Yeah it’s individual JPEG2000 images, which is definitely...a way to do it.

My prosumer cinema camera (sigma fp) records video with individual dng files and a wav for audio. I think it’s not that unusual.

I would imagine a big advantage for the production team is being able to screen it and pause on any single frame and have it be perfect - consumer codecs all seem to use keyframes, which certainly save a lot of space, but if you start on a non-keyframe you either get no output or pixel puke until the next one.

They mark which frames they're referring to, so you at most just get a little stutter to decode those other frames if you're optimizing for the scrubber use case.

Not sure how much benefit there is in h265 over h264 or something like j2k at high bitrates, at low rates h265 certainly is beneficial.

Either way 500GB for 2 hours is still significantly compressed - over 90%.

Standard UHD 10 bit 30 bits a pixel, even at just 24fps is 384021603024 = 6gbit/sec just for the video alone without audio, ancillary information, and container overhead. I suspect movies work in 12 bit too, and work at 4k, so that's 409621603624 = 7.7gbit/second, or about 7TB for a 2 hour movie.

Were movies ever displayed at this bitrate in regular theaters?

My understanding is that it isn't even used in the cameras. It's compressed, at the very least losslessly, immediately.

ah yes, having to store 6 gbit/s on a (somewhat) portable device is best avoided.