length read-only property of the SourceBufferList interface returns the number of SourceBuffer objects in the list.SourceBuffer() getter method of the SourceBufferList interface allows the SourceBuffer objects in the list to be accessed with an array operator (i.e. [].)byteStreamTrackID read-only property of the TrackDefault interface returns the ID of the specific track that the SourceBuffer should apply to.kinds read-only property of the TrackDefault interface returns default kinds for an associated SourceBuffer to use when an initialization segment does not contain label information for a new track.label read-only property of the TrackDefault interface returns the default label for an associated SourceBuffer to use when an initialization segment does not contain label information for a new track.language read-only property of the TrackDefault interface returns a default language for an associated SourceBuffer to use when an initialization segment does not contain language information for a new track.TrackDefault() constructor of the TrackDefault interface constructs and returns a new TrackDefault object.type read-only property of the TrackDefault interface returns the type of track that this SourceBuffer's media segment data relates to (i.e. audio, video, or text track.)