Re: [Mjpeg-developer] Is "mpeg2enc -p" doing 3-2 pulldown correctly?

[Steven M. S. <sms@2BSD.COM>]

On Sun, 27 Feb 2005, Steven Boswell II wrote:

> >up/down/up/up is one group of 4 frames and
> >down/up/down/down is another - 3:2 pulldown is a
> >4 -> 5 frame conversion so that makes sense.
> 
> But then shouldn't the pattern happen every 5
> displayed frames?

	Maybe, maybe not.  THe hunch/thought I had was perhaps the 3:2 pulldown
	removal was causing the problem - 5 going into 4 incorrectly.  Then
	later on when the encoder adds the 3:2 pulldown back in it's doing so
	with frames that have the fields out of order 

	Or something like that ;)

> Well, it's every _film sourced_ LaserDisc.  The
> LaserDiscs whose original video was interlaced

	Non-film based sources don't need to be processed thru a 3:2 pulldown
	removal so they'll work/look fine.

> I also don't see it on VideoCDs of converted film --
> there, 23.97fps is an accepted frame rate and so no 3-2
> pulldown is done.

	And VideoCDs only use 1/2 the information - a single field progressive,
	so there's no chance to get the fields mixed up ;)

> Also, I had field-order problems a few times
> recently, and the artifact was obvious, both on
> the TV and on the computer monitor; it looked like

	I've had cases, not recently, where playback on a computer screen
	looked perfect and the field reversal problem only showed up when
	playing the disc with a settop box and a TV set...

	Cheers,
	Steven Schultz