This function will be called whenever the current clock time needs to be calculated. If this function returns #GST_CLOCK_TIME_NONE, the last reported time will be returned by the clock.
the current time or #GST_CLOCK_TIME_NONE if the previous time should be used.
This function will be called whenever the current clock time needs to be calculated. If this function returns #GST_CLOCK_TIME_NONE, the last reported time will be returned by the clock.