[whatwg] Proposal for @label attribute associated with kind=metadata TimedTextTracks

[Eric Winkelman]

Use Case:

Many video streams contain in-band metadata for application signaling, and other uses.  By using this metadata, a web page can synchronize an application with the delivered video, or provide other synchronized services.

An example of this type of metadata is EISS ( http://www.cablelabs.com/specifications/OC-SP-ETV-AM1.0-I06-110128.pdf ) which is used to control applications that are synchronized with a television broadcast.

In general, a media stream can be expected to carry several types of metadata and the types of metadata may vary in time.

Problem:

For in-band metadata tracks, there is neither a standard way to represent the type of metadata in the HTMLTrackElement interface nor is there a standard way to represent multiple different types of metadata tracks.

Proposal:

For TimedTextTracks with kind=metadata the @label attribute should contain a MIME type for the metadata and that a track only contain Cues created from metadata of that MIME type.

This implies that streams with multiple types of metadata require the creation of multiple metadata track objects, one for each MIME type.

Thanks,

Eric Winkelman
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e.winkelman  cablelabs.com
Cable Television Laboratories, Inc.