[Discussion] Use of GPX file, joining files, multiple recordings

[tve]

I was thinking a bit on what I would need to be able to use gopro-overlay for my use case. My outings are 1-2 hours long and at the moment I'm turning the camera on/off 'cause the battery only lasts an hour or so. In the end, I may want to watch almost the whole recording for myself with overlay, but I really want to produce a 3-10 minute collage of highlights. So, what I've observed:

• I want an overview map with the red "current position" dot to be based on the entire gpx file, 'cause I want it to show my entire route regardless of what segment I may run gopro-overlay on
• I generally have a garmin gpx file, but it would be handy to export the data from the gopro mp4's if I don't (export for the previous point to work), for that I would need a command that accepts all mp4 files and produces an aggregate gpx (if I turn the camera off and on there will be some straight-line segments across the gaps, which is OK)
• I would like to be able to run gopro-overlay on the whole thing, but using gopro-join takes forever and uses a ton of disk space, it would be much better if gopro-overlay could do the concatenation on the fly (it's "just" a matter of producing the right ffmpeg commandline -- haha, I know...)

Does this sound reasonable? I'm not expecting you to implement everything, I can pitch in too, just want to hear whether this matches others' use-cases too.

[time4tea]

Thanks for your thoughts... if you concatenated the GPX files for the various short trips, then the existing code would work almost without change - just would need to not crop the GPX file to the movie, which is easy.
Not sure of the exact command line sequences, but should be do-able.

[thereticle]

If I were to run the ffmpeg command by hand, what is the ffmpeg command for chaining two consecutive but detached videos (I stopped recording and restarted it) without losing telemetry data? I tried to figure it out by examining the ffmpeg.py file and made several attempts, but without success (unfortunately I'm not very experienced).

[time4tea]

Based on a few issues raised with joining MP4s and preserving the metadata, I'm going to look into how this might be done.

[paxunix]

It is possible to use exiftool to extract a cumulative GPX file across multiple source MP4s. Presumably, you can feed that GPX to gopro-overlay. (Forgive my ignorance that I'm not currently aware if the GPX data "stream" will take precedence over the MP4 telemetry stream--I guess in my ideal universe, I can have multiple sources of telemetry and pick and choose amongst them). It seems like all the pieces are available, just need to be glued together suitably.

[time4tea]

I realise not much has happened on this thread for a while... but I'm doing some refactoring that should mean that we can get some movement on this....