* @timestamp: (out) (allow-none): location where to store the
* start time (pts) of the gap, or %NULL
* @duration: (out) (allow-none): location where to store the duration of
* @timestamp: (out) (allow-none): location where to store the
* start time (pts) of the gap, or %NULL
* @duration: (out) (allow-none): location where to store the duration of