[MEncoder-users] Encoded DVD video has motion flicker

[Chris Capon]

Hi Laine:

L Lee wrote:
> VLC plays it as is, if that's all you want.

VLC is excellent!  In this case, though, I'm time-shifting TV shows to a 
format useable with a Television.  HD takes a lot of storage so DVD is a 
good compromise and works well with re-writable disks.

> If you want DVD mpeg-2, try this on it. I'm assuming audio won't be a
> problem. I'm using recent mencoder (svn yesterday).
> 
> mencoder cut.mpg -nosound -ovc lavc -lavcopts
> vcodec=mpeg2video:trell:mbd=2:precmp=2:subcmp=2:cmp=2:dia=-10:predia=-10:cbp
> :mv0:vqmin=1:lmin=1:dc=10:vrc_buf_size=1835:vrc_minrate=7500:vbitrate=9000:v
> rc_maxrate=9800:keyint=15:aspect=16/9:vstrict=0 -vf
> tfields=0,tinterlace=0,filmdint=fast=0/sad_thres=2048,softskip,scale=720:480
> ,harddup -noskip -of mpeg -mpegopts format=dvd:tsaf:muxrate=40000  -fps
> 60000/1001 -ofps 24000/1001 -o out.mpg

Cool.  These options eliminate the annoying interlace flicker; but the 
video still suffers from jumpy motion when viewed on a television.  In 
particular it is visible in the scene where the sailboat passes by.  It 
doesn't flow so much as hop.  You don't see that effect when watching 
the source signal.

I wonder if scaling interlaced video has a problem with motion?  For 
instance, if every second line of HD is from a separate frame and you 
scale down to 1/2 the size by combining 2 lines into 1, would some of 
the motion from the second frame be lost?

So, an interlaced image like this:

	..XX....
	..XX....

may look like this in motion:

	..XX....	....XX
	....XX..	..XX..

but scaled to 1/2 size may end up like this:

	.X..		...X

rather than:

	.X..	..X.	...X

(sorry if I'm stating the obvious)

Maybe there is a way to better scale the video while still keeping it 
interlaced?

Thanks for your help and input.  Much appreciated.

Cheers,
Chris.