Re: [Cellar] Adding private elements to Matroska

[hubblec4 <[e-mail]>]

Hi all,


Am 13.04.2018 um 11:35 schrieb Jerome Martinez:
> I am working on a project related to Matroska and I would like to add 
> some private elements to Matroska, at different levels (TrackEntry, 
> BlockGroup, Segment).
> These elements add no specific features for media playback.
>
> As there is no indication about how to add private elements (no 
> element is reserved for hosting private sub elements), Matroska 
> conformance checkers currently flag new elements as "unknown".
>
> I would like to debate about how to add new elements to Matroska, for 
> some specific needs so more flagged "private", and for future needs 
> for Matroska (e.g. HDR metadata was added during CELLAR work, what 
> should be done in the case CELLAR already released the spec?).
>
> Some questions:
> - IMO a new element should not make a new version mandatory, as new 
> element are ignored by players, but what should be the behavior of a 
> conformance checker? error raising if the element is not known, 
> information only? Maybe we need a paragraph about it in specs.
> - How to manage private elements? Difficulty is to be sure an element 
> identifier used by third party A is not reused by third party B due to 
> B not knowing about A.On my side I suggest to just add it to 
> ebml_matroska.xml without specific details in spec itself, see 
> https://github.com/Matroska-Org/matroska-specification/pull/223/files 
> for an example, so everyone is aware of identifiers reserved for a 
> third party tool. Should such elements be in a separate document, 
> mp4ra style?
>
> Jérôme

I have read your PR in Matroska (yet nobody has answered) and it is 
first time reading about RAWcooked. I'm sure there are not much people 
how know about this project.

To add new Matroska elements for this "little" project is in my eyes too 
much. But I can understand how important it is for you and the project.
I wait already a  long time for a PR but It has become quiet around 
Matroska.
When I have more time to work on Matroska Menu I'm afraid it will take a 
lot of time to add new elements.

Then I thought about this problem and maybe is the solution useful.
Inspired by Haali TRACKSETEX which uses the Matroska Tags!

Here my suggestion:

Add a top-level Tag with a SimpleTag with Title RAWCOOKED. Then add for 
all your RAWcooked elements nested-SimpleTags.
In the RAWcooked project is a RawcookedBlockGroupelement(probably very 
often used) which is distributed of the entire file.
To collect all RawcookedBlockGroup values, you must read the entire file 
which takes a while, but with Matroska Tags a reader needs less milli 
seceonds.
You could change all RAWcooked element values without re-muxing the mkv 
file.
You could change the RAWcooked project structure and have also backward 
compatibility.

Every "private" project could add his own Matroska Tags structure. Every 
developer can then decide which projects are supported(Matroska 
reader/Splitter).



For HEVC Hdr data we should add new Matroska elements because this are 
stream base data.


Kind regards
Martin Below