[MEncoder-users] settings to convert ATSC HDTV 1080i30 to 720p24

[Dieter]

> That also depends on the encoder. You'll almost certainly find that every
> frame in 720p is slightly different, even on frames that should be exact
> duplicates. For ABC stations, this is a result on the encoder trying to
> reencode the 45 Mbps network feed into ATSC. I've found that a new frame
> doesn't have as much detail as the "duplicate" frame that follows it. Some
> people have found the opposite.
> 
> Apparently this is because the station's encoder is trying to "keep up"
> with the faster network feed. At 60 fps, your eyes won't notice the
> less-detailed frame after it's been enhanced by the "duplicate" frame.

Occasionally this is visable after a scene change.  I haven't examined
one frame-by-frame to see how many frames the detail enhancement is
spread over, but it is sometimes pretty slow, probably several frames.