[MEncoder-users] converting a 59.940 FPS avi into a 23.976 FPS one

[D Richard Felker III]

On Tue, Feb 01, 2005 at 06:25:03PM -0800, Trent Piepho wrote:
> On Sat, 29 Jan 2005, D Richard Felker III wrote:
> > > > well first of all we need to know more about the source. this is very
> > > > strange source. is it really 60 (59.94) distinct, progressive frames
> > > 
> > > It's not that strange at all.  It's what ABC broadcasts all day long when they
> > > don't have native HD content.  It's NTSC upconverted from 480i-60000/1001 to
> > > 720p-60000/1001.  It could be telecined, but probably isn't.  
> > 
> > ok, then encoding at 29.97 (30000/1001) fps will do fine, i expect.
> 
> That's a sub-optimal way to encode it.
> 
> The proper thing to do depends on the original source, is it 60 fps or 24 fps? 
> I'm omitting the factor of 1000/1001 for the sake of brevity.
> 
> A 60 fps source is something shot on video as opposed to film, like a low
> budget tv shot, the news, sports, porn, etc.  In this case think of the
> original video as 640x240 frames at 60 fps.  The TV station up-converts each
> frame from 620x240 to 1280x720 by adding black bars to the sides and scaling. 
> If you want to encode this properly, you should scale the height down by a
> factor of 2 (relative to the width) and encode as an interlaced sequence at
> 30fps.  mpeg1 doesn't support interlaced sequences, while mpeg2 does.  I don't
> know about other codecs.

what?!?!?! why? if the video is already nice 60 fps progressive, just
leave it that way. interlacing it is ruining what you've got..

rich