Scene based HDR Metadata smpte 2094 ?

[superkraft]

Hello Doom9 forum - here my first post :)

For encoding HDR10 (SMPTE ST 2086 ) material there is the SEI information available which can be added in the encoding process (maxfall, maxcll, WP, ...).


But for HDR10+, which is defining a dynamic approach how is this metadata written ?
The ST 2094 approach is scene(time-) based, so therefore there should be something like a table with those informations and their changes in time...

How is this metadata stored?
Which encoder can deal with this right now?
Which workflow appears suitable?

THX!!!

[superkraft]

For the ones interested here an overview by Lars Borg on youtube:

The ST 2094 Standards Suite For Dynamic Metadata
https://www.youtube.com/watch?v=qicgLruwMTY

The technical approaches to the implementations are explained, but I would be rather interested in the practical implementation.

[sneaker_ger]

HDR10+ is also stored in SEI messages. SEI messages aren't (necessarily) valid for a whole stream but can be attached to single GOPs and even frames. (Quite on the contrary, often SEIs have to be repeated because they become invalid at e.g. a keyframe.) So you can put different HDR metadata into different parts of a movie.

x265 allows this but I have never done it myself.
http://x265.readthedocs.io/en/default/cli.html#cmdoption-dhdr10-info

[superkraft]

Thanks Sneaker_ger for this reply!

Please excuse if this appears a bit naive:

From a practical point of view:
In the st 2086 process, I tell the encoder how the settings should be - but I do this exactly once: For example in ffmpeg I would attach that information in the command line as additional parameters.

But how would that work with st 2094 - so time-based? I imagine something like a text file, which includes a table for time and SEI.
I imagine a file similar to an .srt file for subtitles:
But instead this information is probably integrated directly into the stream with infos for time-range and maxcll / maxfall / wp)

How do I tell an encoder to implement all this information?
And how do I store this information for each scene?

[MGarret]

There is a sample JSON file in the link sneaker gave you (--dhdr10-info <filename>) as well as pdf with syntax of metadata file. Other than that, maybe ask in the x265 thread for additional info.

[foxyshadis]

Thanks Sneaker_ger for this reply!

Please excuse if this appears a bit naive:

From a practical point of view:
In the st 2086 process, I tell the encoder how the settings should be - but I do this exactly once: For example in ffmpeg I would attach that information in the command line as additional parameters.

But how would that work with st 2094 - so time-based? I imagine something like a text file, which includes a table for time and SEI.
I imagine a file similar to an .srt file for subtitles:
But instead this information is probably integrated directly into the stream with infos for time-range and maxcll / maxfall / wp)

How do I tell an encoder to implement all this information?
And how do I store this information for each scene?

That's entirely encoder-dependent. x265 has a fairly well-documented JSON format that you can pass, but no other encoder supports it; each has their own method. You can also insert your SEI messages after the fact, but I don't know of a ready-made tool that does so right now.

[kolak]

Resolve Studio with HDR10+ option can export xml with metadata, but no idea if this is 100% compatible with x265 format.