on 05-10-2019 12:30 PM
What I need from this forum, is advice on how to tap into the GPMF data to produce the following array:
I'm not interested in exact precision. I try to note this with a +/- wobble (presuming a base video of 30 fps) in my example. I need this so I can make a map of time/frame for semi-absolue random access to the right image for a given second. Is the GPMF_parser function going to be able to help?
05-11-2019 05:12 PM - edited 05-18-2019 02:23 AM
I think this was discussed here: https://community.gopro.com/t5/GoPro-Metadata-Visualization/Exporting-still-image-with-GPS-coordinat...
But since you don't seem to be interested in GPS locations you might need less than that. You just need the first GPS timestamp, and your framerate.
Edit, you first have to convert your timestamp into a number, I forgot mentioning that. It would take some kind of parsing function, as the format is not a 100% standard.
So, if your numeric timestamp is, for example 1546532061459 and your framerate is 30fps, you can deduce all your data, add 33,333 milliseconds for each frame:
for (let i = 0; i<50; i++) console.log(1546532061459+(1000/30)*i,i+1)
Where the first i<50 is the number of frames you want information on, and the second 1000/30 is based on your framerate.
You can extract the timestamp of the first (and every) frame with these tools: https://tailorandwayne.com/gopro-telemetry-extractor/
For example, choose CSV and do the math in excel or similar, if you want (format the TS column as a number, first).
Note that there might be an offset between the first frame and the first data value. Just now I'm not sure how much that is, you'd have to try tapping the camera and finding those taps both in the video frames and in the accelerometer CSV (create a graph from the data in excel and look for the peak), to calculate the offset.
Hope this is helpful.