen or shorten the end of the video. LapTimer always aligns recordings and video by the end of track. LapTimer v14 will have an Expert Setting for this, maybe it makes sense to wait some more days / weeks.

- Harry

[olwe]

Harry,

I think you are putting your finger on the problem being with the GPS reception. Do you have a recommendation for an external sensor? Also, how do you charge the iPhone when hooked up to an external sensor?

I look forward to version 14.

Ola

[Harry]

Check this links please: viewtopic.php?f=6&t=215 and LapTimer Compatibility

[stltri]

Hi Harry,

Tested the laptimer this weekend. Got good videos but when I tried to overlay data, it wasnt imbedded in the video after processing. I uploaded video (after overlay) to macbook thinking the iphone 4 could not display video, but the video still did not have overlay on the macbook. Thoughts?

[Harry]

Hi,

Three questions / were does the process stop?

You pressed the 'Overlay' button and LapTimer started to show the number of frames processed?
It showed a message that the video is sent to the Photo app?
Finally you were back in Lap Details showing a thumbnail of the overlayed video.

- Harry

[stltri]

Over 6400 frames.
Video was sent to Photo app.
Back in Lap Details, but thumbnail shows same video (without the overlay).
Process never stopped. Looked like it completed normally.

[Harry]

What does 'Process never stopped.' mean? It worked through except the thumbnail? What do you see in the first section in the Photo app (I believe Camera Roll for English iPhones)?

- Harry

[stltri]

There was no error messages. The overlay completed. But video does not have overlay. When I play the video on iPhoto app theres no overlay at all.