On Fri, 06 May 2011 08:35:42 +0100, Dave Liquorice
wrote:

It's "only" a transcoding
process from MPEG-2 to output it in any digital or analogue format
you desire.

The fact that it's MPEG-2 coded doesn't make it any easier to do the
conversion. Converting frame rates, e.g. 25 to 29.97 or vice versa, has
always been very difficult if you want to maintain a high quality. Even a
second hand 'broadcast quality' standards converter will set you back
around £5,000 (and around ten times that when new).

Not that hard to drop the 96 "extra" lines when going from "PAL" to
"NTSC" be a bit quick 'n dirty but who cares these days...

It's not the *line conversion* that makes it difficult, it's the change in
the frame rate. To achieve smooth motion portrayal it is necessary to
interpolate frames corresponding to intermediate time intervals, and that
involves some kind of Motion Measurement. The best converters use
techniques like Phase Correlation to predict where 'objects' ought to
appear in the output frames.

Richard.
http://www.rtrussell.co.uk/