With an 8mm source (captured with AIW9600XT) I ran it through Hybrid. Under the tabs Filtering -- (De-)Interlace/Telecine I checked the Bob box.. Guide on right side says: If enabled QTGMC will create one frame per field of the source and thus double the frame rate and count. If disabled (default) QTGMC will still create one frame per field of the source, but only output half of the frames and this keep the frame rate and count identical to the source.
When I turn on Bob (ha!) the effect is jerky motion. Going frame by frame, I can see why. It's like for every step forward in frame 1, there is a half-step back in frame 2. I guess this makes sense.
My question: in what kind of source video would one turn on Bob?
The problem you describe is incorrect assumed field order.
Avisynth by default assumes Bottom Field First for AVI input. I don't know how to do it in Hybrid off the top of my head, but the Avisynth command you need is AssumeTFF (placed before any deinterlace filter). I'm sure QTGMC also has an option to manually force either field order.
in what kind of source video would one turn on Bob?
All of them.
I am not familiar with Hybrid because I prefer to manually choose all my settings rather than relying on a GUI, but when you deinterlace you want to double the framerate in QTGMC, otherwise you loos ehalf of the motion. http://www.digitalfaq.com/forum/vide...mc-script.html
A channel on S-VHS / VHS capture and AviSynth restoration https://bit.ly/3mHWbkN
This is not true. It loses some motion, yes, but not half. Remember that QTGMC is interpolating. With some content, arguably you lose nothing. With others, noticeable motion loss (but not anywhere near as often as some seem to think).
In fact, you can create artifacts with 59.94 (50 PAL), which require more Avisynth workarounds, some of it quite complex and lengthy to encode.
So never just double the framerate, and expect it to be fine. Odds are it's not fine. Remember, deinterlace is destructive, and in every way imaginable.
So never just double the framerate, and expect it to be fine. Odds are it's not fine. Remember, deinterlace is destructive, and in every way imaginable.
My bad, but I did not understand a word. Can you give some example?
A channel on S-VHS / VHS capture and AviSynth restoration https://bit.ly/3mHWbkN
interlaced frames video, 25 frames (50 fields) per second (25 frames i)
frame1 frame2 frame3 frame4 frame5 frame6 frame7 frame8
A C E G (field 0) even lines
b d f h (field 1) odd lines
PAL50Ii --> field 0 and field 1 are even and odd lines of "camera" frames taken at different time
each field contains different temporal data
When you deinterlace:
Code:
frame1 frame2 frame3 frame4 frame5 frame6 frame7 frame8
A B' C D' E F' G H' (field 0) even lines
a' b c' d e' f g' h (field 0) odd lines
x' and X' represents scanlines interpolated from X and x
If you set QTGMC to discharge a frame:
Code:
frame1 frame2 frame3 frame4
A C E G (field 0) even lines
a' c' e' g' (field 0) odd lines
you do loose half of the motion. If there is no motion between the different frames, you do not loose anything, but that's a special case
