Preparing this Rec.601 YV12 clip for Rec.709 MPEG-2 encoding

[fvisagie]

@poisondeathray,

levels(0,1,255,0,237,false, dither=true)
invert
hdragc(max_gain=2, coef_sat=0.75)
invert
levels(12,1,255,0,255,false, dither=true)
hdragc(max_gain=2, coef_sat=0.88)
tweak(sat=1.2, coring=false)

Yes first invert + HDRGC was for cloud region ,next was for darker grass region .

Another interesting thing you did here was to desaturate by ~20% while using HDRAGC, and then to resaturate by ~20% afterwards. Why was that?

Also, why did you use Levels() with coring enabled, as opposed to coring=false or ColorYUV()?

Thanks,
Francois

[poisondeathray]

Another interesting thing you did here was to desaturate by ~20% while using HDRAGC, and then to resaturate by ~20% afterwards. Why was that?

HDRAGC saturation default is usually too high in my experience. I almost always adjust coef_sat lower. I just "eyeballed" it, again no science . The filter adjusts saturation along when adjusting levels (it's not like a Ylevels)

The reason for the difference in the calls is I felt the sky should look more "blue", so the value is "less desaturated" in the sky region vs. the foreground region. Again, very subjective, no science . Tweak adjusts saturation everywhere, not in regions or via masks . Try playing with the coef_sat values for each different call and examining the effect and you will get a better idea of what it does

Also, why did you use Levels() with coring enabled, as opposed to coring=false or ColorYUV()?

Look closely again: the "false" means coring=false .


Again, the only "objective" thing that everyone will agree on is to bring Y' mostly between 16-235 ; everything else is "subjective" and you can make it "look" however you want

[fvisagie]

Spot on. I was interested more in understanding the principles of the approach you took than in science, many thanks.

Look closely again: the "false" means coring=false .

I must have been getting tired...

Edit: I'll probably end up using YLevels() as you suggested earlier, or ColorYUV().

Thanks for your patience and all the inputs, you've been a really great help.

[sanlyn]

-30-

[2Bdecided]

Has your VideoHelp account been hacked sanlyn?

You seem to be posting random messages to old threads, and many of your old messages have been deleted and just replaced with "-30-" - what on earth is happening?

I would PM you, but you have PMs switched off, and if I email you and your account has been hacked that will reveal my email address to the hacker.

David.

[jagabo]

Sanlyn got pissed that nobody agreed with him in a thread about HDMI cables and decided to retaliate by removing all his posts.

https://forum.videohelp.com/threads/363156-Does-any-cheapo-HDMI-cable-suffice

Presumably, the "right forum" would be one where everyone agrees with him.

[El Heggunte]

Sanlyn got pissed that nobody agreed with him in a thread about HDMI cables and decided to retaliate by removing all his posts.

https://forum.videohelp.com/threads/363156-Does-any-cheapo-HDMI-cable-suffice

Presumably, the "right forum" would be one where everyone agrees with him.

Triple-LOL — I thought that leeperry was the only one of the kind

http://forum.doom9.org/showthread.php?p=1156749#post1156749

[sanlyn]

With all respects to jagabo, who knows more about video than I ever will and from whom I've learned almost everything I used here and elsewhere, and to whom I am eternally grateful...the right forum is not one where everyone agrees, but where ideas are not distorted and run into the ground by hooligans without giving them a try. That aside, almost everything I've posted came from what I learned from jagabo and a few others, and use principles and methods duplicated everywhere. And a lot of it was wasted bandwidth.

I was PM'd by some users to leave some of it as-is. The rest appears to be of little use.

[2Bdecided]

Oh dear, thanks for the info jagabo. That's a shame. Unlike sanlyn, I don't keep a careful archive of useful AVIsynth scripts - I just trust the search functions here and at doom9 to find them for me again when I want them. That's me screwed then!

Sadly the internet archive is of limited help.


FWIW you can force HDMI to be "on the edge" of working such that only a few pixels in a frame (and/or only pixels of a certain colour) will be affected. The resulting small twinkly artefacts are sometimes easily missed. But in that thread pandy really is right - and if you consider that many (in Europe, most) sources are HDCP encrypted, that makes it even harder for a cable to cause "subtle" changes. It's not at all true that "digital is digital" - digital can go wrong in many ways - but the failure modes are usually well understood, measurable, and explicable. There are certain HDMI implementation issues that can cause the changes sanlyn reported (I think those were pretty well covered in that thread too), but cables are barely relevant to them.

Cheers,
David.

[sanlyn]

Goes beyond wire. Too much blind faith in numbers around here. I'll post art, perception, and stuff that can't be measured where it belongs, elsewhere. No sense being a source of contention and I don't need the aggravation. I left a lot of posts, too much of it was the same scripts over and over. I'll restore some of it without the verbiage and philosophy, which nobody needs anyway. Left some stuff intact for people who PM'd me.

[2Bdecided]

I don't know about measuring art, or even preference, but perception can be measured pretty well. IMO until someone accepts double-blind testing and the need to objectively prove that they really see/hear a difference, there's little point having the conversation. Expectation bias and placebo are too powerful to ignore them. Once accounted for, you can design experiments to test human perception that deliver thresholds of detection and performance that are right at the theoretical maximum of the known biology. In other words, knowing what's physically present in the human sense organs gives an idea of the best that they could do, and studies into human perception demonstrate that we can reach those limits.


Up until the digital to analogue conversion, digital video is just "numbers". If the numbers are truly identical, then the video is truly identical. To believe anything different is to believe in magic. It's easy to overlook sources of error, but that's a problem that can be resolved by rational investigation, rather than resorting to something that is effectively a belief in magic.

It's interesting that you found the videohelp forums to be so inflexible to your belief. I regularly post in an audio forum that has such rules codified in the founding principles (rather rare in the audio world), but generally a belief in magic (expressed in other ways, but that's what it comes down to) is quite prevalent on many internet forums.

Cheers,
David.

[El Heggunte]

<Overdue Off-Topic>

Up until the digital to analogue conversion, digital video is just "numbers". If the numbers are truly identical, then the video is truly identical.

That's correct.

To believe anything different is to believe in magic.

Sorry, sir, but that does not compute. Unless you have (unconsciously, who knows) conveniently and ideologically re-defined the meaning of "magic".

JMNSHO, but the pseudo-rational and pseudo-scientific claims of the materialist Weltanschauung is some centuries old already, and their madness has gone on long enough -.-

</Overdue Off-Topic>

[2Bdecided]

I don't understand what you're saying.

Let us define two functions f1 and f2
Let us define 2 things, A and B.
C=f1(A)
D=f2(B)

If A=B and f1=f2 then C=D.

Or in English, if A and B are the same, C is a function of only A in exactly the same way that D is a function of only B, but C and D are not the same, then something is wrong. Either
1. A and B are not really the same, and/or
2. C and D are really the same, and/or
3. the functions f1 and f2 are not identical, and/or
4. C is a function of something in addition to A (i.e. not only A) and/or ditto D viz B.

If A and B are the same, C is a function of only A in exactly the same way that D is a function of only B, but C and D are not the same, and none of those things are wrong, then you are left with the process including magic. Or whatever you want to call it.

The most likely explanation in the kind of things we're discussing is 2: C and D are the same. A human observer thought they were different, but that was just placebo / expectation bias. No magical explanation required. You can check this fairly well using double-blind tests.

The other plausible explanations are A and B being different (i.e. the source video being different), or f1 and f2 being different (i.e. the cables, or the way equipment reacts to them, being different). These are plausible and testable. You can make the source videos the same. You can verify that the data decoded at the HDMI input from both cables is the same. If you can do all that properly, and pass double blind tests to prove that C and D are different, then it's worth trying to unpick things - but I still wouldn't expect magic to be the cause. It's going to be 1, 2, 3 or 4 at play in some respect. If it's not, hello magic! Hello digital data that changes magically! Goodbye digital computers! Goodbye internet! Goodbye to this and every other forum post!

Cheers,
David.