[Matroska-devel] New Matroska field: HDR

madshi madshi at gmail.com
Wed Sep 23 18:08:36 CEST 2015


2015-09-23 17:50 GMT+02:00 Steve Lhomme <slhomme at matroska.org>:
> Technically it works using a side channel that's transmitted to your
> TV over HDMI. I don't know why it's not part of the original decoded
> video frame, but what do I know...

Actually, it depends on the HDR standard, AFAIK.

The UHD Blu-Ray default is SMPTE 2084/2086, which means video is
encoded with a different transfer function. In that case HDR is part
of the transfer function and there's no side channel, other than some
metadata which tells us the gamut and min/max luminance capabilities
of the mastering display.

Dolby Vision HDR is a different story, and optionally also supported
by UHD Blu-Ray. Dolby Vision HDR uses the same SMPTE 2084 transfer
function, but also allows a side stream (Dolby calls it "enhancement
layer") which then ups the bitdepth compared to the base video stream.
See here:

http://www.dolby.com/us/en/technologies/dolby-vision/dolby-vision-white-paper.pdf

So depending on the HDR standard there may be a side stream, maybe
also additional metadata, maybe even metadata per frame (I don't
know). But there is also going to be HDR content without any side
streams and with just one metadata block per movie.

Best regards, Mathias.


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