[webvtt] Wide Review Comment 2017: Timing

nigelmegitt has just created a new issue for https://github.com/w3c/webvtt:

== Wide Review Comment 2017: Timing ==
Copy/paste from https://lists.w3.org/Archives/Public/public-tt/2017Sep/0080.html - raising as an issue for tracking/disposition purposes.

WebVTT timing does not specify the time base that applies, except by reference to HTML5.1 media timelines. In general it is assumed to be media time, i.e. The first frame of the video is time zero. That makes sense in relation to a distributed piece of media such as would be present in an HTML video track. However there are broadcast usages of subtitle files that need to relate times to embedded timecode in video. It may be that such practices are phased out over time; until that occurs however, there is no defined data structure in WebVTT (even as metadata) that allows the processor to understand how to relate timestamps to the media with which the file is somehow associated, or indeed how the timestamps were generated. 

For example, if a WebVTT file were authored against embedded timecode timestamps, but then that file were accidentally re-used against video media stripped of such timestamps, the content would display at the wrong time, but there would be no information available within the WebVTT file to identify that such a scenario had occurred.

Please view or discuss this issue at https://github.com/w3c/webvtt/issues/369 using your GitHub account

Received on Wednesday, 27 September 2017 11:02:08 UTC