Bill Nye - Top fields are sharp but bottom fields are blurry. Why?

Katie Boundary · 1st May 2024, 05:23

Obviously, the way to deal with it is with a purely spatial bobber like NNEDI3 in single-rate mode, but I'm interested in what could possibly cause such a bizarre phenomenon. Bad telecine hardware?

wonkey_monkey · 1st May 2024, 17:36

You've been here long enough to know that no-one's going to be able to even attempt to answer that without a sample, or at the very least the provenance of your source. Being more specific than "Bill Nye" might also be useful.

Katie Boundary · 23rd February 2025, 23:26

Found a really spectacular example today basically by accident...

https://www.mediafire.com/file/p94bc...muxed.m2v/file

hello_hello · 24th February 2025, 11:18

I'm guessing, but if you try to bob de-interlace (it's progressive isn't it?), the lines in one field might be in a better position to be interpolated into a full frame than the other, and therefore it looks sharper. Plus there's a lot of noise, which is probably the main culprit, and with the movement it sometimes results in one field looking more blurry, but not always the same one, so I'm not sure one field is inherently blurred, at least not in this case. If you bob de-interlace with something like Yadif, you'll definitely end up with some sharp and blurry frames, but it's not always the same interpolated field that looks blurry. QTGMC handles it pretty well.

Stacked fields

https://i.ibb.co/tTTHkznp/A.png

Yadif(mode=1).Subtitle("Yadif")
Frame()
A = last
B = A.Trim(1,0)
StackHorizontal(A, B)

https://i.ibb.co/7txk0qLB/B.png

QTGMC().Subtitle("QTGMC")
Frame()
A = last
B = A.Trim(1,0)
StackHorizontal(A, B)

https://i.ibb.co/FqhRrqqd/C.png

Z2697 · 25th February 2025, 08:45

My guess is the video is fake interlacing but low quality deinterlaced from an interlaced source

Katie Boundary · 13th March 2025, 03:58

Quote:

Originally Posted by Z2697

My guess is the video is fake interlacing but low quality deinterlaced from an interlaced source

Not likely. Other parts of the episodes are true 60 fps.

huhn · 13th March 2025, 07:03

that does not dismiss his guess what so ever.

Katie Boundary · 16th March 2025, 21:40

Quote:

Originally Posted by huhn

that does not dismiss his guess what so ever.

If bob-deinterlacing had been performed at any step on the journey to DVD, I'd expect it to be after the episodes were edited together but before they were put on DVD. As in, the DVDs wouldn't be broadcast accurate. I'm not even sure that bob-deinterlacing existed in 1993 or that it could be done with analog equipment.

wonkey_monkey · 17th March 2025, 11:34

Quote:

I'm not even sure that bob-deinterlacing existed in 1993 or that it could be done with analog equipment.

It did, and it could, and it was.

huhn · 17th March 2025, 11:40

a bob deint is just a specialist scaling operation. so they could do such an operation at anytime they wanted in digital processing. they could take square film scans and make them anamorphic i'm sure they can also bilinear bob at that time...

the dvd is from 1996 so what ever they did in 1993 does not matter what matters is what they used as a source and them it was dumbed on a DVD like that.

the file is interlaced 30 that is not truly PSF while been PsF now. the number of soft trash fields is also relative low. the file is also full with weave artifacts while been not interlaced "anymore".

a messes up deint and it been fake interlaced is a very very good guess. if there are parts that are true interlaced or parts that are not trash doesn't matter we have this sample nothing else and this is that fake interlaced/PsF from a weaved bad interlaced source where if deint some fields are low res.

1st May 2024, 05:23	#1 \| Link
Katie Boundary Registered User Join Date: Jan 2015 Posts: 1,099	Bill Nye - Top fields are sharp but bottom fields are blurry. Why? Obviously, the way to deal with it is with a purely spatial bobber like NNEDI3 in single-rate mode, but I'm interested in what could possibly cause such a bizarre phenomenon. Bad telecine hardware? __________________ I ask unusual questions but always give proper thanks to those who give correct and useful answers.

1st May 2024, 17:36	#2 \| Link
wonkey_monkey Formerly davidh***** Join Date: Jan 2004 Posts: 2,641	You've been here long enough to know that no-one's going to be able to even attempt to answer that without a sample, or at the very least the provenance of your source. Being more specific than "Bill Nye" might also be useful. __________________ My AviSynth filters / I'm the Doctor

23rd February 2025, 23:26	#3 \| Link
Katie Boundary Registered User Join Date: Jan 2015 Posts: 1,099	Found a really spectacular example today basically by accident... https://www.mediafire.com/file/p94bc...muxed.m2v/file __________________ I ask unusual questions but always give proper thanks to those who give correct and useful answers.

24th February 2025, 11:18	#4 \| Link
hello_hello Registered User Join Date: Mar 2011 Posts: 4,999	I'm guessing, but if you try to bob de-interlace (it's progressive isn't it?), the lines in one field might be in a better position to be interpolated into a full frame than the other, and therefore it looks sharper. Plus there's a lot of noise, which is probably the main culprit, and with the movement it sometimes results in one field looking more blurry, but not always the same one, so I'm not sure one field is inherently blurred, at least not in this case. If you bob de-interlace with something like Yadif, you'll definitely end up with some sharp and blurry frames, but it's not always the same interpolated field that looks blurry. QTGMC handles it pretty well. Stacked fields https://i.ibb.co/tTTHkznp/A.png Yadif(mode=1).Subtitle("Yadif") Frame() A = last B = A.Trim(1,0) StackHorizontal(A, B) https://i.ibb.co/7txk0qLB/B.png QTGMC().Subtitle("QTGMC") Frame() A = last B = A.Trim(1,0) StackHorizontal(A, B) https://i.ibb.co/FqhRrqqd/C.png Last edited by hello_hello; 24th February 2025 at 22:17.

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25th February 2025, 08:45	#5 \| Link
Z2697 Registered User Join Date: Aug 2024 Posts: 457	My guess is the video is fake interlacing but low quality deinterlaced from an interlaced source

13th March 2025, 07:03	#7 \| Link
huhn Registered User Join Date: Oct 2012 Posts: 8,339	that does not dismiss his guess what so ever.

17th March 2025, 11:40	#10 \| Link
huhn Registered User Join Date: Oct 2012 Posts: 8,339	a bob deint is just a specialist scaling operation. so they could do such an operation at anytime they wanted in digital processing. they could take square film scans and make them anamorphic i'm sure they can also bilinear bob at that time... the dvd is from 1996 so what ever they did in 1993 does not matter what matters is what they used as a source and them it was dumbed on a DVD like that. the file is interlaced 30 that is not truly PSF while been PsF now. the number of soft trash fields is also relative low. the file is also full with weave artifacts while been not interlaced "anymore". a messes up deint and it been fake interlaced is a very very good guess. if there are parts that are true interlaced or parts that are not trash doesn't matter we have this sample nothing else and this is that fake interlaced/PsF from a weaved bad interlaced source where if deint some fields are low res.