TMPGEnc CCIR601 option REVEALED!

[adam]

Shadowmistress at the moment your pics aren't showing, but I think I already described why leaving this option unchecked appears not to have any effect, even on a source which does not need to be compressed any further.

Simply put, pc's use a wider luminence range then tvs. This is certainly not a universal rule, but generally speaking when you access your mpeg (which now as a matter of fact must conform to 16-235...that is all that is supported) it is going to be decoded to RGB and expanded to 0-255. This makes perfect sense, because if you don't use the pc's luminence range, then it looks wrong on the pc, even though it would look perfect on the tv. So after compressing your luminence levels once (option unchecked in TMPGenc) you are loading that mpeg into TMPGenc again. TMPGenc only accepts RGB sources. So your luminence levels are being expanded out to 0-255 again. You compress them again, then try the test again. TMPGenc expands them again, you compress them again, etc...etc... That's what I mean by rinse, wash, repeat. Everytime you compress it you just expand it again in your next encoding test. That is why you don't see any difference but trust me, TMPGenc is compressing your luminence levels each time. Yes I think we agree with WHAT to do in WHICH circumstances, generally. But I do think I've accurately described exactly what TMPGenc is doing and this is a universal thing not just with TMPGenc, or with mpeg encoders, but with any codec or filter that converts from RGB to YUV. The outer levels get clipped, if there is nothing there then you are fine. If there is something there, then you've got to compress it first, then you can trim the fat. Failing to do this throws out luminence data. Compressing when you don't need to limits the dynmainc range of your luma...in noobie speak that means black isn't quite black and white isn't quite white.

Senseless setting names, poor translation, end of story.
Switch to something that is written in English, not psuedo-English.

I believe its called Engrish. But like I said, this setting is no different than any other luminence level setting in any other encoder. I bet anything that you are doing multiple RGB->YUV->RGB conversions before you even hit your encoder, and for all you know, you may be doing them incorrectly.

[Shadowmistress]

And the award for "Doublespeak" in the "Useless complication of sentences" category goes to.....

[adam]

I dumbed it down for you as much as I can. I can't help it that lum-in-ence has three syllables.

You are asking why compressing it over and over again doesn't change anything. What I am explaining to you, apparantly poorly, is that you are compressing once, then expanding, then compressing, then expanding, etc... The reason you don't see any difference is because you are not changing anything. I cannot make you perform a valid test. Until you do one you will never understand this.

[Shadowmistress]

A. I performed the tests.

B. Before (in previous threads) you were saying and convincing others that if you keep leaving it unchecked it will keep getting compressed further. Now you're saying the exact opposite, that it will not change. You didn't even look at my links/pics.

C. I understood that tmpgenc internally expands to 0-255 a long time ago and not by your explanations. I don't care what it does internally, the only thing I care about is how it spits it out.

D. luminescence is a four syllable word. lum-in-ence is not even in the dictionary.

[lordsmurf]

shadowmistress, I like you, don't fight with adam and get yourself in trouble.

That award is funny.

In adam's defense, you ARE talking about techie things at this point in time. It's nearly impossible to put it in kiddie words.

[adam]

A. Yes, and you keep ignoring me when I tell you that you are interpreting the results incorrectly.

B. If you keep feeding it a 16-235 source it will keep getting compressed. You are not doing this because you apparantly aren't listening to me. Whether it repeatedly gets compressed is not so much the issue anyway, since people don't typically recompress the same image. What I am saying is that you have already screwed up on the first and only encode when you leave the box unchecked when your source is 16-235. Need I remind you what YOU have said all along?

Thanks for proving it. Unchecked box does nothing!

C. But TMPGenc does NOT internally expand to 0-255 unless you feed it a YUV source. That is why you have to actually set this box according to what your source actually is. I have repeatedly explained how to set this option and when to do it. Regardless of whether you like or understand my description I can assure you that it is accurate.

Once again, for a 16-235 source the box should be checked. For a 0-255 source the box should be unchecked. This is what I have said all along, and again this is what you have been saying:

Unchecked box does nothing!

D. Actually the word is luminance so we're both wrong but I'm closer. Yes its a word and its a technical term so it is not subject to debate.

[FulciLives]

I think we need jaxxboss to come in here with his famous (or is that infamous) words of advice ...

I farted



- John "FulciLives" Coleman

[Shadowmistress]

Debate? Ahhhhhhh! No more!

Well the next time a newbie asks, here's how i'll answer:
"What does that box do that says YCbCbr and should I be checking that?"
"What range is your source in?"
"I dunno"
"Leave it unchecked. If you don't like the contrast you get, use a filter"

[MrMoody]

The next noob that asks, point them to the first post in this thread.

Anyone disagree with anything I said in there? Speak up. I believe the advice there is correct.

[Shadowmistress]

Presented to MrMoody for a comprehensive explanation to a noob

[adam]

MrMoody I believe it is all correct also, but maybe you should specify that you are talking about loading those sources directly into TMPGenc, and leave it at that.

For instance, if you frameserve a DVD through DVD2AVI it has an option to select whether it outputs 16-235 (tv scale) or 0-255 (pc scale.)

Also if you are using a chain of programs (ie: DV->NLE->Avisynth->encoder) then the source colorspace is pretty much meaningless.

Shadowmistress, CCIR601 is an entire broadcasting standard. You cannot expect it to be explained in a nutshell, or in terms that any newbie would understand. I think MrMoody's little guide is about as concise as you can make it, so it makes for a nice reference. But if you are a self admitted newbie on this matter then you should not be giving advice at all, much less arguing about how this stuff works.

[Shadowmistress]

Yes I am a noob, no I have no clue how things work or why.
The only reason I spoke up at all is because I knew what the bloody box did. The only reason I knew that was from doing my own tests. I was never interested in the explanation behind it.

[adam]

That's fine, but the point of this thread WAS to get an explanation behind it, and that's what the rest of us have been trying to do. It seems that the rest of us have all been in agreement from the start as far as I can tell.

So, moving on....

[daamon]

Lock it there. Someone. Please.

EDIT: Sorry - I meant "Leave it there" - Freudian slip...

The problem has been addressed and (well and truly) explained and nicely summarised to everyone's satisfaction. I certainly found it useful.

Now's a very opportune point to draw a line under it.

Else I can see this thread turning into a battle of wills and totally getting off the point of the topic.

[Shadowmistress]

Um, sorry but the title of the thread leads me to believe it is about the box.

I don't mean to flame you because you obviously know alot about alot, but one thing I notice with some experts around here is that they forget what it's like to be a newb and lose the abilty to dumb things down.
That's ok, don't get me wrong, I'll gladly do some self education to meet you on your level, just as long as from time to time you can come down to mine.

[daamon]

We were all noobs once. And, yes, sometimes it's easy to assume that things are easier coz you already understand them.

But, I think Adam's point was that there are some things (this being one) that are difficult to noobify (find that in a dictionary) either at all, or in an immediate response, or without being able to have a face-to-face conversation.

I sometimes teach for a living, and there's no substitute for being in the same room as someone to explain a tricky concept.

The spoken word and the ability to quickly bounce back and forth can't be bettered - typing in forums is the best we've got but sometimes it's just not enough.

[adam]

Like I said, moving on...

There is no reason to lock this thread. For those who want to discuss this "box" let's continue to do so.

[Shadowmistress]

Moving on...

[daamon]

Sorry... Couldn't resist!!!

[FulciLives]