Downconversion still soft ?

[Bob Zelin]

How can you do critical color correction of HD material on a SD monitor – soft or not ? What SD monitor do you own – a Sony BVM series?

Bob Zelin

[Dan Silber]

I own a calibratable SD broadcast monitor, a JVC, not a Sony.

I currently grade and edit HDV and DVCProHD footage on a MacBook Pro and have the SD monitor hooked up via an RGB -> YUV converter (plugged into my DVI out) as a secondary monitor running at PAL resolution and scan rate. The image ist crystal clear and it all plays back that way in realtime.

However, I now want to hook up a 24 LCD to my laptop for more screen space to work on. This means loss of the DVI port because it will now be used to drive the LCD screen.

So now, in order to then be able to monitor a video signal properly, it has to come from a video card inside a Magma chassis hooked up to the broadcast monitor – right?

Basically, I want to know if DeckLink SP’s downconversion is as good as Apples “Digital Cinema Preview”, which is my current setup.

Any thought, please?!

Thanks!

[Bob Zelin]

I can’t answer your question. You state that you have some sort of converter (what brand) that comes out of your DVI port and does some sort of RGB to Y Pb Pr conversion, and this gives you a SD PAL signal that is crystal clear for your color correction. Please tell me what product you are using – is it a Matrox MXO ?

So now, you want to get a Magma chassis, stick a Decklink card in the Magma (will this actually work ? ), and monitor this way, so you can use the DVI port for a 24″ DVI monitor.

If I had to guess (since I don’t know what brand you are using now to feed your SD monitor), I would say YES the Blackmagic downconversion will be wonderful to feed your monitor. But your entire workflow is pretty unusual for someone working in HD.

Blackmagic makes many products to do this job better for you. You could take the HD output of a blackmagic card (like Decklink HD, since you are working in HD), and feed a Blackmagic HDLink ($445 US), and send this to any 24″ DVI monitor to see your HD (not SD) signal. You could use a Blackmagic Decklink HD Extreme to output the HD Y Pb Pr signal to feed an inexpensive Dell 2407WPF to see the HD signal. But if you want to use the JVC you own, this board will certainly downconvert for you to see the SD Y Pb Pr signal on your monitor, and the quality will be just fine (but you should tell me what brand of DVI to video converter you are currently using – if it’s the Matrox, it’s fine). This whole thing with the Magma chassis is pretty unusual, and like I said before – I won’t guarantee you that it will work.

Bob Zelin

[Miles Blow]

Hi guys
Just on the soft monitor issue…we shoot 3k with a digital slr (for animation) when we render a hd mjpeg at 1920×1080 we get a beautiful image out to our 24” dell through the multibridge extream but we get a lame arsed down conversion that is soft via s-video (sonypvm-14n6a).

If we render a sd (720×576) copy in AE of this same footage out to the sd monitor through the same s-video plugs we get an awsome picture, so that to me proves the analogue sd down conversion is soft…still ok for colour correction though just soft.

I guess the proper way to do it is by using a hd crt monitor with the hd sdi connection….that way letting the monitor do the conversion…let me know if im barking up the wrong tree with this theory?

[Dan Silber]

Thanks for your reply, Bob.

Yep, my workflow is unusual, let me explain: When I get hired as a freelance editor, I obviously enter a fully equipped editing suite with standard workflows.
BUT on the side I have my own projects which I edit in my “home editing suite”. I got rid of my G5 (and it’s slots for PCI cards) after switching to a fast MacBook Pro. (A worthy replacement, I compared them and posted the results on barefeats.com btw)

The reason for this unusual setup is, that for the next 2-3 years, these self-produced (pronounced “unpaid”) projects that I do will be delivered in SD or potentially DVCProHD, but acquired on HDV or DVCProHD. Anything with data rates beyond that is out of my budget.

Next on my agenda is editing over 40 hrs of documentary footage, that’s why I’ll get the Dell 2407 you mentioned.

So up to this point, I was able to use Apple’s downconversion in FCP to and use the RGB signal of the DVI port to hook up my JVC monitor. (Not YUV as I previously posted) The converter is called “RGB 190” by Extron Electronics: https://www.extron.com/product/product.aspx?id=rgb190&subtype=1

Any footage I edited (DV, HDV, DVCProHD) was crystal clear and played back smoothly on the SD monitor.

I see your point about getting the DeckLink HD, but the ExpressCard slot is only x1 PCIe, whereas the min. req. for the DeckLink is x4 lanes. I doubt HD-SDI output will be possible.

So the solution I am hoping that’ll work is:

1. A 24″ LCD connected via DVI as a secondary display:
This will allow plenty of workspace during normal editing (90 percent of the time), and also serve as a HD-Monitor if needed (using Apples “Digital Cinema Desktop RAW” function.

2. A Magma Chassis containing a “DeckLink SP”
The “DeckLink SP” should meet the x1 PCIe limits of the ExpressCard slot on my MacBook Pro.
I’ll use it for SD in/out and HD monitoring during normal editing on a SD monitor. (HD in/out will only be via FireWire). BUT: Only if the DeckLink donwnconversion is at least as good as Apple’s!

I have read many problems with “soft” downconverted images from the DeckLink cardon these forums. This has never been the case with the Apple built-in downconversion. What’s the deal here?

Thanks for your help!

[Chris Borjis]

[Creative Coward] “I have read many problems with “soft” downconverted images from the DeckLink cardon these forums. This has never been the case with the Apple built-in downconversion. What’s the deal here?”

The apple built in downconversion?
Do you mean when you set the monitor view lower than your
actual resolution? That looks just as bad as soft down conversion
on a black magic product.

I really wish they would enable hardware down conversion with 720p.
It looks fantastic with 1080i material

Why the hell won’t they give 720P the respect?

[Sean Oneil]

“Digital Cinema Desktop – RAW” outputs the video without scaling or deinterlacing. That’s nice and all, but the color is still wrong. It outputs the wrong colorspace and gamma levels because it is outputting a computer desktop signal, not a video signal..

A broadcast signal over DVI is YCrCb with a color range of 16-235. A computer monitor signal (like what you are using) is RGB with a color range of 0-255. Furthermore, the Quicktime engine changes the gamma level for playing back video on a computer monitor. Even with Digital Cinema Desktop, I’m pretty sure it still does this.

Your current “DVI output” is actually using the analog pins. So it’s really an analog RGBHV VGA output. The Extron box you are using doesn’t do anything to the color. It just takes the horizontal and vertical sync signals and adds them to the green signal to give you an RGsB which some broadcast monitors will support (like your JVC appearantly does).

This isn’t really my field of expertise, but I’m pretty sure that neither your current setup, nor your proposed future setup is suitable for color grading. I would recomend you check out the Matrox MXO and use that with the Dell monitor.

[Dan Silber]

Thanks for that, Sean.

A few thoughts:

1. Using FCP 6 I can monitor a downrezzed HDV via FireWire. If I connect that signal via a converter (ie camcorder, DV deck, AJA IO) to my broadcast monitor, will that show accurate colors?

2. I have read about an issue with the MXO and color on MBP’s ATI video interface, have you experienced that? -> https://www.dv.com/reviews/reviews_item.php?articleId=193104902

3. If I use the MXO on a laptop, would that mean I lose the option of connecting an external display (ie Dell 2407) for editing?

Thanks so much!

PS: For the sake of the complete picture, here’s my current setup:

I was aware that I was using the analog pins of the DVI signal, but I didn’t realize that there’s a different color space when using RGB from my DVI output vs. the RGB space within the video “world”.

I used a tool called “Display ConfigX” to send a clean PAL signal (720×576 @ 50Hz) from the MacBook Pro’s DVI via the Extron Box to the JVC monitor. (using Apples “output for Video” option). The monitor was then extensively calibrated using “SuperCal” ( https://www.bergdesign.com/supercal ). This was the basis on which I then calibrated the monitor the standard way with color bars.

[Sean Oneil]

[Creative Coward] “1. Using FCP 6 I can monitor a downrezzed HDV via FireWire. If I connect that signal via a converter (ie camcorder, DV deck, AJA IO) to my broadcast monitor, will that show accurate colors?

2. I have read about an issue with the MXO and color on MBP’s ATI video interface, have you experienced that? -> https://www.dv.com/reviews/reviews_item.php?articleId=193104902

3. If I use the MXO on a laptop, would that mean I lose the option of connecting an external display (ie Dell 2407) for editing?”

1. Yes, that will be a correct video output. It’s analog, but it should be fine, just may have to re-calibrate the monitor. However, doing this you are of coarse limited to HDV.

2. I haven’t used Color yet. I’m actually not a colorist (I mentioned this wasn’t my area of expertise). I also don’t have the X1900 card in my Mac Pro. Unrelated to this, I’ve read many nasty things about that card in a MP.

3. I’m not sure the specifics of how it works. I would read more about the product. You may be able to switch back and forth between desktop monitor and video monitor.

[Creative Coward] ”
I used a tool called “Display ConfigX” to send a clean PAL signal (720×576 @ 50Hz) from the MacBook Pro’s DVI via the Extron Box to the JVC monitor. (using Apples “output for Video” option). The monitor was then extensively calibrated using “SuperCal” ( https://www.bergdesign.com/supercal ). This was the basis on which I then calibrated the monitor the standard way with color bars.”

If you have the Display System Settings set for “video”, that may be ok. But it very well may not be either. You’d have to dig deep and really understand the code and how Quicktime processes things. You’d also have to scope everything to get a complete picture as to what’s going on and how the video output is being handled. There are a lot of behind-the-scenes stuff going on in OSX. The fact is, what you are doing is not the “proper” way to do it. So you may never know for sure whether or not it is giving you the equivalent of a true video output.

Sean