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[HELP] Convert 29.97 to 23.976
#1
What's the best way of de-interlacing 29.97 video using QTGMC to 23.976 and keeping the same running time?
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#2
Set Input scan to: telecine or telecine(soft) (I still can't understand what is the difference between these two for Hybrid)
Deinterlace handling: TIVTC
deinterlacer in TIVTC settings: QTGMC (check GPU support)
This will output 23.976 fps.
There are some tests and explanations about some different situations and problems with telecine in this thread https://forum.selur.net/thread-1942-post...l#pid12847

Sometime NTSC 29.97 source also recorded as simply interlaced (same as PAL usually) so in this scenario you need to deinterlace it to 29.97 or to 59.94 with QTGMC bob and then somehow downconvert to 23.976 fps.
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#3
  • if your source is NTSC intelaced, going to 23.976 fps is really not recommended since you would throw away motion data and might end up with jerky motions.
  • if your source is NTSC telecine (no matter if it's soft telecine or not, since Hybrid tries to handle them the same way: decode as 29.97 and ivtd), you should use an IVTC filter, yes using QTGMC for deinterlacing as part of IVTC might help to preserve some more quality.
  • if your source is NTSC with a non-standard but constant telecine pattern you can use a IVTC method and adjust the settings to match the pattern.
  • if your source is an NTSC source with a non-standard non-constant telecine pattern, using QTGMC in Bob-mode and using sRestore to get rid of the duplicates is recommended.
  • if your souce is NTSC and hybrid (= wild mix of everything) you could bob the content with QTGMC and use sRestore to remove duplicates and ghosting.
  • if your source is PAL and non-standard interlaced your best chance, aside from doing some serious analysis of the source - and adjust filtering manually, is to QTGMC Bob and using sRestore in case you want/need to remove duplicates. Depending on the content you could also use QTGMC bob deinterle, use sRestore to a frame rate where you get rid of all duplicates and then use an interpolation method (Interframe/SVP, Rife, FrameRateConverter,..) to get to a specific higher frame rate, but depending on the interpolation method you might need another sRestore round after the interpolation.

Quote:Sometime NTSC 29.97 source also recorded as simply interlaced (same as PAL usually),...
'usally' *gig* that totally depends on the content you handle. Personally I as got as never have to deal with NTSC content that isn't telecined or PAL content that isn't progressive. If I get interlaced PAL content it's usually 10+years old or from a DVD. The real horror starts if you get content that was converted multiple times between NTSC and PAL and may be even consits of a wild mix of interlaced, field shifted, telecined content and some parts that use some really uncommon handling.

-> If your content doesn't fit in the normal categories: learn to properly analyse such content and write Vapoursynth/Avisynth scripts on your own.

Quote:What's the best way of de-interlacing 29.97 video using QTGMC to 23.976 and keeping the same running time?
QTGMC doesn't do 29.97 -> 23.976 pulldown, that is either IVTC oder some other pulldown.

Cu Selur
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#4
It's a shot on video movie (NTSC, SD). I need to edit clips into a 23.976 1080p timeline.
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#5
Quote:video movie (NTSC, SD).
Since I'm unsure on how to interprete that, try the following:
  • load the source in Hybrid
  • Overwrite the scan type to progressive in case the content wasn't detected as progressive which I assume.
  • check the Vapoursynth preview (and look at a scene with horizontal movement): Do you see combing artifacts?
    No -> your content is progressive and you should use sRestore to get to the frame rate you want to go. Finished.
    Yes-> your content isn't progressive. Smile
  • Overwrite the scan type to either tff or bff in case it was detected as telecine or progressive
    Hybrid now should select QTGMC as deinterlacer
  • enabled the Bob-option in QTGMC
  • check the Vapoursynth preview (and look at a scene with horizontal movement): Do your see motion from one frame to the next for each frame?
    Yes, each frame differs from the next -> your content is interlaced. Make sure the scan type is either tff or bff, use QTGMC in Bob mode and use sRestore to get to 23.976. Finished.
    No, there are three frames which differ and a forth that is repeated once -> your content is telecine, make sure the scan type is 'telecine' and use an IVTC method. Finished.
  • No, there is a fixed pattern to repeated frames but it isn't 3:2 -> you require a non-common pulldown. Make sure the scan type is set to 'telecine' and adjust the settings to handle your content. If you end up with a frame rate above 23.976 use sRestore to archive it. If you end up with a frame rate above 23.976 fps use an interpolation method to archive 23.976 (depending on the chosen method an additional sRestore call might be needed). Finished.
  • No, there are repeated frame but there is no pattern to it. -> argh, your content is shit. Set the scan type to either tff or bff, use QTGMC Bob and then sRestore to archive 23.976.
Once could also use some blend deinterlacing + decimation, to go from 29.97fps interlaced to 23.976 fps, but that is something Hybrid does not and will not support, since I thing that blend deinterlacing is and always was a bad idea.

Cu Selur

Ps.: for general handling of content questions, better go to a forum like videohelp.com or similar so that you can get the opinion of other folks on how to handle content. Especially if you are not hell bend to use Hybrid.
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#6
I now have another 29.97 file which mixes interview footage shot at 29.97 and film footage. The film footage has simply been dropped into the 29.97 edit and that has resulted in the film footage having dupe frames.

I have tried "bobbing" the video, but some scenes have a white box outline and the bobbing can be seen quite clearly after running through sRestore to 23.976, with the white line bobbing up and down. Very distracting. The video footage also has a burned in 29.97 timecode. If I leave at 29.97 the film footage has duped frames, if I sRestore to 23.98 to fix the film footage, then the video footage will not be correct. Any suggestions?
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#7
afk. atm. if you can share a short sample I can look at it in a few hours when I am back home.
You could keep everything at 29.97fps and replace the duplicates with interpolated frames (Filtering->Vapoursynth->Frame->Misc->FillDrops) for interview footage where there isn't much movement, this should produce good results. (Important: adjust the threshold to your source; use the 'Debug'-suboption to find a good value)

Cu Selur
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