where to apply deinterlacing and ivtc ?

[codemaster]

In case of MPEG2 streams from PAL and NTSC DVD's, there is something that I don't understand about deinterlacing and ivtc, and that is: when should they be applied.

Interlaced sources should be deinterlaced completely, from first frame to last frame ? Or just some portions or some ranges of frames need to be deinterlaced ?

How do I find out when and where to apply ivtc ? If there are only one or two scenes that need ivtc, and the rest of the content doesn't need ivtc, how do I detect only the scenes or range of frames that need ivtc ?

[poisondeathray]

In case of MPEG2 streams from PAL and NTSC DVD's, there is something that I don't understand about deinterlacing and ivtc, and that is: when should they be applied.

Interlaced sources should be deinterlaced completely, from first frame to last frame ? Or just some portions or some ranges of frames need to be deinterlaced ?

How do I find out when and where to apply ivtc ? If there are only one or two scenes that need ivtc, and the rest of the content doesn't need ivtc, how do I detect only the scenes or range of frames that need ivtc ?

IVTC never applies to PAL DVD's ; it's only applicable to NTSC DVD's

IVTC is the process of reversing telecine, to get the original progressive frames back . 24p content is "stored" as interlaced 29.97 frames/s or 59.94 fields/s on NTSC DVD's to be compatible with NTSC equipment. This only appiles to 24p content (e.g. theatrical films), not interlaced content

You need to examine the fields to determine if/when to apply IVTC. If it's a mix or hybrid case, then you can make VFR , or encode as interlace, or just deinterlace it. There are pros/cons to each method depending on what your destination goals are

[manono]

How do I find out when and where to apply ivtc ? If there are only one or two scenes that need ivtc, and the rest of the content doesn't need ivtc, how do I detect only the scenes or range of frames that need ivtc ?

Assuming it's not a hybrid, and some of it is hard telecined (needs IVTC) and some soft telecine (doesn't need IVTC), then you don't have to find it yourself, but the TIVTC IVTC can read the D2V you make in DGIndex and IVTC that which needs it and leave the rest alone (except for an interlacing check if using the default setting). From The TFM doc from TIVTC:

D.) FILE INPUT/OUTPUT PARAMETERS:


These settings deal with overrides file usage and output/input file options.


d2v -

This option is intended to be used if you are using an mpeg2source() with a d2v file.
It sets the name and path to a d2v file, which TFM will analyze to see if there are any
illegal field order changes and optionally set the order parameter using the field
order of the d2v file. If the d2v file is found to have illegal field order transitions,
TFM will create a fixed d2v file with the string "-FIXED" attached to the end of the file
name. The new file will be located in the same directory as the original. You can then
use this fixed d2v file for processing. If the order parameter is set to "-1" then TFM
will detect the field order from the d2v file and set the order parameter to match. Depending
on the value of the "flags" parameter, TFM will also use the d2v info for field matching
and will pass info from the d2v on to tdecimate to help aid duplicate detection and hybrid
detection.

*NOTE: This option currently supports all d2v formats that I am aware of... which
include: dvd2avi 1.76, 1.77.3 and its variants, all dvd2avidg versions, and
all dgindex versions.

example => TFM(d2v="myd2v.d2v")

Default: "" (String)


flags -

Controls how much of the info from the d2v file is used when the "d2v" parameter is set.
Possible options:

0 - Check the d2v file for illegal transitions and set the order parameter if it
is not already manually set. Also, pass on rff flag duplicate info to
tdecimate.
1 - Same as 0, plus use the trf flags for field matching in film sections (sections
where the trf flags follow the 012301... pattern)
2 - Same as 1, but use the trf flags for field matching in all areas (doesn't have
to be in 0123 pattern) (very much not recommended!)
3 - Same as 0, but don't pass on any info to tdecimate (i.e. only set order and check
for illegal transitions)
4 - Same as 1, but d2v matches are checked for being combed. If a d2v match is detected
as combed then tfm uses its own matching routine for that frame.
5 - Same as 4, but d2v matches are only checked for being combed around scenechanges.

VERY IMPORTANT (MUST READ): For options 0, 1, 2, 4, and 5 to work correctly, tfm/tdecimate
must either immediately follow the mpeg2source() command or
any filters inbetween them must not modify the order or number
of fields in the stream in any way. Or use a trimIn file to
tell TFM what frames have been discarded.

Default: 4 (int)

The first boldfaced line above shows how you'd use it in an AviSynth script. The second boldfaced section explains how it uses the information in the D2V to do the field matching when it's soft telecine. You can open the D2V in Notepad and have a look yourself.