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-   -   Avisynth: ColorMatrix (http://www.digitalfaq.com/archives/avisynth/13365-avisynth-colormatrix.html)

Dialhot 03-01-2005 06:19 AM

ColorMatrix
 
Hi,

I saw the word "colormatrix" sometimes in some posts (Inc, Boulder...) but nobody never focused on it.
I just found a thread in the Portuguese forum where someone did comparisons (thanks to him). In short words :
Original
Without Colormatrix
With Colormatrix

Open the three picture in three windows (or in three tabs under firefox) ans switch from one to the other.

For me, colormatrix is definitely needed in all scripts using DVD sources :!:
What do you think ?

incredible 03-01-2005 06:55 AM

I cant access the pics linked above, also not when opeing in a separate window via dropdown mouse options.

But maybe cause on a MAC right now using IE. :?

:)

If I did understand right, in regular the color coefficients wont be handled the right way and colormatrix fixes that.

Dialhot 03-01-2005 06:58 AM

Quote:

Originally Posted by incredible
But maybe cause on a MAC right now using IE. :?

Surely :D. The picture are ok on firefox and IE.

Quote:

If I did understand right, in regular the color coefficients wont be handled the right way and colormatrix fixes that.
Yes it is. And if you compare pictures, the one with colormatrix matches exactly the original one, the other is darker.

Racer99 03-01-2005 07:49 AM

Not working here either Phil

Both in IE or Firefox.

Greg

Dialhot 03-01-2005 07:53 AM

Quote:

Originally Posted by Racer99
Not working here either Phil

Both in IE or Firefox.

Greg

The picture aren't from me and opens perfectly on my PC. There is no reason you can't open them.

By the way, the question is : what do you think about colormatrix. So I'm asking that to peoples that already tried it, and they don't need to see the picture to give the result of their tests.

EDIT: I hosted them on ImageShack (Original, without and with colormatrix, in that order)
http://www.digitalfaq.com/archives/error.gif
http://www.digitalfaq.com/archives/error.gif
http://www.digitalfaq.com/archives/error.gif

danpos 03-01-2005 08:19 AM

@Phil

I'm impressed that you didn't know about that, because of that was a old discussion between Giovane (ginoboy) and Jorge (jorel). Giovane uses the filter since this age ... :D If I'm remembered jorel discussed the color issue very long time ago (when me and ginoboy weren't kvcd.net members) here and in Doom9 board and then Wilbert did the first version of Colormatrix ... BTW, it's a very useful filter ... :D


See you,

Dialhot 03-01-2005 08:58 AM

Quote:

Originally Posted by danpos
that was a old discussion between Giovane (ginoboy) and Jorge (jorel). Giovane uses the filter since this age ...

Even if I moderate the portuguese forum I do not read all. I just lurk from time to time to see if there is a problem.

Racer99 03-01-2005 09:02 AM

Thanks Phil,

I just wanted to have a look at the samples you were talking about since I am unable to perform my own tests right this minute as I am at work. I will test tonight and post my findings.

For those of you that don't know where to find the colormatrix plug-in. You can download it from here: http://www.geocities.com/wilbertdijk...Matrix_v19.zip

Here is a post over a D9 that will further your reading.

http://forum.doom9.org/showthread.php?s=&threadid=82217

Greg

rds_correia 03-01-2005 11:22 AM

There is certainly something that needs to be explained :roll:
I use Avisynth, I have compared my VOB sources with my scripts and they are all perfect matches :roll:
Maybe I'm doing something wrong but I wouldn't know what...

Boulder 03-02-2005 05:32 AM

You don't need the filter in every encode. It depends on the source (i.e. what coefficients have been used) and the encoder you use (i.e. what coefficients it expects).

Dialhot 03-02-2005 06:30 AM

Quote:

Originally Posted by Boulder
You don't need the filter in every encode. It depends on the source (i.e. what coefficients have been used) and the encoder you use (i.e. what coefficients it expects).

When you say "depends on the source", do you mean that all DVD are different ? And then we have to test each time with and without colormatrix before to encode ?
Or do you mean that you need it for DVD but nor for avi sources for instance ?

Boulder 03-02-2005 06:42 AM

The latest DGIndex/dgdecode.dll -combination includes an info=1 parameter in MPEG2Source which can be used to determine what the coeffs are for the original file.

CCE expects MPEG2 coeffs and TMPGEnc/QuEnc MPEG1 if I remember correctly. All MPEG4 stuff are encoded with MPEG1 coeffs.

If the original VOBs contain MPEG2 coeffs and you use CCE to encode to MPEG2, you don't need ColorMatrix.
If you encode MPEG4 or a VOB with MPEG1 coeffs to MPEG2 with CCE, use ColorMatrix(mode="rec.601->rec.709").

And so on.. The docs explain more, basically it's just adjusting the parameters depending on what the input is and what the encoder expects.

Dialhot 03-02-2005 06:44 AM

Quote:

Originally Posted by Boulder
If the original VOBs contain MPEG2 coeffs and you use CCE to encode to MPEG2, you don't need ColorMatrix.
If you encode MPEG4 or a VOB with MPEG1 coeffs to MPEG2 with CCE, use ColorMatrix(mode="rec.601->rec.709").
And so on..

Okay, that's clarify a lot.
I think I will do faster with a quick test with/without colormatrix before to launch the real encode :D

Note: now we know why tmpgenc sometimes washes the colors and why for intance Rui can't compare directly it to what he obtains with HC !

Boulder 03-02-2005 06:46 AM

Quote:

Originally Posted by Dialhot
Quote:

Originally Posted by Boulder
If the original VOBs contain MPEG2 coeffs and you use CCE to encode to MPEG2, you don't need ColorMatrix.
If you encode MPEG4 or a VOB with MPEG1 coeffs to MPEG2 with CCE, use ColorMatrix(mode="rec.601->rec.709").
And so on..

Okay, that's clarify a lot.
I think I will do faster with a quick test with/without colormatrix before to launch the real encode :D

Nah, it's faster to use the parameter :wink:

Besides, you can use the hints parameter but it's a bit slow. There's also an option to use the d2v file for getting the parameters to ColorMatrix, it's faster.

Boulder 03-02-2005 06:48 AM

Quote:

Originally Posted by Dialhot
Note: now we know why tmpgenc sometimes washes the colors and why for intance Rui can't compare directly it to what he obtains with HC !

Actually I thought both of you knew about the color issues, that's why I never brought it up!

Dialhot 03-02-2005 06:56 AM

Quote:

Originally Posted by Boulder
Quote:

Originally Posted by Dialhot
Note: now we know why tmpgenc sometimes washes the colors and why for intance Rui can't compare directly it to what he obtains with HC !

Actually I thought both of you knew about the color issues, that's why I never brought it up!

Between knowing that there is an issue, and knowing that someone already find/developp a solution, there is a difference :-)
And Colormatrix isn't so old it seems to me.
Quote:

There's also an option to use the d2v file for getting the parameters to ColorMatrix, it's faster.
I know I saw that in the doc but... can you just give a example of script ? What is the mpeg2source line and what is the colormatrix line to have a "full automatic" color compensation (if this is possible).

Note: I have doubt it can be faster than doing a test because it depends on the encoder as you say and there is no way avisynth can know what is expected by the encoder you plan to use :D

Boulder 03-02-2005 07:36 AM

Quote:

Originally Posted by Dialhot
Quote:

Originally Posted by Boulder
Quote:

Originally Posted by Dialhot
Note: now we know why tmpgenc sometimes washes the colors and why for intance Rui can't compare directly it to what he obtains with HC !

Actually I thought both of you knew about the color issues, that's why I never brought it up!

Between knowing that there is an issue, and knowing that someone already find/developp a solution, there is a difference :-)
And Colormatrix isn't so old it seems to me.

Next time I'll open my mouth earlier :wink: I thought you knew since you visit Doom9 from time to time.
Quote:

Quote:

There's also an option to use the d2v file for getting the parameters to ColorMatrix, it's faster.
I know I saw that in the doc but... can you just give a example of script ? What is the mpeg2source line and what is the colormatrix line to have a "full automatic" color compensation (if this is possible).
I'm unsure how it works since the docs say that the mode parameter is not used if d2v or hints is used. However, tritical, who added the hints parameter, says that hints=true means that the conversion is done if necessary depending on the hints and what you set the mode to.

So if it works like it should, it would simply be

MPEG2Source("path\clip.d2v")
ColorMatrix(d2v="path\clip.d2v",mode="rec.601->rec.709")

for CCE. If the coeffs in the input file are rec.709, no conversion is done - if the d2v parameter works like hints. This must be checked, otherwise it's pretty much useless.
Quote:

Note: I have doubt it can be faster than doing a test because it depends on the encoder as you say and there is no way avisynth can know what is expected by the encoder you plan to use :D
If you use CCE all the time, you know that you need rec.709 coefficients. To me it's faster to check what MPEG2Source says, if it's rec.601 or something very close to that, I use ColorMatrix. Otherwise I can leave it out.

Dialhot 03-02-2005 07:53 AM

Okay, now that I am fully in the subject I understand more the docs I read before without giving attention :

D2V_Format_v08.txt :
Quote:

E. The layout for each GOP line is:

gop matrix file position vob cell flags flags ...

[...]
The matrix field is the currently applicable matrix_coefficient
value (colorimetry)
Colormatrix.htm :
Quote:

For people who are interested, it is this (and consequent) line(s) in the d2v file

800 5 0 8210 0 0 32 32 92 b2 b2 a2 b2 b2 a2 b2 b2 a2

I've made the colorimetry info bold
So faster than using the info=1 in mpeg2source, you just have to open the d2v file.

Boulder 03-02-2005 08:23 AM

And it would be even faster if the plugin just read the very first line and used the value that's entered there. At least according to the fact that it crashes if the information changes during the d2v file, it reads every one of them.

nicksteel 03-02-2005 08:48 AM

:?: Would this work the same with a D2V from a MPEG2 capture (PVR-250)?

Some of my encodes appear darker than original captures and I would like to try this.

I use D2V - AVS - TMPGenc


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