telecide question - possible enhancement idea

wotef · 12th December 2002, 14:08

hi, have come across a problematic segment of a movie that was low-motion and very, very dark

the movie needs NTSC 3:2 pulldown; telecide and decimate do very well on normally lit and/or fast motion scenes, but trips up on the dark, slow scenes - matching sub-optimally between p/c/n

the problem gets compounded if it throws off pattern guidance later on, right?

- specifying manual telecide overrides solves the issue, but going through frame by frame by hand is unmanageable for long segments

- something i tried was to turn telecide's debug on, then to destaturate and tweak the contrast up real high with tweak(sat=0,cont=11), prior to telecide(guide=1,debug=true),decimate(cycle=5), then i logged the debug output with debugview and constructed an entire override file with the new telecide field-matching

p.s. tweaking brightness made no difference; contrast was the key

--> removed the tweak command and told telecide to use the new override file for the entire segment, and bingo, the results were MUCH better visually

following the same procedure on some bright scenes predictably seems to push the image into clipping, so the downside is that telecide will then fail again, this time cause it can't see lacing on whited-out frames

so i wonder what your thoughts would be on a possible enhancement for telecide --> in order to increase accuracy of field-matching on both (1) very dark, slow motion scenes & (2) very bright scenes that are already near clipping --> give telecide a way to measure average contrast on a frame by frame basis such that when below a certain floor, it will create a clip segment (where contrast is tweaked up and the field pattern is applied accordingly), and if the contrast is above a certain cap, it will create a clip segment (where contrast is tweaked down and the field pattern is applied accordingly)...all without touching the colour balance of the output clip, else...behave normally and integrate the disparate outputs into one progressive stream

not sure of the best way this would be implemented, perhaps switches/flags, threshold parameters...

but first of all, what do you think of the principle?

12th December 2002, 14:08	#1 \| Link
wotef Registered User Join Date: Apr 2002 Posts: 272	telecide question - possible enhancement idea hi, have come across a problematic segment of a movie that was low-motion and very, very dark the movie needs NTSC 3:2 pulldown; telecide and decimate do very well on normally lit and/or fast motion scenes, but trips up on the dark, slow scenes - matching sub-optimally between p/c/n the problem gets compounded if it throws off pattern guidance later on, right? - specifying manual telecide overrides solves the issue, but going through frame by frame by hand is unmanageable for long segments - something i tried was to turn telecide's debug on, then to destaturate and tweak the contrast up real high with tweak(sat=0,cont=11), prior to telecide(guide=1,debug=true),decimate(cycle=5), then i logged the debug output with debugview and constructed an entire override file with the new telecide field-matching p.s. tweaking brightness made no difference; contrast was the key --> removed the tweak command and told telecide to use the new override file for the entire segment, and bingo, the results were MUCH better visually following the same procedure on some bright scenes predictably seems to push the image into clipping, so the downside is that telecide will then fail again, this time cause it can't see lacing on whited-out frames so i wonder what your thoughts would be on a possible enhancement for telecide --> in order to increase accuracy of field-matching on both (1) very dark, slow motion scenes & (2) very bright scenes that are already near clipping --> give telecide a way to measure average contrast on a frame by frame basis such that when below a certain floor, it will create a clip segment (where contrast is tweaked up and the field pattern is applied accordingly), and if the contrast is above a certain cap, it will create a clip segment (where contrast is tweaked down and the field pattern is applied accordingly)...all without touching the colour balance of the output clip, else...behave normally and integrate the disparate outputs into one progressive stream not sure of the best way this would be implemented, perhaps switches/flags, threshold parameters... but first of all, what do you think of the principle?