Deinterlace? No to Deinterlace?

[0verd0ze]

Hey, got this dvd ... and going through dgindex i got this info ..

FPS: 29.970
Video Type: Video 1%(Film 99%)
Frame Type: Progressive

first of all , dont know if i should deinterlace or not ?

and the second thing is that i dont know if i should pick 23.976 (FILM) or 29.970(NTSC) in vdubmod ?

[LoRd_MuldeR]

If it is "progressive" then you don't need to deinterlace it. It will only make quality worse and take time for nothing. Nevertheless if you see any combing artifacts, then it is interlaced and needs deinterlacing.

[0verd0ze]

If it is "progressive" then you don't need to deinterlace it. It will only make quality worse and take time for nothing. Nevertheless if you see any combing artifacts, then it is interlaced and needs deinterlacing.

Well i can see the ghostframes , and those lines that significate interlaced source .. soo

[Guest]

It's probably soft telecined if DGIndex say 99% film.

Try using Forced Film in DGIndex and see what happens. Probably that's all you need to do. You wouldn't deinterlace this.

[0verd0ze]

It's probably soft telecined if DGIndex say 99% film.

Try using Forced Film in DGIndex and see what happens. Probably that's all you need to do. You wouldn't deinterlace this.



sooo ... i did the "forced film" step ... and the frame type jumps between progessive and interlace .. and now its 23 fps ... which makes it look awesome :P .. soo all i need to do is force film and then encode it without the deinterlace step ...

btw what does "forced film" do in dgindex ?

[LoRd_MuldeR]

btw what does "forced film" do in dgindex ?


From the DGIndex manual :rolleyes:

Force Film - This option is intended for the special case of film content encoded at 23.976 fps but pulled down for display at 29.97 fps, i.e., 3:2 pulldown. This option will restore the 23.976 fps film rate while keeping audio and video in sync throughout the clip. This option works by ignoring pulldown flags and inserting/removing frames to maintain a constant and sync'ed output stream. Do not use this option on non-3:2 pulled-down material, and, therefore, never use it on PAL or MPEG1.

[Guest]

the frame type jumps between progessive and interlace Don't worry about that. It has no significance for you.

[0verd0ze]

From the DGIndex manual :rolleyes:

sooo that means that i should encode it at 23 fps with deinterlace, right? just wanna be sure .. .:)

[manono]

Hi-

Check the bottom of the D2V for the final FILM percentage. If it's really 99+%, then you can encode at 23.976fps, without deinterlacing.

[0verd0ze]

Hi-

Check the bottom of the D2V for the final FILM percentage. If it's really 99+%, then you can encode at 23.976fps, without deinterlacing.

FINISHED 99.55% FILM

[hdi20]

Just wanted to ask, how accurate DGIndex is in determining whether the source is interlaced or progressive.

[Guest]

Just wanted to ask, how accurate DGIndex is in determining whether the source is interlaced or progressive. DGIndex is very accurate at showing for each picture whether it is MPEG-encoded as progressive or interlaced, but that is not the same as telling you whether the content is interlaced or progressive. It is a common practice to encode progressive content as interlaced, and more seriously the converse. The preferred and most reliable way to discern video types is by separating the fields and inspecting them by eye.

[hdi20]

The preferred and most reliable way to discern video types is by separating the fields...How exactly do I do that?

[DigitAl56K]

Use AVISynth.

Something along the lines of:

LoadPlugin("DGDecode.dll")
MPEG2Source("Project.d2v")
AssumeTFF()
SeparateFields()

Switch out "AssumeTFF()" for "AssumeBFF()". Step through the content frame by frame in VirtualDub. You can tell when you have the wrong order because objects in motion will jump back and forth.

[manono]

Open the SeparateFields() script in VDub(Mod), scroll to a place with movement, and start advancing a frame at a time. Then if it was shot on video and is truly interlaced, each field will be different and unique. If it's film, it will display the telltale 2 3 2 3, where the numbers represent how many times the same field is viewed. That is, you'll get duplicated fields. That's 2:3 Pulldown for NTSC. PAL will have a 2 2 2 2 pattern if progressive.

[hdi20]

Thank you digital56k for script example, and thank you manono for pattern explanation. I'm curious about one more thing, in virtualdubmod I have saved image sequence and noticed a slight difference in vertical position between otherwise identical images.
example >>> http://www13.rapidupload.com/d.php?file=dl&filepath=3985
Why do this differences occur?

[DigitAl56K]

Remember that when the two fields are interlaced for display (equivelent to adding Weave() to the AVISynth script) they will be shown on alternate vertical lines, so there is a vertical offset for the bottom field.

I.e the top field starts on line 0, and is scanned out on even lines 2, 4, 6, 8 ... The bottom field starts on line 1 and is scanned out on odd lines 3, 5, 7, 9 ... This is why there is a difference.

P.S. If you look at a motion sequence you will probably find the fields are not identical, they are likely offset both temporally and spatially.