segmentMetadata is metadata that applies to a specified time range. Specifies the inclusive start time of the period to which this metadata applies. Specifies the length of the period in milliseconds. Specifies the inclusive start time of the period for this list. If omitted, defaults the startTime of the first temporalMediaMetadata element. Specifies the length of the period of this list in milliseconds. If omitted, defaults the duration between startTime and the last elment's end time. A chronologically ordered list of segmentMetadata elements