Deinterlacing needed for resized HD?

[John2002]

When resizing interlaced 1080 HD to something like 704x448 is there any benefit to deinterlacing before resizing, or is that a wasted step? Isn't it the rule you don't need to deinterlace if you are resizing the frame size to half like when you go from interlaced 640x480 to 320x240? Thanks.

[Aktan]

It is not a waste if you ivtc. Then there will be less frames to encode (1/5 less).

[Ark]

Originally posted by John2002
When resizing interlaced 1080 HD to something like 704x448 is there any benefit to deinterlacing before resizing, or is that a wasted step? Isn't it the rule you don't need to deinterlace if you are resizing the frame size to half like when you go from interlaced 640x480 to 320x240? Thanks.

Yes, you can resize without deinterlace first, but you'll get ghosting.
But you can use pointresize() on vertical resolution (and whatever you want on the horizontal),(and if you don't mind some aliasing), to avoid ghosting.

This in fact gives the same result as doing:

Separatefields().Selecteven().pointresize(xxx,height/2)

[scharfis_brain]

you should ALWAYS deinterlace before you're resizing interlaced content.

if your aim is to build a DVD, use this script:


mpeg2source("1080i.d2v")
matchbob() #preserves most detail possible & recognises progressive frames; search the forum
lanczosresize(704,576) #or 704x480 for NTSC
blur(0,0.3) #reduce interlace-flicker
assumebff().separatefields().selectevery(4,1,2).weave() #this produces TFF interlaced