[mythtv] DVD playback - average length of a VOBU? (related to ticket #4492)

[Martin Long(myth)]

>
> 1Hz - 2x
> 2Hz - 4x
> 3Hz - 6x  etc
>

Note the deliberate mistake, in that I didn't account for the time the
video plays (although, does it only show frozen frames?).

1Hz - 3x
2Hz - 5x
3Hz - 7x