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  #1  
08-08-2004, 08:11 PM
mabhz mabhz is offline
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Hi all,

i'm trying to put together a FILTERS FAQ (http://www.kvcd.net/forum/viewtopic.php?t=13078) on the portuguese forum from previous posts from all foruns, and still have some filters descriptions missing. So i thought this forum would be the best place to search for them!

I know all filters come with a readme file, and also there is http://www.avisynth.org/warpenterprises/ for more info, but what we are looking here is a more basic description geared towards beginer users, which find the readme and link info a bit complicated to understand.

A brief description of what the filter does and when one should use it (under what video sympton/condition) is more than enough.

Here's an example:
Blockbuster - used to remove the dreaded DCTBlocks, which are thouse ugly squares that apear all around your screen making you movie look like an irish kilt!

We need descriptions and usage conditions for the following filters:

Merge Chroma

Merge Luma

UnFilter

aSharp

Faery Dust

STMedianFilter

Convolution 3D

Undot

DctFilter

Limiter


Of course, when finished, the FAQ can/will be translated. If this could be considered a cross-posting, please moderators, lock or erase my post.


Thanks for any input!

PEACE!

mabhz
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  #2  
08-09-2004, 01:57 AM
Dialhot Dialhot is offline
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[quote="mabhz"]Hi all,

Hi.

I saw the post you did in the portuguese forum and I'm glad to see it in the english one. This way I will be abble to correct the mistakes you did

I don't have the time do comment all the filters (BTW you are just copying the doc for some of them like MergeLuma that is an internal filter of avisynth. All is in the doc, there is nothing to say more). I'll just correct 2 things I noticed in your other post.

DctFilter
IT IS NOT FOR FILTRERING DCT BLOCKS ! Despite the name
This filter is used to limit the bandwith of the DCT transform by cutting the high frequencies. That does not affect the visual aspect and increase a little the compression.

Deen
Is a spatio-temporal filter, and not a spatial only one.
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  #3  
08-09-2004, 03:00 PM
mabhz mabhz is offline
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Hi there, Dialhot. Thanks a lot for taking the time and helping me out!

Well, actually i'm not copying the avaliable documentation. All the filter comments i included on that thread i took from two previous posts by Luciano Cabrera anb Muadib. I did an extensive (believe me, i must have read over 50 posts looking for info on filters!) and those two where the only ones i found that had that sort of information.

As i said on the portuguese forum, i dont agree that all the needed info is on the documentation, neither the readmes that come with each filter nor the avisynth site. At least not for a beginner like me!! And i believe many more stay cluelles after reading stuff like this:

. Convolution3D is an avisynth filter that will apply a 3D convolution to all pixel of a frame. - what the heck is a 3d convolution anyway?

. DctFilter (...) will do a Discrete Cosine Transform (DCT), (...) and then reverse the process with an Inverse Discrete Cosine Transform (IDCT). - what in Gods earth is a discrete cosine transform? is it a french dish??

and sentences like "don't spatial filter pixel if it would change it more than this" and "It fairly very fine grained, using only adjacent pixels" makes no sense to my fairly good english (both taken from STMedianFIlter docs).

So the idea is to translate much of the techniqual blah-blah-blah, like "limit the bandwith of the DCT transform by cutting the high frequencies" (from your post) and make it understandable to dumb beginners like me. I'm trying to do that because now that, after over an year of struggle, i can finaly produce working kvcds, i noticed that filters play a great part on the final quality/size of the video.

Thats why the "format" i'm trying to stick to on the descriptios is "what the filter does" and "when to use", both on very very easy/lame/for dummies language.

If you dont mind, i'd like to post two questions... if you (or someone else) manage to find some time to explain them, i'd more than grateful!

1- What is a temporal and a spatial filter? i assume a "spatial" one tries to reduce the final size of the mpeg on the HD, is that right? but i have no clue concerning the "temporal" one.

2- If i have a very good source, a DVD vob file, for instance, i MUST use filters on my script anyway or i will just use them to fix problems or increase difinition or compress the final file size?? I ask this because most beginners use MovieStacker which generates a basic script with default filtes activated, like mergechroma, mergeluma, undot, stmedianfilter, etc. And i wonder if i really need them all the time for all my kvcds.

thanks!!!

PEACE to us all.....

mabhz

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  #4  
08-10-2004, 02:41 AM
Dialhot Dialhot is offline
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Quote:
Originally Posted by mabhz
Well, actually i'm not copying the avaliable documentation.
My sentence was badly turned : I wanted to ay that for MergeLuma for instance, there is nothing to add to what is already in the doc. Your faq should start by a big : RTFM
How many people had read the wonderful doc that is delivered with avisynth ? (How many even know that there IS a manual delived with avisynth ? )

Note one thing also : MergeChroma DOESN'T DO ANYTHING ALONE !
We always use it with "MergeChroma(Blur(...))" and that is this combination that is usefull
MergeChroma alone or used with other thing than blur doesn't have a lot of interest for our purpose.
will you indicate this in your faq ?


And I was talking about SOME FILTERS ! Not all and everyone so calm you nerves down !

Quote:
- what the heck is a 3d convolution anyway?
It's a basical matrix opereration ! That's maths. You want to explain all the words ?
What is a pixel ? What is the Luma ? What means Chroma ? What stands behind the letters 'D' 'C' 'T'... ? You see where this can lead ?

It's probable that you already know all these words but you didn't know C3D so you can imagine that a lot of people don't know DCT for instance.

Quote:
- what in Gods earth is a discrete cosine transform? is it a french dish??
Okay, that's become touchy . You used "reduce DCT blocks" and never noticed than DCT means "Discrete Cosine Transform" ? So you try to explain something with words you don't understand ?

Quote:
So the idea is to translate much of the techniqual blah-blah-blah, like "limit the bandwith of the DCT transform by cutting the high frequencies" (from your post) and make it understandable to dumb beginners like me.
Okay, good idead but telling "reduce DCT blocks like its name says it !" it's completly wrong and that is what I wanted to correct. If I do'nt give you any reason for why you are wrong, will you just trust me and don't try to understand ? I won't do in your situation.

DCTFilter DOES NOT REDUCE DCT BLOCKS AT ALL ! It just increase the compressibility (by cutting blah blah blah... but you can remove this part from your FAQ if you want)

Quote:
I'm trying to do that because now that, after over an year of struggle, i can finaly produce working kvcds, i noticed that filters play a great part on the final quality/size of the video.
For sure ! But if you have a DCT block problem and try to bypass it by using DCTFilters, you will have a lot of bad time

Quote:
Thats why the "format" i'm trying to stick to on the descriptios is "what the filter does" and "when to use", both on very very easy/lame/for dummies language.
I understood you well. But just one thing : you explain in few words what and when use C3D, okay. But... C3D has 7 parameters... what dummies will do with them ?
They will just... post a message to ask ! So the problem will just go a step further

Quote:
1- What is a temporal and a spatial filter? i assume a "spatial" one tries to reduce the final size of the mpeg on the HD, is that right? but i have no clue concerning the "temporal" one.
All this in in the avisynth doc (perhaps the one that is online... not sure). BTW, a spatial filter reduce noise that is within a frame (a pixel is compared to its neighbours in the same frame), a temporal noise compare a pixel and its value in the next (sometimes also previous) frame to decide if it has to be kept or removed.

And ALL denoiser filters try to reduce "noise" that lead to reduce the size of the file on the HD.


Quote:
2- If i have a very good source, a DVD vob file, for instance, i MUST use filters on my script anyway or i will just use them to fix problems or increase difinition or compress the final file size??
In the theorical case of a "noise clean" source (that does not exists really, even the best DVD vobs needs little noise filtering), you can drop all denoiser (denoiser = spatial/temporal/spatio-temporal filters).
But you have other filters than denoiser : DCTFilter, Limiter, Blockbuster...

These filters have the common goal to reduce the file size of the ended movie without affecting the visual aspect of the picture. And they reach this goal by different means...

Quote:
I ask this because most beginners use MovieStacker which generates a basic script with default filtes activated, like mergechroma, mergeluma, undot, stmedianfilter, etc. And i wonder if i really need them all the time for all my kvcds.
Look at our optimal "script for clean DVD sources" and you will see that yes, you need them all !

Note: I noticed that you didn't correct the FAQ in the portuguese forum. Soç I assume that I can just stop to add my words to this thread...
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  #5  
08-10-2004, 03:14 AM
incredible incredible is offline
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Send a message via ICQ to incredible
In other words, ....

www.google.com

.... is your best friend!

Youll find hunderts of useful Informations about DCT, YUV Formats etc.

Go into your avisynth25 folder and you find the "Docs" Directory where in the english section is everything well explained.

The merge command for instance is regulary like a layover with opacity option.
http://www.avisynth.org/Merge

just enter the needed filtername into avisnyth.org's search engine upper left side and you will find all internal filters. In case of external filters do just look into the filter-delivered readme docs.
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