Colour compression and spaces

[Craig Longman]

I've been mulling over colour a lot lately, and would like a few points clarified if anyone can. I am currently using Sony Vegas Studio 10, not the Pro version. With the BorisFX package, I find that most of the items missing are replaced by that, and I get a number of other useful things also.

However, about the colour stuff.

I use a Canon XL1 right now, which uses 4:1:1 colour compression. My first concern is, this 4 pixel colour 'mixing' only happen(ed/s) at the record point, right? Once I have the clips sucked off via firewire and stored, I'm using per-pixel colour in Vegas, no matter what? Primarily, I'm trying to determine if re-encoding to another format that uses 4:4:4 before doing any editing/FXing.

Second, I've been slowly absorbing this article:

Color spaces and levels in Sony Vegas 9

And I'm really unsure about a few things. First off, in Vegas Studio, I can find nothing to indicate/alter what colour level I'm working in, and it seems to matter seeing as things can be decoded differently depending.

I'm really quite speechless that this whole thing is such a mish-mash-mess. Sony really should have put some thought into it, it's ridiculous. I really had trouble understanding why my footage looked so very different on my computer versus direct to the television. But a simple 'Studio to Computer RGB' output filter fixes it. What the hell? Where do they think the normal non-external output device is going? I almost looked at taking my camera in to be serviced the colours looked so washed out. I can see not choosing it for an external device, which might be an actual monitor or possibly a second windows display, but the window preview?

That being said. When I've decoded my DV footage, do I need to be concerned with the washed out colours in the FX stages? Should I _always_ add a' Studio to Computer' corrector to get decent colours for chroma keying? Or is it just being "flattened" again before going to the preview window. Perhaps this is something that re-encoding to a different format would help with.

Also, does anyone know how to determine what Vegas is doing with media? The article referenced above seems to indicate that image sequences (jpegs at least) are, in fact, in Computer RGB mode, but I've played with a few and it seems adding a Studio to Computer correction still makes them look better, the blacks appear washed out with it added to the output fx. But, I'm not sure if my untrained eyes are simply seeing darker blacks and thinking it's good, when in fact it is just crushing the already Computer RGB colour. Is this just a case of having to sit down and bring in some colour bars via each and every method and try and guess which one? Then I guess encoding each method you use and again, try and guess which one is right. Very tough when your monitor hasn't been professionally calibrated.

Anyway, this really is (or seems to me to be) one of the weakest areas, and the least well documented. Any and all pointers/info/comments/chides/reprimands would be duly appreciated.

Thanks.

[Robin Davies-Rollinson]

Craig, I'm glad that you've asked this question - there are just too many variables in the chain I've found (I'm using the same version 10 as you)
Apart from that, it's an excellent little package and punches well above its price compared to other NLEs in the same price bracket.

[Ken Jarstad]

It looks to me like you are dealing with issues concerning "gamma". To state it a simply as possible television display gamma and computer video display gamma are different. Whenever I play a video on my PC with Windows Media Player it always seems a bit dark compared to playing on a television - and the chief difference is do to differing gamma standards. Although Sony Vegas' preview display is a reasonable portrayal of what my video will look like I prefer to connect a small HDTV via HDMI cable to my secondary video card output. Since I am displaying video on a display designed for doing that it already has the proper gamma and I have a greater expectation that my product will display properly on any television.

Assuming I have understood your question I would point you to a somewhat dated but technically accurate article:
Gamma FAQ - Frequently Asked Questions about Gamma

Scroll down to question 16. Questions 18 and 19 might be useful, also.

[Craig Longman]

@Ken, it's not gamma. If you look at the link I posted, Vegas does use Studio RGB for it's internal representation, and there the legal values are 16-235 for black-white instead of Computer RGB which is the full 0-255, to allow for some over-max and under-min values. Vegas (supposedly) opens some in Studio, some in Computer. If you view the Studio on your monitor, in the preview window as a docked window, not as a full-screen secondary monitor, you will see washed out colours until you convert from Studio to Computer. It really even seems to me that you can see the difference in the trimmer, it seems to do the conversion automatically, but the preview doesn't.

Thanks for the link though, it does seem to have some nice info on it.

Now, gamma, 32-bit full versus video and the whole 1.0000 versus 2.2222 thing is another kettle of fish that I didn't want to open just now... =)

@Robin it really is. I tried all the "consumer" versions out, and Vegas stood out for me. Their now v10 is way more generous that I would have expected, with 10 tracks and all.

Course, the other thing I'm doing is writing some FX plug-ins, and their API leaves a LOT to be desired.

But, I didn't mean to sound too negative, I like Vegas a lot, it just seems like this whole business is way, way more complicated than it should be, in Studio or Pro.

[Ken Jarstad]

Craig, if you are writing plugins then you have a greater technical expertise than I do. You sometimes can't tell the tech level people have, writing on forums. All I can tell you is I just completed my first serious project, my granddaughter's wedding, in VMSHDP10 with the setup I described and the results were great - made 11 DVDs and 6 Blu-rays and nothing in my project seemed washed out - except for the horrible back-lighting I had to deal with <grin> which VMS handled pretty well.

[Craig Longman]

On the plus side, for all the preview looks all washed out, it does seem like the MPEG-2 encoder expects Studio RGB, so yeah, it should look great when rendered that way. But I think if you dropped the "Studio to Computer RBG" FX plug-in into the output/preview window, you'd find the preview looked a lot more like what you were expected and/or saw on the final DVD output.

And, although I can write DXTransform code, doesn't mean I understand all the video/colour stuff well, thanks for the response. In fact, I'm also going to be asking the SDK contact what I need to know to be aware of the differences internally.

What I was saying could definitely have been interpreted as gamma, although I'd have expected gamma issues to make things seem darker while being flat, at least PCs seem to be dark compared to Macs.

Anyway, hoping someone(s) can shed some/much light on all this from a user perspective.

[Seth Bloombaum]

If you've not yet seen them, Cineform's blog on the subject, and Glenn Chan's discussion on his website are both helpful. I recommend reading the Cineform piece first as an intro, then Glenn's piece goes into the different treatments that Vegas gives various codecs.

Although a little developer-bashing is always good sport, Sony did not invent the NTSC color system that parks black at 7.5% of white; we all have to live with that accident of history. I'm sure there were good reasons at the time. Having said that, I too wish that the indications of 16-235, 0-255, 7.5% IRE and such were clearer in Vegas.

[James Binder]

I'd like to hop in here with a question if I may:

Is it only certain types of footage that require studio RGB to computer RGB filter/plug for proper viewing in the preview window? (not referring to viewing on secondary or external monitor)

HDV definitely looks very washed out -- and benefits from applying the filter

h264 (QT's from t2i) on the other hand -- look very good and don't seem to need the filter.

What's the word?

BTW -- I too think Vegas does a lousy job of making this subject clear. Certainly, there must be something that can be done (on Sony's part) that will make the preview window viewing accurate!! How does the other NLE's do it?

[Craig Longman]

@Seth =) I realize Sony didn't invent the two types, but it seems so haphazard as to which is used. And to make matters worse, it seems to _change_ depending on the internal colour level used. Those articles by Glenn are awesome, and the basis for what little understanding I do have. However, as I point out, it seems wrong now as the image stream I imported _looks_ washed out to me and seems to need the Studio to Computer filter. Which is in contradiction with what Glenn indicates image streams should be.

It really does need _some_ sort of indication, it is ridiculous how vague and shrouded this relatively key information is. If I'd been doing my grading based on the preview window, I'd have a crap video at the end of it all... well, relatively compared with what I could get now that I see the real colour properly.

I don't even care really if it actually "does the right thing", but if it just indicated _what_ it was doing, I am capable of figuring out what I wanted and adjusting accordingly.

@James what you see seems to coincide with what Glenn's article says; DV & HDV are studio in 8bit/32bit video (but computer in 32bit full-range) and QT are (for the most part) computer RGB.

Some much to read here, I'd like to recap the basic questions.

1) How do I determine if I'm in 8bit, 32bit video or 32bit full-range colour mode?
2) How do I determine if the stream I'm viewing/using is?
3) Does the washed out colour affect things like chroma keying? Should I convert the clip from Studio to Computer before pumping it to the chroma key fx plug-in?

There were a couple other Qs in the OP, but there seems to be some interest in this colour level bit, so I'll focus on that and ask the others in another thread.

[James Binder]

Originally Posted by Craig Longman

@Seth =) If I'd been doing my grading based on the preview window, I'd have a crap video at the end of it all... well, relatively compared with what I could get now that I see the real colour properly.

There's part of the issue. If going out to a broadcast monitor, TV, etc, these issues are avoided (to the best of my knowledge). Im my case, I'm using a 32" HD Sony LCD as my primary monitor (timeline, preview window). As such, I like to use it for color grading >> however, knowing the accuracy of what you're viewing is problematic. I do have a secondary monitor, but had hoped to use only one screen for all!

Nevertheless and again -- I'm thankful to people like Glenn and others who have written about this -- however, do the other NLE's have this issue? If not, why not?