Last weekend I did a training session on the bike on a race track. Obviously the Virb Elite GPS resulted in very fluctuating speed data due to the poor GPS reception indoor, so that data is not really useful for the overlays I want to use in the resulting video.
However, I also had my Edge 500 on the bike that was paired with my speed/cadence sensor. (don't ask me why I didn't pair the Virb with it too...). Now, due to my second bad choice, I turned off the GPS in my Edge 500 (as I was indoor and wouldn't use it anyway, just wanted the sensor data) so the resulting FIT files do not contain any position data, only the speed/cadence/temp/distance/time data.
Now, I tried to import the .fit from my Edge to create the overlays. But. Virb Edit complain that the file do not include valid data and mention something about missing timestamps. Now, I do understand that Virb Edit need timestamps to be able to match the data against the video. But the .fit from my Edge do indeed contain valid timestamps. If I dump the .fit data this is what the records look like:
Local message type: 5 (message name: record, message number: 20)
timestamp (253-1-UINT32): 2014-02-15T13:59:47 (761403587)
distance (5-1-UINT32): 10134.51m (1013451)
altitude (2-1-UINT16): 163.6m (3318)
speed (6-1-UINT16): 29.520km/h (8200)
heart_rate (3-1-UINT8): 156bpm (156)
cadence (4-1-UINT8): 77rpm (77)
temperature (13-1-SINT8): 18deg.C (18)
So, in my mind this should be perfectly useful to add sensor data overlays to my movies. In this case I do not need any GPS track, but still want to know my speed and pulse. My guess is that Virb Edit actually require position data as well? But as long as there is a valid timestamp I can't see why that would be required when there are other values in there that can be used.
(of course I could have left the GPS in my Edge enabled and I would be all set. Unfortunately it is a bit difficult to do after the fact ;)
I have also tried to convert the fit to valid GPX Virb Edit can import. But all converters I have found produce an "empty" gpx as there's no position data available. Also if I try to fake position data, the GPX will not be very useful as that format do not contain speed values, it calculates the speed from the position data, so I'd have to recreate the correct lat/lon relative values for each datapoint, which is a bit too much work for this little project ;)
Any chance we'll be able to use such a file, with sensor data and valid timestamps but no GPS track, for the overlays in the future?
/Thomas
