abrupt highlights clipping

[Alexander Ibrahim]

Originally Posted by Bill Ravens

As for [Steve Mullen's] contention that conversion introduces chroma errors...he doesn't know what he's talking about.

I don't know the comment Steve Mullen made, but going on your refutation:

Steve is half right. Conversion always introduces all sorts of errors- including chroma errors. Usually its rounding/aliasing errors because the color spaces don't have the same gamut- so your colors may shift slightly.

(A bad conversion algorithm can wreak havoc- but last time I saw that was ... I can't remember a LONG time ago. Pre 2000.)

You are right Bill, in that that doesn't seem to be the main culprit in this case.

[Glenn Chan]

Originally Posted by Alexander Ibrahim

If the developers can screw up something that straightforward then what else is wrong?

Well many software scopes are inaccurate. FCP has some errors... its scopes don't always show superblacks correctly, and sometimes the broadcast safe filter does not render out (but it will show in the preview).

I think these errors stick around because very few people need accurate scopes (it's only broadcast delivery where you really need them), and of those people they likely have real hardware scopes anyways.

2- Part of the problem is inherent in the way Vegas handles levels. Unlike other NLEs, manual colorspace/levels conversions are in some cases required. Most NLEs handle that stuff automatically.

For whatever reason, and not a reason I understand, using the Computer RGB to Video RGB performs an excessive amount of attenuating of the hilites and shadows of a native .mxf file in V8. All you have to do is look at the histogram. You're right guys, the image looks, and is, washed out.

1- Performing a computer RGB to studio RGB conversion isn't appropriate in this situation.
2- The video preview may not be accurate.

WHATEVER the camera does, if delivery is via NTSC, , regardless of the processing precision, 8 or 32 bit, then set it for RGB16-235.

I disagree. This will give you the wrong results if you are in 32-bit and render to 10-bit SonyYUV (and possibly some other situations).
You should consult a table like this one since you need to know what the codecs are doing:
http://glennchan.info/articles/vegas...or/v8color.htm

2- I think you're getting tripped up in assuming that Rec. 601 is associated with studio RGB, and that Rec. 709 should be associated with computer RGB. It's not true.

*Anyone can download ITU-R BT. 601 and 709 for themselves. They don't specify a standard conversion to R'G'B' except for editing purposes (nor would that make any sense).

[Bill Ravens]

10-Bit Sony YUV is not a distribution format. I stand by what I said. I associate REC 601 with DV and older SD formats. REC709 is more related to HD(v) formats. REC 709 allows for RGB 0-255, REC 601 does not.

[Glenn Chan]

You can go through the 10-bit SonyYUV codec to SDI to say, a digital betacam (SD) or HDCAM (HD) deck. That is a distribution format in the sense that it goes to the broadcaster.

REC 709 allows for RGB 0-255, REC 601 does not.

This is not true... you can read ITU-R BT. 601 and 709 for yourself.

The studio versus computer RGB stuff is a Vegas thing... not ITU-R.

2- Vegas is also confusing because not all HD formats use a 0-255 range. Cineform doesn't, most codecs in 8-bit don't, etc. etc. You need to consult a table (or some other equivalent method). There's no connection between SD/HD and whether the codecs use computer (0-255) or studio (16-235) levels.

[Glenn Chan]

it seems nobody has complete understanding of the relationship between the EX1 scopes vs Vegas scopes, especially in the context of Vegas 8bit vs 32bit processing, and/or colour space conversions - not to add the extra complication that the PAL video format introduces as opposed to NTSC format.

Piotr, here are my articles on how color spaces in Vegas work.

http://glennchan.info/articles/vegas...lorspaces.html <--Read that first, then:
http://glennchan.info/articles/vegas...or/v8color.htm

I've done the tests (including checking on real scopes) to arrive at that information. It's how Vegas works.

My first post in this thread (#220) gives you the relevant info to handle the color space part of your test. The only thing I've left out is that you might need to change the output end setting on the Levels filter lower. That is because the Y'CbCr color space contains many colors that lie outside typical R'G'B' space / the camera might be shooting some weird Y'CbCr values.

[Piotr Wozniacki]

Glenn, Alexander, Bill and Bob;

Thank you so much for your response to my (a bit bitter - sorry for that) post. Please get me right: I'm not _demanding_ that any forum member is _obliged_ to answer complex questions. In fact, it's SONY (the camera manufacturer), and Sony Creative Software (Vegas producer) who should provide us, the licenced users, with enough information to never run into doubts like this.

As a side note: I've been selling, implementing and supporting the highest-end CAD/CAM/CAE software since the mid-1980's and believe me, leaving a customer on his own while facing similar dilemma would have been unthinkable!

And yet - even though both the hardware we're discussing here (the XDCAM EX CineAlta) and the software (Vegas) are both _Professional_ products - getting appropriate support from Sony is impossible. Hence my bitterness...

The more we're grateful to forum members like you for trying to help us, the less-knowledgeable members, by sharing your in-depth expertise for free...

Back to the merits:

Glenn, I have read your articles you have provided the links to, as well as your, Bill's, and other's posts here and on the SCS Vegas forum. Unfortunately, you guys not always agree in your interpretations of the matters involved...

One thing that has never been addressed (as it _perhaps_only applies to PAL users) is what I observed, and enquired about, many times before:

- OK, so the Vegas preview window is not a thing to blindly trust; what's important is my final render. But in the "Advanced video" tab of any "Render as..." template, one can choose the "Video format" to be either NTSC (the Vegas default), PAL, or Component. Now, this can dramatically change the look of my final renders!

For the time being I'd be comfortable enough if I knew for sure that the following workflow with my EX1 mxf's is OK:

- stay in 8bit video all the way through and not apply any colour space conversion, even though the preview window looks washed-out

- make sure the Video format is set to PAL in the final render.

Well, I know this has made the equation even more complicated, but I'd appreciate an explicit answer. TIA!

Piotr

[Bill Ravens]

Piotr...

AFAIK, my workflow is to stay in 8-bit until I'm ready to render. Then I convert to 32-bit for final render. I ALWAYS carry along a colorbar for 2-secs in every render and check the pluge aginst the WFM after rendering. This is de riguer until I get my head around which codecs do what.

In the end, it's really up to each of us to test our own workflow from start to DVD production and viewing on a consumer monitor.....or whatever our chosen distribution media is. Once we're satisfied with the results, we can reproduce that workflow, exactly. If the workflow changes, repeat the testing ...all the way thru to the end.

There's tons of advice available here, much of it is wrong, my own advice included. There are so many variables and places to get tripped up in one's workflow, this part of the process really needs to be methodical and repeateble. Bad results or "flyers" need to be ignored. There's too much else to focus on. I've listened to other people without testing all the way thru to distribution, before, and it's gotten me in trouble. If you have a paying customer, and you deliver late because your workflow is erroneous, you've just lost a customer.

BTW, before I retired, I was a daily user of CAD/CAM(Solidworks, Pro-E and Unigraphics) Now THERE's a mess!!

[Steven Thomas]

Bill,
do you have Cineform NEO HD?

Currently I have NEO HDV, which only supports up to 1440x1080.

I'm thinking about upgrading to NEO HD, but I want to make sure I can benefit with this upgrade over just staying with the mxf files.

I'm well aware of the overall benefit of Cineform, and some day I hope to capture directly to their codec via their future SDI portable recorder (I'm really looking forward to this!).

My normal work flow usually involves staying in Vegas 8.0b using internal plugins,color grading, effects, ect.. so this implies only one render at the end to my final distribution format (DVD, or Blu-ray). When going to DVD, I usually frame serve to Procoder. Vegas 8.0b makes great looking m2v files for Blu-ray.

Will I benefit from NEO HD using this work flow?

[Bill Ravens]

I upgraded to Neo HD a few months ago, primarily for the 1920x1080 size capability. Honestly, I'm undecided about the utility of CFHD. I lose timecode by transcoding to CFHD. It makes a really great intermediate, and usually render to CFHD in my process. I guess, the jury's still out on this choice.

[Glenn Chan]

what's important is my final render. But in the "Advanced video" tab of any "Render as..." template, one can choose the "Video format" to be either NTSC (the Vegas default), PAL, or Component. Now, this can dramatically change the look of my final renders!

I'm not seeing that on my end.

What are the steps you are taking?
What codec?

What program are you using to view those files?

[Piotr Wozniacki]

Glenn,

Here is the grab with the setting I mean; if I choose anything other than PAL or Component, the colours of my HDV final renders are less saturated, and the dynamic range narrower, than with the source HDV clips as played in any MPEG-2 software palyer - including WMP or Nero Showtime.

Also, I had to create my own Blu-Ray templates, as those supplied with Vegas all had NTSC as the video format (even the 1440x1080/50i or 1920x1080/50i ones).

This is one of the things that show Vegas has been developed with mainly the NTSC users in mind.

[Glenn Chan]

I'm not seeing that on my system- renders between NTSC and component look the same.

Also, I had to create my own Blu-Ray templates, as those supplied with Vegas all had NTSC as the video format (even the 1440x1080/50i or 1920x1080/50i ones).

My 50i templates show component or unspecified.

[Michael H. Stevens]

Glenn: I have read all the links but still would like some specific info related directly to the EX1 such as:

1) If I capture with Clip-Browser, what color space are the mxf files in? (To me they act like computer RGB)
2) If I set my project to 32bit how does that change the mxf files color space?
3)If I capture with Cineform I have a studio RGB, right? So how will footage look or act different from mxf files as in 1 above.
4) If I render out for Blu-ray what color space does the burner get or expect?
5) Do these question indicate I'm totally wacko?

[Piotr Wozniacki]

Originally Posted by Glenn Chan

I'm not seeing that on my system- renders between NTSC and component look the same.

Am I hallucinating? Bob, your're PAL - could you please render a few secs of an mxf into 1920x1080/25p in two versions: PAL and NTSC as video format (as per my post above), and compare the resulting colours with those of the input clip? TIA!

[Bob Grant]

Originally Posted by Piotr Wozniacki

Am I hallucinating? Bob, your're PAL - could you please render a few secs of an mxf into 1920x1080/25p in two versions: PAL and NTSC as video format (as per my post above), and compare the resulting colours with those of the input clip? TIA!

No problem but before I do I think that using either PAL or NTSC would be a mistake, there's no such thing as PAL or NTSC in HD, in SD there is a difference between REC 624-2 for PAL and NTSC (slightly different colourspace). There is no such difference in REC 709, Vegas uses the Component profile for all HD mpeg-2 encoding. This would explain why you're seeing a difference, basically you're changing something that you shouldn't.

In fact the use of the terms PAL and NTSC in relation to HD is wrong, it makes more sense to use 50Hz / 60Hz or Region 50 / Region 60.