Use decross before or after ivtc (source)?

HOLiC · 14th February 2006, 11:28

I have been trying to find out more information about this filter, but there is almost no information out there!! However, i did managed to find the japanease site with this filter (not that i understand japanease). And it seems like it's used for getting rid of rainbows and something about "cross colors".. is this correct?

anyway, what I want to know is if it is okey to use this filter before you ivtc your source, like this:

mpeg2source()
decross()

or is this wrong? thank you~

Mug Funky · 14th February 2006, 12:50

run it before IVTC. IVTC will mung the field order, which is good if you want progressive frames, but bad if you're using the actual order of fields to cancel stuff out. dedot is this way - it must be run before anything else as it needs the exact fields that were captured.

also, if decross is successful it'll reduce false matches in your IVTC, giving a better result there as well.

Didée · 14th February 2006, 13:54

A link to decross, for the busy people?

Chainmax · 14th February 2006, 16:05

Hey, it's on the same website as DeDot!

It's probably made by theJam too then, right?

niiyan · 14th February 2006, 17:11

@Chainmax:

Quote:

Originally Posted by Chainmax

It's probably made by theJam too then, right?

It was made by minamina, referring to the crosscolor plugin for AviUtl (crosscolor.auf).

@all:

Here is a part of Japanese-English translation of DeCross.txt.

Code:

- Usage

 LoadPlugin("DeCross.dll")
 DeCross(clip, ThresholdY, Noise, Margin, Debug)

 ThresholdY : Threshold for edge detection (0 to 255, default 30)
 Noise      : Considered as noise if more or equal than this value. (0 to 255, default 60)
 Margin     : The edge detection part is expanded right and left. (0 to 4, default 1)
 Debug      : Show the area the filter applied (default false)

Chainmax · 15th February 2006, 13:55

I see, thanks. Could you please post the complete translation?

niiyan · 15th February 2006, 16:08

Here:

Code:

DeCross.dll v0.0.02 Copyright(C) 2003, 2004 minamina

Avisynth Plugin - Cross Color Reduction (YUY2 and YV12 Only)


- Explanation

 Cross Color reduction plugin for Avisynth.
 It supports YUY2 and YV12.
 Avisynth 2.5 only.
 MMX required.

 It was made by referring to the crosscolor filter for AviUtl in Shou's Page.
 Thanks Shou.


- Usage

 LoadPlugin("DeCross.dll")
 DeCross(clip, ThresholdY, Noise, Margin, Debug)

 ThresholdY : Threshold for edge detection (0 to 255, default 30)
 Noise      : Considered as noise if more or equal than this value. (0 to 255, default 60)
 Margin     : The edge detection part is expanded right and left. (0 to 4, default 1)
 Debug      : Show the area the filter applied (default false)


- Example

 DeCross()
 DeCross(28, 80, 2, false)
 DeCross(ThresholdY = 40, Margin = 1)


- History

 2004/02/01 v0.0.02 Fixed the problem that it couldn't be read by using LoadPluginEx + AviSynth 2.0.x.
 2003/12/26 v0.0.01 Initial Release.

Chainmax · 15th February 2006, 16:23

Thanks

. It doesn't say wether it can be applied before IVTCing/Deinterlacing though.

foxyshadis · 15th February 2006, 21:39

It might be the same as bifrost, ie, use it depending on whether it was introduced before or after telecining. I don't know if it's similar enough though.

niiyan · 16th February 2006, 17:08

The documentation of the AviUtl's crosscolor plugin says:

Code:

- Directions -

If you don't use it before deinterlacing, this filter has no effect.
It doesn't work, except when the width of the image is 640,
704 or 720.

I don't know whether that is true of DeCross.

Wilbert · 16th February 2006, 21:13

You always need to apply such filters before any deinterlacing, because it uses the periodicity of the signal to get rid of the noise. Deinterlacing destroys that periodicity.

Chainmax · 16th February 2006, 22:03

But do all these kind of filters support interlaced processing?

Mug Funky · 18th February 2006, 15:17

it really depends on what assumptions are made about the artefacts.

a generic "spatial chroma nuke" de-rainbower would work equally on interlaced or progressive material, because it'd use only basic and brutal means of detection and elimination. some actually need an interlaced picture to work, though.

after all, rainbows/dot-crawls only occur with composite video, which is _always_ interlaced regardless of whether the actual signal contains an interlaced or progressive (or telecined) picture. so the crosstalk that comes from it will be per-field, and thankfully first and second fields cancel out (which is why it's actually quite hard to see rainbows on a TV fed with composite - your eyes work slower than the field rate, so it largely cancels out before it hits your brain).

14th February 2006, 11:28	#1 \| Link
HOLiC Registered User Join Date: Jan 2006 Posts: 32	Use decross before or after ivtc (source)? I have been trying to find out more information about this filter, but there is almost no information out there!! However, i did managed to find the japanease site with this filter (not that i understand japanease). And it seems like it's used for getting rid of rainbows and something about "cross colors".. is this correct? anyway, what I want to know is if it is okey to use this filter before you ivtc your source, like this: mpeg2source() decross() or is this wrong? thank you~

14th February 2006, 12:50	#2 \| Link
Mug Funky interlace this! Join Date: Jun 2003 Location: i'm in ur transfers, addin noise Posts: 4,555	run it before IVTC. IVTC will mung the field order, which is good if you want progressive frames, but bad if you're using the actual order of fields to cancel stuff out. dedot is this way - it must be run before anything else as it needs the exact fields that were captured. also, if decross is successful it'll reduce false matches in your IVTC, giving a better result there as well. __________________ sucking the life out of your videos since 2004

14th February 2006, 13:54	#3 \| Link
Didée Registered User Join Date: Apr 2002 Location: Germany Posts: 5,391	A link to decross, for the busy people? __________________ - We´re at the beginning of the end of mankind´s childhood - My little flickr gallery. (Yes indeed, I do have hobbies other than digital video!)

14th February 2006, 16:05	#4 \| Link
Chainmax Huh? Join Date: Sep 2003 Location: Uruguay Posts: 3,103	Hey, it's on the same website as DeDot! It's probably made by theJam too then, right? __________________ Read Decomb's readmes and tutorials, the IVTC tutorial and the capture guide in order to learn about combing and how to deal with it.

15th February 2006, 13:55	#6 \| Link
Chainmax Huh? Join Date: Sep 2003 Location: Uruguay Posts: 3,103	I see, thanks. Could you please post the complete translation? __________________ Read Decomb's readmes and tutorials, the IVTC tutorial and the capture guide in order to learn about combing and how to deal with it. Last edited by Chainmax; 15th February 2006 at 14:03.

15th February 2006, 16:23	#8 \| Link
Chainmax Huh? Join Date: Sep 2003 Location: Uruguay Posts: 3,103	Thanks . It doesn't say wether it can be applied before IVTCing/Deinterlacing though. __________________ Read Decomb's readmes and tutorials, the IVTC tutorial and the capture guide in order to learn about combing and how to deal with it. Last edited by Chainmax; 15th February 2006 at 16:27.

15th February 2006, 21:39	#9 \| Link
foxyshadis Angel of Night Join Date: Nov 2004 Location: Tangled in the silks Posts: 9,559	It might be the same as bifrost, ie, use it depending on whether it was introduced before or after telecining. I don't know if it's similar enough though.

16th February 2006, 17:08	#10 \| Link
niiyan Registered User Join Date: Sep 2002 Posts: 88	The documentation of the AviUtl's crosscolor plugin says: Code: - Directions - If you don't use it before deinterlacing, this filter has no effect. It doesn't work, except when the width of the image is 640, 704 or 720. I don't know whether that is true of DeCross.

16th February 2006, 21:13	#11 \| Link
Wilbert Moderator Join Date: Nov 2001 Location: Netherlands Posts: 6,364	You always need to apply such filters before any deinterlacing, because it uses the periodicity of the signal to get rid of the noise. Deinterlacing destroys that periodicity.

16th February 2006, 22:03	#12 \| Link
Chainmax Huh? Join Date: Sep 2003 Location: Uruguay Posts: 3,103	But do all these kind of filters support interlaced processing? __________________ Read Decomb's readmes and tutorials, the IVTC tutorial and the capture guide in order to learn about combing and how to deal with it.

18th February 2006, 15:17	#13 \| Link
Mug Funky interlace this! Join Date: Jun 2003 Location: i'm in ur transfers, addin noise Posts: 4,555	it really depends on what assumptions are made about the artefacts. a generic "spatial chroma nuke" de-rainbower would work equally on interlaced or progressive material, because it'd use only basic and brutal means of detection and elimination. some actually need an interlaced picture to work, though. after all, rainbows/dot-crawls only occur with composite video, which is _always_ interlaced regardless of whether the actual signal contains an interlaced or progressive (or telecined) picture. so the crosstalk that comes from it will be per-field, and thankfully first and second fields cancel out (which is why it's actually quite hard to see rainbows on a TV fed with composite - your eyes work slower than the field rate, so it largely cancels out before it hits your brain). __________________ sucking the life out of your videos since 2004