IVTC instead of ForceFilm

[KristenK]

I'm a little confused here. From all the guidelines and notes I read it seems to suggest you should always try to forcefilm first if possible, but if your source comes up as NTSC, film below 95%, or a d2v file with interlacing still, then you should create your d2v at 29.970 and check if you have the 3 frames solid / 2 frames interlaced pattern and only then use IVTC.

However, my question is that even films that show as as 99% Film or even just Film (100%), if you create the d2v file at 29.970 it seems I always get that pattern of 3 frames solid / 2 frames interlaced, which is perfect for IVTC.
I've tried encoding movies in the above case both IVTC and ForeFilm and they seem identical. So if you get the 3 frame /2 frame interlace pattern, (even though it shows up as Film) is there any reason not to use IVTC instead to be safe?

[Guest]

Suppose you have a 100% film stream (soft pulled down). That means it carries flags that instruct the display process to repeat fields so as to produce the 29.97 3-progressive/2-interlaced output. But the fields themselves are not actually duplicated in the stream. If you tell DGIndex to honor those flags, then MPEG2Source() will pulldown the fields to produce output with the actual fields duplicated. If you save the result, you then have a hard pulled-down stream.

If the stream is 100% film then Force Film will almost always be more reliable and faster than doing IVTC on the hard pulled-down stream. That's because Force Film just tells DGIndex to pretend that the flags are not present.

Doing IVTC on the hard pulled down stream is slower and not perfect because heuristics are used to match the fields.

Force Film can rarely fail even for 100% film, if the pulldown is applied to a source stream that is not clean progressive, such as field-blended garbage. Only manual inspection can tell you if you have one of these cases.

Also, be aware that IVTC on the hard pulled-down stream is not always "safe". For example, it will fail with field blends as well. If the IVTC has a post-processing phase, that can hide such pathologies, but you can achieve the same thing by using Force Film and applying postprocessing, such as with:

FieldDeinterlace(full=false)

[cody]

Hi, I am new to dvd backups, dgIndex etc so excuse any repeated questions.

I was reading the manual and got
If the clip is not PAL or MPEG1, and the Video Type field in the Information window indicates Film 95% or higher, it is likely that the clip can be treated as 3:2 pulldown material, and so the Force Film option should be selected for generation of the D2V file.

I have a NTSC interlaced source and I previewed the vob files but do not get the film %. Video Type field just says NTSC and frame rate's at 29.97. How do i find out the film %?
from log:
Stream Type: MPEG2 Program
Profile: main@main
Frame Size: 704x480
Aspect Ratio: 4:3
Frame Rate: 29.970030 fps
Video Type: NTSC
Frame Type: Interlaced
Coding Type: P
Colorimetry: BT.470-2 B,G
Frame Structure: Frame
Field Order: Top
Coded Number: 3414
Playback Number: 3414
Frame Repeats: 0
Field Repeats: 0
VOB ID: 2
Cell ID: 16
Bitrate: 4.258 Mbps
Bitrate (Avg): 4.398 Mbps
Bitrate (Max): 4.644 Mbps
Audio Stream: 80: AC3 3/2 384
Timestamp: 1:25:11
Elapsed: 0:01:53
Remain: FINISH
FPS: 29.94
Info:


Does that mean this source is not pulldown and I should use honour pull down flags? The reason I am confused is from testing dvdrebuilder which has the old version (06) has this in the d2v file for the same vobs.

DGIndexProjectFile06
..
Field_Operation=0 (0:None 1:ForcedFILM 2:RawFrames)
Frame_Rate=23976

edit: I believe I found the answer to my confusion, I have a pure interlaced source. The old version with rebuilder free must take the source is telecined and hence the problems and confusion.