IO Express HDMI out not working properly

[Jorge Torrens]

Hi again Gary

[gary adcock]OK I took My Io Express and sent a 1920x 1080 ProResHQ file of the ASC’s StEM demo footage and set it up so that I could simultaneously view 3 different sources via Component to a Panasonic 17′ display, via HDMI to a HP Dreamcolor and using the HA5-3G converter (HDSDI- HDMI) from the HDSDIO output to my Sony Bravia XBR client monitor direct out of the IoExpress.

I do not see any difference between the signals, and my Tektronics scope confirms my visual inspection, but I do not have a HDLINK to test this on, but I am not seeing the differences you describe in the signal output with my tests.

Ok, here is where we are seeing something different, I’m sure you have the right setup to test it so I guess there is something wrong with mine. I only have access to a blackmagic ultrascope so no hdmi input to test it on.
You mention in your last post that you could access the video out for the aja in motion and after effects. Could it be that you are using a newer version of the drivers than the ones posted in aja’s website?

I understand the points you make about YUV and pfs but If I take YUV and pfs out of the ecuation by generating a gradient in nuke and monitoring from there, the wrong black levels persist.
Remember that I always have been able to access the different colorspaces in the Dreamcolor and this is only posible if you send a signal that is both RGB and true progressive.

Would you be so kind to check if your Dreamcolor firmware version is the same as mine TR:133 SL:063BL:167, and your IoExpress drivers are 1.0?

I am receiving very soon a Kona LHi and I have another dreamcolor where I can try both side by side.

Thanks again for your time and your answers, they are very thorough, both you and Jeremy are more than helpful.

I’m hopeful that with both your help I will be able to get to the bottom of my problem.

Jorge

[Jeremy Garchow]

If it is at all possible, it’d be nice if you could upload one second of an example image at full reoslution as a zip file. If a color chart/chroma du monde was shot, that’d be a nice example. I understand if you can’t.

I am finding the same results as Gary. Everything is looking ok here. I did have to setup the black level to get it the contrast/brightness correct. It is located in the image control menu. Using bars from FCP, I have a value of 125.

Jeremy

[Jorge Torrens]

Hi Jeremy I tried changing the black levels with a set of bars and with a value of 125, the same as yours and looks much better, the original one was 128, but I find odd that the monitor was calibrated using a probe and it worked fine before with a blackmagic card.

Anyway until I can test the signal with a waveform monitor, I believe it is close enough now to be usable.
I have created a new profile specific to the HDMI input that uses the colometry of the calibrated REC 709 colorspace with your suggested black levels.

Thanks a lot and best regards

Jorge

[Jeremy Garchow]

No worries and good luck with your project.

Jeremy

[Gary Adcock]

[Jorge Torrens] “I understand the points you make about YUV and pfs but If I take YUV and pfs out of the ecuation by generating a gradient in nuke and monitoring from there, the wrong black levels persist. “

First – The 1.0 Release version of the Io Express software does not support RGB V-out from any the animation sources you list. So there is some color conversion going on in your workflow that is not being accounted for.

Second- YUV and PsF are different things- one (YUV or Y’CrCb) is a Color Space- the other is a signal transport for progressive imagery as interlaced fields.

So lets start back at the beginning.
What do the Color Bars generated by Kona Control Panel via the device look like on your Display, not some questionable video but just something like 75% Bars?

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows for the Digitally Inclined
Chicago, IL

https://library.creativecow.net/articles/adcock_gary/AJAIOHD.php

[Jorge Torrens]

Hi Gary,

[gary adcock]First – The 1.0 Release version of the Io Express software does not support RGB V-out from any the animation sources you list. So there is some color conversion going on in your workflow that is not being accounted for.

I’m just using the HDMI output from to Aja to the HDMI input in the dreamcolor, so no extra conversions, and I can monitor in Nuke with no problems, but no in AE or Motion.

[gary adcock]Second- YUV and PsF are different things- one (YUV or Y’CrCb) is a Color Space- the other is a signal transport for progressive imagery as interlaced fields.

I clearly understand that, What I was meaning is that using nuke and a gradient generated in nuke it would be by definition a progressive rgb image, so it would not be any extra conversion from yub to rgb or psf to true progressive, and would be one less thing to consider.

[gary adcock]So lets start back at the beginning.
What do the Color Bars generated by Kona Control Panel via the device look like on your Display, not some questionable video but just something like 75% Bars?

Exactly the same problem, the black level is to high. If I adjust the black level in the monitor as per Jeremy’s suggestion I can get an image that looks fine, but it kind of defeats the porpouse of having a calibrated monitor, doesn’t it?

For the time being, I hope to have access this week to a hdmi to sdi converter to check the signal in a waveform monitor, this solution is ok, but I’m not very comfortable with it

Thanks again for your help

Jorge

[Gary Adcock]

[Jorge Torrens] “[gary adcock]First – The 1.0 Release version of the Io Express software does not support RGB V-out from any the animation sources you list. So there is some color conversion going on in your workflow that is not being accounted for….

I clearly understand that, What I was meaning is that using nuke and a gradient generated in nuke it would be by definition a progressive rgb image, so it would not be any extra conversion from yub to rgb or psf to true progressive, and would be one less thing to consider.”

OK – the IoX does not support RGB video out- so something is doing the conversion from your Nuke file to YUV- it is NOT the hardware.

[Jorge Torrens] “Exactly the same problem, the black level is to high. If I adjust the black level in the monitor as per Jeremy’s suggestion I can get an image that looks fine, but it kind of defeats the porpouse of having a calibrated monitor, doesn’t it? “

Isn’t that what calibrating a monitor is??- adjusting it so that the viewing space is a close to correct as possible? Correct calibration of BroadcastVideo monitors is done using the “blue only settings” while viewing 75% SMPTE Color bars.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows for the Digitally Inclined
Chicago, IL

https://library.creativecow.net/articles/adcock_gary/AJAIOHD.php

[Jeremy Garchow]

No, it doesn’t defeat the purpose in my opinion. Basically, the Dreamcolor works on full RGB. You do the calibration and the colors are matched and then the colors get mapped to the different specifications, REC709 being one of them. This is similar to a LUT. Now, as far as what is traditionally known as brightness on a CRT, you have to calibrate the monitor to that relative to your room. The ‘black level’ as it’s known in the monitor is akin to brightness on a CRT. Part of calibrating the monitor is to have you adjust the black level. That doesn’t have anything to do with the probe. The probe gets you the accurate RGB colors and then maps that to the appropriate color space. You can then use the pluge on SMPTE bars to change the black level of the monitor, and then you can turn up or down the overall brightness of the monitor without effecting color or contast, it just changes intensity. It is ultra cool if you ask me. Sure, it might have be a monitor from a computer company, but it is unlike any flat panel monitor I have seen. The LED backlighting and 10 bit panel are very nice looking, especially when you factor in the price.

Jeremy

[Jorge Torrens]

Hi Gary

[gary adcock]OK – the IoX does not support RGB video out- so something is doing the conversion from your Nuke file to YUV- it is NOT the hardware.

Good to know, then it must be nuke the one doing the conversion to YUV, but then how it is posible that the Dreamcolor sees the image as RGB, otherwise it would not allow to select a colorspace?

[gary adcock]Isn’t that what calibrating a monitor is??- adjusting it so that the viewing space is a close to correct as possible? Correct calibration of BroadcastVideo monitors is done using the “blue only settings” while viewing 75% SMPTE Color bars.

I meant having the monitor calibrated by the probe as opose to manually calibrating using bars and blue only settings. But as Jeremy points out in his last post, it is posible to have the colorimetry of the monitor calibrated by the probe and then modify the black levels in the dreamcolor without modifing the relationship between the colors or the contrast.

I guess what made me uncomfortable was the fact that if I had the monitor calibrated before and the different outputs from the IoExpress as well as the ones from the blackmagic should be outputting the same levels, then why should I have to adjust the black level of the monitor when changing from one output to another.

Sorry again Gary for the trouble, this threat is getting very long and I’m feeling guilty of wasting your time and Jeremy’s in a problem that is quite particular to my workflow.

Jorge

[Jeremy Garchow]

[Jorge Torrens] “this threat is getting very long and I’m feeling guilty of wasting your time and Jeremy’s in a problem that is quite particular to my workflow. “

Not at all, Jorge. The Dreamcolor represents a different workflow and thinking behind a traditional CRT calibration. It is something that should be discussed, do not feel guilty and if you are enabling this kind of workflow, there are many many more people out there who are doing this workflow or at least thinking about doing this type of workflow and they will benefit from this thread.

[Jorge Torrens] “but then how it is posible that the Dreamcolor sees the image as RGB, otherwise it would not allow to select a colorspace?”

The ioExpress is outputting RGB.

[Jorge Torrens] “I guess what made me uncomfortable was the fact that if I had the monitor calibrated before and the different outputs from the IoExpress as well as the ones from the blackmagic should be outputting the same levels, “

That’s a rather broad assumption. The purpose of the calibration is to calibrate the material to your output. Also, DVI is 8 bit, and HDMI 1.3 is 10bit. The HDP2 and ioExpress can both output true 10bit HDMI 1.3a signals, not sure about the Blackmagic. I don’t think it offers this capability. The HDP2 does this over a physical DVI port connection, but all you need is a DVI to HDMI cable and you are sending an HDMI 1.3a signal. It’s pretty cool.

Jeremy