PAL de/interlacing puzzle

[JimmyBarnes]

I rip exclusively PAL DVDs as that's all I can get.

These have all been non-interlaced - until now. The one I have in hand seems "clearly" interlaced. I say "clearly" as I am not absolutely sure - it matches with descriptions of interlacing I have read, what I imagine interlacing looks like. See attached ID.jpg - is this interlacing?

I encoded two 5000 frame clips, one without FastDeinterlace ("VerticalReduceBy2") and one with, from the middle of the movie. They don't look all that different, though the AVIs are clearly not binary identical. The one without deinterlacing doesn't show "interlacing" as does the raw source. Comments??

My question: If a DVD is not interlaced and one applies FastDeinterlace, will that degrade the rip?

Your help appreciated

JB

[chaumurky]

Check this thread:
http://forum.doom9.org/showthread.php?threadid=41608

[N_F]

Originally posted by chaumurky
Check this thread:
http://forum.doom9.org/showthread.php?threadid=41608

Be sure to also check out the thread I make a reference to in the thread chaumurky links to.

[JimmyBarnes]

Thanks for the pointers Chaumurky and N_F.

Hmmm It's more confusing than I ever feared. :(

JB

[manono]

Hi JB-

Yes, that's an interlaced frame (but it may not be an interlaced DVD). You thought that thread was confusing? Gee, I made it as clear as I could. Here's the part that applies to what you need to know:
If it appears to be interlaced, then Load the Decomb Plugin and add Telecide(Post=false) to your .avs. Open it in VDub, find a place where there's movement, and start advancing frame by frame. If you no longer see interlacing, then it just had the common "shifted fields" problem, but if you still see lots of interlacing, then you have an interlaced DVD, and you will have to deinterlace.

If you had the shifted fields that were fixed by adding Telecide(Post=False) to the script, change it for the encoding to Telecide(). This adds the deinterlacer back into it to fix any few interlaced frames that might sneak through.
And if your Fast Deinterlacer is still VerticalReduceBy2, then that means that you should install the new version of GKnot. And using a deinterlacer at any time degrades the resulting .avi, particularly if you don't have to in the first place, and particularly if it's a method that deinterlaces the whole frame (such as VerticalReduceBy2 and the current FastDeinterlacer, SeparateFields().SelectEven().

Edit: I should qualify that last statement. If it's something like FieldDeinterlace(), it kicks in only when it detects combing, and when it does detect combing, it deinterlaces the interlaced portion (leaving untouched the static portions of the frame). So, it's safe usually to use it just to pick up a few interlaced frames that got through IVTC or Force Film.

[JimmyBarnes]

Originally posted by manono
Hi JB-

Yes, that's an interlaced frame (but it may not be an interlaced DVD). You thought that thread was confusing? Gee, I made it as clear as I could. Here's the part that applies to what you need to know:


Actually the part you described above was probably the most helpful in the thread, but further discussion as the thread progressed (and in a related thread) I found hard to comprehend.

According to what you recommended above, my DVD is not interlaced but is field-shifted. So Decomb/Telecide() is what I'll try tonight.

Thanks for your interest

JB

[N_F]

Originally posted by JimmyBarnes
According to what you recommended above, my DVD is not interlaced but is field-shifted. So Decomb/Telecide() is what I'll try tonight.

Not really. It may be fieldshifted, you can't really know until you examine it more closely (according to manono's instructions. Really, as long as you take your time and read carefull they should be quite clear).

[ohliuv]

yea, N_F

I also thought that might be the case. Some time ago I had some time-shifted PAL material.
However, I only remember that there was something important about top-first and bottom-first :confused:

Edit:
now I remember - I used trbarry's GreedyHMA on some dvd extra material

[JimmyBarnes]

Originally posted by N_F
Not really. It may be fieldshifted, you can't really know until you examine it more closely (according to manono's instructions. Really, as long as you take your time and read carefull they should be quite clear).

I did this...

"If it appears to be interlaced, then Load the Decomb Plugin and add Telecide(Post=false) to your .avs. Open it in VDub, find a place where there's movement, and start advancing frame by frame. If you no longer see interlacing, then it just had the common "shifted fields" problem, but if you still see lots of interlacing, then you have an interlaced DVD, and you will have to deinterlace.

If you had the shifted fields that were fixed by adding Telecide(Post=False) to the script, change it for the encoding to Telecide(). This adds the deinterlacer back into it to fix any few interlaced frames that might sneak through."

..to determine that my DVD was fieldshifted.

In the post where I said "Actually the part you described above ..." I omitted the quoted bit above to save space.

I hope I have got it right.

JB

[N_F]

Oh, I got the impression you said your DVD was not interlaced just by reading the instructions. But I guess you did examine the frames before.

What movie is this? I myself have only encountered progressive and pure interlaced PAL movies so far, so I've never seen a field shifted movie yet.