Well it is also not so urgent feature as camera producers provide their solution for that matter (better or worse). The case here is that sometimes default software has some errors in stitching area, or some solutions are platform specific (only Windows, only special mobile device same as camera producer and so on). The case for stills is handled good by Hugin, for video I do not know any open solution for now, but as I have written it is not the most urgent case, probably T9003 is the core of any 360 related tasks.
Some RAW and stitched material can be found on [[https://drive.google.com/open?id=11Aro0uIhJQXMS6sELBdrDBLJqi3AtyhO|Google Disk]].
You may look at projects that handle those subjects:
- tool that integrates a few tools to handle stitching "RAW" data from Samsung Gear360: https://github.com/ultramango/gear360pano
- Tool that blends panorama from couple of sub frames: http://horman.net/multiblend/
- Tool similar to Multiblend: http://enblend.sourceforge.net/
- FFmpeg filter that remaps pixels, useful in such transformatuon: https://trac.ffmpeg.org/wiki/RemapFilter