SoundheadPreroll
Position of Soundhead after loading of elements:
* -1
Soundhead is positioned on MarkIn of first element. If MarkIn is not visible the soundhead is set to the left window border.
* 0
Soundhead is positioned on MarkOut of first element.
* 5
Soundhead is positioned 5 seconds left of the MarkOut of the first element. If the position is not in the visible area, the soundhead is set to the left window border.
* 60
Soundhead is positioned 60 seconds left of the MarkOut of the first element. If the position is not in the visible area, the soundhead is set to the left window border. If the element is shorter than 60 seconds, the soundhead is set to the MarkIn if visible.
Possible values: -1...86400
Default value: -1