Interlaced, progressive once more

[Megawarp]

I spent many time reading about this issue in doom9 forum, but I have got lost somewhere. I live is PAL land, I never had an NTSC DVD. As many people before me also posted many PAL DVDs witch appear in DGindex progressive are flagged as interlaced. Reading throw the posts If I undestand correctly it is possible that a progressive material, witch in DG index looks progressive, is encoded as interlaced, (the original stream is stored in interlaced structure) so it should be treated as interlaced (Scan type: alternat, Frame type: interlaced). But if its true, how can I make use of the disable interlaced option, I mean how can I really tell if something looks totally progressive in DGindex, that it is truly progressive and flagged by mistake or whatsoever as interlaced, or it is progressive, but encoded as interlaced.

So the bottom line of my question is, that if I check the DVD in DG index, and it looks progressive, but according to DGindex (or Bitrate Viewer) it is flagged as interlaced, can I use the disable interlaced option in DVDRB, or not, because may be the original stream is stored in interlaced structure, and interlaced true should be used.

For any help thanks in advance!

[Susana]

the only way is looking at the picture. What I do is import a vob in virtualdubmod and look carefully

[Megawarp]

Hi Susana and thank you for the quick replay! Checking out the picture is OK, I use DGindex to do it. But I found threads dealing with the problem the a original stream
witch looks progressive can be encoded as interlaced, so you should also encode it as interlaced. The last thread was this sticky one I browsed, may be I misunderstood something:
http://forum.doom9.org/showthread.php?t=70225

[Susana]

just to check things i was wondering it this is correct:


AVISynth Script (look for interlacing artifacts with DVD2AVI or VDubMod)

Progressive - ConvertToYUY2()
Interlaced - ConvertToYUY2(interlaced=true)
If in doubt or int & prog - ConvertToYUY2(interlaced=true)


CCE Settings

Progressive - Progressive Frames: On, Scan Order: ZigZag
Interlaced - Progressive Frames: Off, Scan Order: Alternate


That seems to keep the picture fine for both types

That was the conclusion, unplugged didn't agree, though.

In my opinion, the conclusion is right (it's what Rebuilder does): a progressive picture is progressive by nature; if it is encoded as interlaced, there is some error between consecutive lines, and this error is increased if encoded as interlaced again.

Thanks RB, that makes me feel better. Well, at least it did.

I (finally) replicated unplugged's experiment on an interlaced/zigzag PAL DVD and skipped to a red area. The results, to my eyes, appeared better with interlaced=false.

Specifically, in the top left corner of the picture where the red met the black border, there are clear lines showing in the transition area when interlaced=true is used. [This is with 300 percent zoom, obviously]. The same problem is there as the red moves along the top edge (it's a person's hat).

I have 2 psd screenshots (1.7 MB compressed) that I can provide on request (I have webspace). Just open in photoshop and zoom in :/

edit: just tried it with an interlaced/alternate source (Chicago R4), and noticed the same phenomenon, this time with blue against the black border, as well as red against the black border.

Also, noticed for the "main" picture that blue edges against a black background and red edges against black backround clearly looked better with interlaced=false.

I don't know what unplugged saw; I've not done this experiment myself.

Anyway, its worse to encode as progressive a interlaced source.

[Megawarp]

Thanks for the replay again! I went throw that post again and again just now. My native language is not english, and the technical staff just makes it worse, but I think there are inconsistency in the thread, which makes me question this statement.

Originally Posted by burnout
just to check things i was wondering it this is correct:


AVISynth Script (look for interlacing artifacts with DVD2AVI or VDubMod)

Progressive - ConvertToYUY2()
Interlaced - ConvertToYUY2(interlaced=true)
If in doubt or int & prog - ConvertToYUY2(interlaced=true)


CCE Settings

Progressive - Progressive Frames: On, Scan Order: ZigZag
Interlaced - Progressive Frames: Off, Scan Order: Alternate


That seems to keep the picture fine for both types

Well, I keep searching through the forum, maybe I find something that answers my question, but I would really like Jdobbs input on this! (But he's probably fed up with questions about this interlaced and progressive staff :))

[fjhdavid]

honestly, I have many PAL DVD (progressive and intelaced), and I am not able to see the difference betwen the interlaced=true or interlaced=false statement (in the filters choice)!

even if you take pictures (with powerDVD for exemple) of the target film (after re-encoding) and see side by side the two pictures (intelaced or not), I am not able to see the difference...so imagine when you are wtaching the film...

[smok3]

avisource("film.avi")
# open this and see if the motion is progresing to determine if
# field order is bottom first, or top first
bottom = AssumeBFF().SeparateFields()
top = AssumeTFF().SeparateFields()
bottom = subtitle(bottom, "BFF - bottom field first")
top = subtitle(top, "TFF - top field first")
StackVertical(top, bottom)

[fjhdavid]

yes it is true if you are just at just at 5inch from the screen and are very careful (so you don't watch the film anymore) and there is a lot of motion, you can see sometimes, that the progressive film stored on the DVD was badly recorded interlaced...

but anyway this script is intresting, thank you. even if they are very small, differences still exist.

[Megawarp]

Hello! Fjhdavid thank you for responding, actually I can't notice any difference either, may be I'm not looking where I should, or may be it's my display. My original question was, that is it possible that a source witch in Dgindex, or Virtualdubmod looks perfectly progressive, but it is encoded as interlaced, so one should encode it as interlaced.

smok3 with this script can you determine this?

[smok3]

you can determine field order, open script in virtualdub and progress frame by frame, if there is jumping in time in one of the windows then field order is the other one, if there is no jumpering in time in both windows, then the source is progressive (or should i say, part of the source you are looking at).

p.s. if it is flaged as interlaced, that does not mean you should encode it as interlaced.

p.s.2. anyway interlaced stuff is easy to detect by just dropping file into vdub and find a frame with some motion, example;
http://somestuff.org/Noname.jpg
(yes this is interlaced)

[Megawarp]

Thanks for the answer smok3, but I am unable to open it. How can I do it?

[smok3]

try
http://fcchandler.home.comcast.net/~fcchandler/Plugins/MPEG2/index.html

[Megawarp]

Thanks again! I managed to open the MPEG2, but how I open the script?

[smok3]

i have mentioned two methods;

1st: dump the thing into virtualdub (you can quickly determine if interlaced is true/false)

2nd: use avisynth script to determine the same and also field order (about avisynth: www.avisynth.org, the good old method for opening mpeg2 stuff is via dgindex plugin, do some searches on the subject..)

dgindex http://neuron2.net/dgmpgdec/dgmpgdec.html

[Xoote]

thanks for the info

[Megawarp]

OK smok3, thanks again, I do some more researche, than I try it!