Why WebVMT Branched From WebVTT

> On 22 Jan 2020, at 20:07, Silvia Pfeiffer <silviapfeiffer1@gmail.com> wrote:
> 
> On a side note, why did you have to define a completely new format for the mapping use cases? Want it possible to define a new metadata type for track and reuse webvtt? I'm asking because webvtt was built with the idea of being extensible for all use cases for time aligned data. If there's a limitation to the extensibility, it should get addressed.

Hi Silvia,

Good to hear from you, and thanks for your question.

I initially wanted to make a WebVTT extension, however soon felt that I was trying to bend the format in a completely new direction for the map interface, and beyond its original scope. Text and geotagged metadata share common cue properties, e.g. start time, end time and content, though are presented and rendered in very different ways and places - text versus graphics, video overlay versus map overlay. There's a clear use case for text with video, i.e. subtitles, but metadata use cases are far less well defined, which is reflected in the relative maturities of HTML’s TextTrackCue and DataCue elements.

From a design perspective, I needed new features, e.g. the map block, and found existing ones were unnecessary, e.g. the region block and text formatting features. Having worked on standards' development before, I’m wary of feature creep and was concerned that a combined solution would create an unnecessarily-bloated format which would be complex to implement with minimal overlap between text and geotagged metadata features. Hence, I borrowed the common elements, i.e. cues and the file structure, discarded the text components and added a command structure to make a lean format for WebVMT instead. It may be possible to merge the formats back at a future date, though I still have reservations about this currently.

I’m happy to have a chat with you about this further if you’re interested, and would also welcome your input to the WICG DataCue activity [1] and metadata discussions in Media Timed Events TF [2]. More details about WebVMT can be found at our website [3] and in the Editor’s Draft [4].

I look forward to hearing from you.

Rob Smith

Away Team
www.awayteam.co.uk <http://www.awayteam.co.uk/>

[1] https://github.com/WICG/datacue/ <https://github.com/WICG/datacue/>
[2] https://www.w3.org/2011/webtv/wiki/Main_Page/Media_Timed_Events_TF <https://www.w3.org/2011/webtv/wiki/Main_Page/Media_Timed_Events_TF>
[3] https://webvmt.org/ <https://webvmt.org/>
[4] https://w3c.github.io/sdw/proposals/geotagging/webvmt/
 <https://w3c.github.io/sdw/proposals/geotagging/webvmt/>