MPEG2 interlaced DVD streams help

[xero9009]

I have several newbie questions. I'm ripping the mpeg streams from various DVDs using VOB2MPG Pro.

-When cutting, does it have to start on a key frame? What if I only select a chapter to output in VOB2MPG Pro and that particular chapter (indicated by the IFO) doesn't start on a key frame?
-These are all interlaced. Opening up some of these in avidemux, I can see the pattern for frames is I B B P B B P B B etc. Does this indicate a 2:3 pulldown? I notice though the video time doesn't start exactly at the zero mark, and Avidemux is being all finicky when trying to set the playback head to the few frames before it.
-Is there a way to deinterlace the mpeg files without quality loss? That would be ideal versus watching interlaced videos on a progressive display.
--If not, I'm assuming re-encoding can possibly still look better if I use something like QTGMC instead of playing the original interlaced mpeg stream using the software player deinterlacing filter (Yadiff 2x). Is this correct?

Thanks for any help on this!

[ndjamena]

1: Yes, you need to cut on a key-frame unless your program re-encodes the GOP which loses you quality.
2: Those are frames, not fields and have nothing to do with whether they are interlaced or not nor the type of interlacing used.
2.5: I haven't figured out AVIDemux time-codes myself. If I'm using a .ts file I know to always take the time-code from the previous frame rather than the one I actually want, as for MKV I can't be bothered even trying anymore.
3: There's no such thing as de-interlacing without losing quality, you already lost the quality when they interlaced it, and can only do your best to limit the damage.
4: Depends on how you re-encode it afterwards, but in general QTGMC does looks better than yadif.

[xero9009]

Thanks for the response. Is there a quick way to tell which type of interlacing is in a mpg stream? Based on your response I'd like to re-encode using QTGMC to deinterlace but I have no idea how to go about it, and exactly what is the right method for certain types of interlacing (whether I should inverse telecine or not for example).
I have pretty good settings for x264, but no idea if it's right for interlaced streams.

http://mattgadient.com/2013/06/12/a-best-settings-guide-for-handbrake-0-9-9/ <- is there somehow a way to use QTGMC with Handbrake, perhaps? I like the idea of it automatically detecting telecine or not. I'm trying to get the best quality possible, so if some deinterlace setting can have an otherwise avoidable averse effect on the quality (eg using the wrong setting for the 'type' of deinterlacing) I'd like to avoid it.

[ndjamena]

DGIndex can tell you if there's actual film or video elements in an MPEG2 stream, but quite a lot of pulldown is of the hard variety and there's no reliable way of detecting them short of looking at the video yourself and counting the frames. QTGMC is an AVISynth filter and if you're really interested in the highest quality AVISynth is the only way to go. AVISynth has a steep learning curve though, so it's only really an option if you're willing to put the time and effort in to master it.

You may not actually have to IVTC a DVD if it's already encoded as progressive with soft pulldown. Many TV Shows are recorded with both 24 fps and 60 fps elements which makes them difficult to deal with. The method of dealing with each individual DVD has to be considered on the DVDs own merits so there's no one size fits all solution.