[MEncoder-users] Trying to fully understand de-interlacing.

[Grozdan]

On Mon, Jun 28, 2010 at 2:22 AM, Peter <pscientist at inbox.com> wrote:
> I'm the proud owner of a Sony HX5 digital camera, which is "OK" as a "nice"
> camera, but has a movie mode which blows away the competition, at
> 1920x1080/60i which I assume means that it produces fields of 1920x540, 60
> times a second, and that pairs of fields are packaged into frames at 30
> frames per second. (I hope I don't have my fields and frames mixed up.)
>
> I see interlacing as a form of compression which was useful in the days of
> CRT screens, whereby the processing in our eyes would make us think we were
> seeing full resolution, full frame rate, even though only half the data rate
> was required.

It's not a compression. Interlacing is a trick used to reduce
bandwidth in the old days as at that time, bandwidth was very limited.
So if you "split" the image in two (odd and even) and first send the
odd (or even) filed then the even (or odd) field, it will use less
bandwidth compared to sending the whole image at once

>
> I would like to make the best of this interlaced content, without discarding
> either the 60 frames per second, or the 1920x1080 resolution. I want the
> 'impossible' holy grail of making a 1920x1080/60p file out of it. Of course,
> I will then compress the file with H.264, but at that point, I will let
> H.264 do its compression magic in a more appropriate and efficient way than
> the interlacing did.
>
> To let H.264 make the best file, I want it to start with the best data; so I
> want to know how to make yadif create the best stream: neither discarding
> the time data, nor the resolution data, but interpolating the missing data
> in time and space in the same way that our eyes do when watching an old
> interlaced TV.
>
> I realise that this is by no means an easy task. Stationary objects need to
> be interpolated spatially, and moving objects need to be interpolated
> temporally. Can yadif (mcdeint) do that?
>
> I have been reading with interest, the thread "A good compromise for
> deinterlacing camcorder-dv-files" and it looks like yadif pp=ci is the best
> option. Is that right? will it produce a 1920x1080/60p stream?

No, pp=ci will just deinterlace at normal frame rate so you'll get a
progressive image running at 29.970fps

if you want to create 60p (with an fps of 59.940) you have to use a
bobber like yadif=1 (and at your option combine it with mcdeint)

>
> Can anyone suggest a good command line? I have been trying to analyse
> Christian Ebert's suggestion of
> -vf yadif=1,mcdeint=2:1:10,softskip
> against what I take to be the manual at:
> http://www.mplayerhq.hu/DOCS/man/en/mplayer.1.txt
> and it looks like yadif produces 1920x540/60p, and then mcdeint does the
> interpolation with mode=2 (slow) and parity=1 (is that telling it whether
> it's tff or bff?) with qp set to 10. (Quality???)

parity=0 is tff while 1 is bff

qp is for motion vector fields and how "smooth" they are at expense of
individual vectors. Most people use a value of 10

Whether you'll see a (big?) difference between using yadif only and
yadif combined with mcdeint is up for discussion and depends on person
and content. A lot of people don't bother with mcdeint, either because
it's too slow or they can't see the difference between yadif only and
yadif + mcdeint

>
> That manual page has no mention of pp=ci ???

mplayer -pphelp

>
> --
> Peter
>
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