On Mon, 20 Sep 2004, Derek Fountain wrote:
> I know my source (from a VCR) is interlaced. I want to play it on a computer
> screen in divx form, which, as far as I can tell, means I should deinterlace
> it. Is that right?
No, not really. Leave it interlaced on the encoding side of things.
If desired you can deinterlace on _playback_ (xine, vlc, mplayer, etc
all offer that capability). "divx" is MPEG-4 and I recall no
restriction in the MPEG-4 specs against interlacing...
> Well, I do have an interlaced source, so this tells me I can go either way,
> but if I deinterlace I will lose details. OK. Two sentences later the HOWTO
Yes indeed. And what's more the process can't be undone - you're
stuck with a lossy (possibly blurred) encoding.
> says "If you only want to play it back on the Monitor (progressive display)
> the picture looks better when playing it back if it is deinterlaced." Which
> appears to contradict what is said above: deinterlacing looses details, but
> looks better when playing it back?
By looking better all that was meant was that you don't see the
hair-comb effect during scenes with motion. That's all.
> > When you record from a VCR at halfe size, you have no interlacing. So
> > you do not need to think about that.
>
> OK, at least that's easy! :o)
Yep ;) For VCD (352x288 for "PAL", 352x240 for "NTSC") and MPEG-1
it's all progressive (but at half the spatial resolution of full
frame of course - it may be deinterlaced but there's only 1/2 the
detail present).
> Er, yes, those are my choices - deinterlace or leave it interlaced! That
Leave it interlaced and do the deinterlacing at playback time.
> more but it's a painful process with an old PC.
Hmmm, and I thought I was a masochist using 800MHz P3 systems :)
Actually I have used 550MHz systems but thankfully it was a quad
cpu setup - which helped (but was still a dreadfully slow affair).
> I can ask one straight question though, which might attract a straight answer:
> will the denoise process run faster on a deinterlaced stream or an interlaced
> one?
Nope - it's the same amount of data, the only difference being how
the rows of data are examined/searched.
'night.
Cheers,
Steven Schultz
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