the format of the segment.
the running_time in the segment
the position in the segment for @running_time. This function returns -1 when @running_time is -1 or when it is not inside @segment.
Deprecated: Use gst_segment_position_from_running_time() instead.
Convert @running_time into a position in the segment so that gst_segment_to_running_time() with that position returns @running_time.