[Matroska-devel] New Matroska field: HDR

Steve Lhomme slhomme at matroska.org
Sun Oct 4 16:27:44 CEST 2015


2015-09-23 18:08 GMT+02:00 madshi <madshi at gmail.com>:
> 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.

OK so from what I understand it's just some information to store for
that track. Nothing special other than the codec is outputing wider
range pictures. That property should also be stored (optionally) in
Matroska.

> 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

They talk about a metadata stream, so I assume we need a special track
for that. There is BlockAdditions that was designed for that kind of
things. It may need some improvements though to described the nature
of each addition to the block. Something better than
http://matroska.org/technical/specs/index.html#MaxBlockAdditionID

> 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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-- 
Steve Lhomme
Matroska association Chairman


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