Hero 3 Black user here. Back in the day (i.e. 2017), I used to use GoPro Studio to convert the h.264 .mp4 GoPro footage to .avi using the Cineform AVI codec, and used the .avi clips in Sony/Magix Vegas Pro with no issues. Since abandoning Studio and Cineform, GoPro apparently has no official recommendation for an output codec and/or container to uncompress this footage, and their helpdesk is a total waste of time (had a “tech support” person tell me that my .mp4 footage “needed to be converted to .mp4”). Vegas Pro 18 has issues with unprocessed h.264 footage (stutter/flicker in renders even on a high-powered system with small, single-clip projects with project and render settings inherited from the clip), and their tech support says the issue is with the compressed footage. GoPro's own webpages say "the H.264 file format used in camera is not designed for editing". Transcoding is a bit of a PITA, but it works, and this was GoPro's recommend workflow from day one. There are many other video converters out there (Wondershare, VLC, etc.), but does anyone have a recommendation for an output codec and container for uncompressing h.264 footage from older GoPros to prep footage for use in 3rd-party NLEs (specifically VP18)?