[arch1t3cht]

HDR is nothing more than metadata about the color spaces. The way the underlying pixel data is encoded does not change. HDR consists of

1. A larger color space, allowing for more colors (through different color primaries) and a higher brightness range (though a different gamma function)

2. Metadata (either static or per-scene or per-frame) like a scene's peak brightness concrete tonemapping settinsg, which can help players and displays map the video's colors to the set of colors it can display.

I actually have a more advanced but more compact "list of resources" on video stuff in another gist; that has a section on color spaces and HDR:

https://gist.github.com/arch1t3cht/ef5ec3fe0e2e8ae58fcbae903...