---TMediaPlayer.Position
Specifies the current position within the currently loaded medium.
property Position: Longint;
Description
The value of Position is specified according to the current time format, which is specified in the TimeFormat property.
Position defaults to the begin
ning of the medium. If the medium supports multiple tracks, Position defaults to the begin
ning of the first track.
----StartPos
----EndPos
自己算算吧。。