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Re: [sdw] WebVMT: Review Editor's Draft - Data Model & Syntax

From: François Daoust via GitHub <sysbot+gh@w3.org>
Date: Mon, 19 Nov 2018 15:21:20 +0000
To: public-sdwig@w3.org
Message-ID: <issue_comment.created-439929269-1542640878-sysbot+gh@w3.org>
I'm not entirely clear about design decisions following discussions at TPAC on whether to use WebVTT as:
1. **container format**, WebVMT being a type of WebVTT metadata track,
2. **base format**, WebVMT extending WebVTT, or
3. **placeholder**, pending a generic metadata file format that could perhaps follow a different syntax in the end.

Personally, I would go with 1. to start with and pursue 3., but the current document seems to use 2. I wasn't part of TPAC discussions though!

Sticking to comments that apply in any case:
- I would not duplicate parts already defined in WebVTT. For instance, the definition of a [WebVMT style block](http://w3c.github.io/sdw/proposals/geotagging/webvmt/#dfn-webvmt-style-block) seems to be the exact same one as the definition of a [WebVTT style block](https://w3c.github.io/webvtt/#webvtt-style-block), so I would not duplicate its definition. Or I would clarify somewhere that this is the exact same thing.
- The [WebVMT media definition block](http://w3c.github.io/sdw/proposals/geotagging/webvmt/#dfn-webvmt-media-definition-block) is not specific to maps, does not exist in WebVTT, and yet is defined as mandatory in WebVMT. That seems a good point to discuss with timed text guys if not already done.
- The [WebVMT map definition block](http://w3c.github.io/sdw/proposals/geotagging/webvmt/#dfn-webvmt-media-definition-block) is interesting because the information it contains needs to be exposed to Web applications somehow, and there is no mechanism to do so for now. That is, even if browsers could parse and expose WebVMT cues as DataCue or as a specific VMTCue, the map information would still need to be exposed somehow. I'd raise that as an open issue at least.
- The Spatial Data on the Web Best Practices have [BP 8 - State how coordinate values are encoded](https://www.w3.org/TR/sdw-bp/#bp-crs). I suspect you're only considering WGS 84 here in WebVMT but that is not specified.
- It may be too early to think about this, but I'm not sure how one could extend the format to add additional metadata without risk of collision with future revisions of the specifications. That could be worth considering

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Received on Monday, 19 November 2018 15:21:31 UTC

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