A descriptive, human-readable name for the track.
For example, “Spanish”. This can be used by the sender
UI for example, to create a selection dialog.
If the name is empty the dialog would contain an empty slot.
Identifier of the track’s content. It can be the
URL of the track or any other identifier that
allows the receiver to find the content
(when the track is not inband or included in the manifest).
For example it can be the URL of a vtt file.
The MIME type of the track content. For example
if the track is a vtt file it will be ‘text/vtt’.
This field is needed for out of band tracks,
so it is usually provided if a trackContentId
has also been provided. It is not mandatory
if the receiver has a way to identify the
content from the trackContentId, but recommended.
The track content type, if provided, must be
consistent with the track type.