I first rip to MKV via makemkv, I rip it like any other 2d stream. The video file ends up being left/right interleaved.
I then used ffmpeg as documented here https://ffmpeg.org/ffmpeg-filters.html#stereo3d
To separate the left and right channels into sbs file. It ends up with a MKV that is twice as wide as a 2d video steam. I guess maybe my problem is lack of understanding (on my part) of sbs format…
Thanks for testing that. I’ll give the above application a try.