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Add requirements to VideoFrame metadata registry definition #597

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Nov 15, 2022
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Add requirements to VideoFrame metadata registry definition #597

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Add requirements to metadata registry definition
chrisn Oct 21, 2022
4a000c7
Clarify metadata entry requirements
chrisn Oct 24, 2022
409ada0
Clarify metadata entry requirements
chrisn Oct 24, 2022
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17 changes: 13 additions & 4 deletions video_frame_metadata_registry.src.html
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Expand Up @@ -30,21 +30,30 @@
Registration Entry Requirements {#registration-entry-requirements}
==================================================================

A registration entry is a document describing one or several metadata entry,
A registration entry is a document describing one or several metadata entries,
and has the following requirements:
1. Each metadata entry is defined as a separate {{VideoFrameMetadata}}
dictionary member.
2. Each metadata entry must be serializable.
3. Each metadata must be defined by a W3C specification and have clearly defined semantics.
In particular, its interactions with the media processing pipeline
3. Each metadata entry must be defined by a W3C specification that has
reached consensus in the originating Working Group.
Comment on lines +38 to +39
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@tidoust tidoust Oct 25, 2022

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Three questions:

  1. Does this need to be restricted to W3C specifications?
  2. Should this be restricted to normative specifications?
  3. What does it mean for a W3C specification to have "reached consensus in the originitaing Working Group"?

For 1., I realize that it's hard to come up with an explicit set of requirements for a specification to be considered good enough. A document that comes to mind are the considerations the Director takes into account when evaluating normative references from W3C documents. These considerations include considerations such as:

For 2., I'm wondering whether the group is ok with specifications on the Note track, as done for codec registrations but perhaps not such a good example to follow?

For 3., a status on the Recommendation track (e.g. Candidate Recommendation), would make things clearer. Also, I'm thinking that the group might want to add entries even when a spec is still under development?

I'm having a hard time coming up with a proposal that is not convoluted, so perhaps it's fine to leave this a bit under specified. If the group wanted to open the registry to non-W3C specs, the following wording could be considered:

Suggested change
3. Each metadata entry must be defined by a W3C specification that has
reached consensus in the originating Working Group.
3. Each metadata entry must be defined in an established standard with licensing terms that are consistent with royalty-free implementation of W3C Recommendations. The Media Working Group will evaluate candidate specifications following [considerations used when evaluating normative references from W3C specifications](https://www.w3.org/2013/09/normative-references) [[NORMATIVE-REFERENCES]].

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@chrisn chrisn Oct 27, 2022

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Thanks @tidoust, my thoughts on your questions:

  1. We discussed limiting to W3C specifications in [WebCodecs VideoFrame metadata registry] Introduce VideoFrame metadata #559 (comment), my interpretation is partly as a way to ensure compatible licensing
  2. My understanding is that metadata entries should be normative, but they may be optional to implement, per [WebCodecs VideoFrame metadata registry] Introduce VideoFrame metadata #559 (comment)
  3. I expect that we will want to add entries in draft state. I saw consensus here as: Media WG having consensus to add the registration, and the originating WG having a draft spec to add and consensus on its purpose and scope, it's OK if details are still in development ([WebCodecs VideoFrame metadata registry] Introduce VideoFrame metadata #559 (review))

4. The specification defining each metadata entry must provide clearly defined
semantics. In particular, interactions with the media processing pipeline
(encoders, decoders, renderers, etc.) should be well defined.
4. A candidate registration entry must be announced by filing an issue in the
5. A candidate registration entry must be announced by filing an issue in the
WebCodecs GitHub issue tracker so they can be discussed and evaluated for
compliance before being added to the registry. If the Media Working Group
reaches consensus to accept the candidate, a pull request should be drafted
(either by editors or by the party requesting the candidate registration)
to register the candidate. The registry editors will review and merge the
pull request.
6. Existing entries may be changed after being published, through the same
process as candidate entries. Possible changes include modification of
the link to the public specification.
7. Existing entries may be deprecated. This requires Media Working Group
consensus, and if still active, consensus of the Working Group that
originated the registration entry specification.


VideoFrameMetadata definition {#videoframemetadata-definition}
=============================================================
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