GKnot and deinterlacing

[Scandinavian]

I post this in the Newbie-section because I feel it might be a stupid question.

I have difficulties to understand which are the correct settings for deinterlacing in GKnot. I read around in the forums but have not really seen the light so far. I am doing almost only PAL videos.

The dvd2avi-guide sais this:
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Frame Rate = 25.000 fps: your source is PAL. If the frame type is Interlaced, start the preview again and watch closely if you see no horizontal black lines going through the picture then the frames are actually progressive and you're already done here. If there are such black lines, try changing the field order by selecting Video - Field Operation - Swap Field Order and run the preview again. If you can still see horizontal lines reset the Field Operation to None, otherwise leave it as it is.
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I actually never observed black lines. Does this mean that I should not tick a deinterlacing filter when encoding later?

The Gknot-guide sais:
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If DVD2AVI showed your source as interlaced PAL and the preview was interlaced you enable Separate Fields here.
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When I didn't see any black lines is it then interlaced or not and should I enable "seperate fields" when encoding?

As a matter of fact I never ticked any deinterlacing-options when encoding. (I did a 20 or so films, most of which have been fine.)

Thanks for having patience with newbies... :-)

Scandinavian

[jggimi]

No problem, Scandanavian. Good question, as PAL discs are often conversions from NTSC, sometimes causing special problems. Sometimes.

I recommend reading Hakko's comments directed at PAL users in the IVTC Tutorial. Most of the tutorial is about NTSC, but Hakko, being from Sweden, has had his share of all different types of PAL transfers. He separates them into 3 classifications, "The Good, the Bad, and the Ugly." www.doom9.org/ivtc-tut.htm.

[Scandinavian]

Thanks jggimi! I read and tried to digest the tutorial you and Hakko wrote. I experimented a bit with "Erin Brockovich" (PAL version) during the weekend. DVD2AVI sais in the preview that it is interlaced. I could not see the fine black lines the Gknot-guide talks about. I endcoded a version with "field deinterlaced" and a version without. However I could not see any difference between the two encodes. Is that normal?

[jggimi]

Your disc probably falls within what Hakko calls "The Good."

Don Graft's Field Deinterlacer will only change frames where interlacing artifacts exist, and only those areas of the frame with artifacts. It's slower than encoding without it, but it does no harm, as far as I can tell, on progressive frames that happen to by flagged as interlaced in MPEG-2.

[hakko504]

Originally posted by jggimi
Your disc probably falls within what Hakko calls "The Good."

Don Graft's Field Deinterlacer will only change frames where interlacing artifacts exist, and only those areas of the frame with artifacts. It's slower than encoding without it, but it does no harm, as far as I can tell, on progressive frames that happen to by flagged as interlaced in MPEG-2. ... but it may falsely flag some frames as interlaced and thus deinterlace them. 'Erin Brockovich' is a movie original, and the only form of deinterlacing that should be used on those sources is Telecide(post=false,guide=2). In this case as you say you can't see any difference you may leave out all forms of deinterlacing.

Edit: And before you ask, no I haven't encoded Erin Brockovich and I most likely won't.

[jggimi]

Thanks for the correction/clarification, Hakko!

[Scandinavian]

Thanks to both of you. I feel I understand the subject a little bit better now. Maybe the right strategy on PAL videos is not to deinterlace unless one "sees" that its neccessary because of lines, artefacts etc.

[hakko504]

Originally posted by Scandinavian
Thanks to both of you.You're welcome
Maybe the right strategy on PAL videos is not to deinterlace unless one "sees" that its neccessary because of lines, artefacts etc. Exactly.