NOOB NEEDS HELP: Digital To Analog To Digital

Hi there! I’m new to this video synthesis stuff and could use some help figuring out exactly all that I need to do what I want to do.

I pretty much want to take HD digital files from my computer, convert them to analog to run through RGB effects, and then convert them back to digital, while retaining the quality as best as possible. So that I could edit the effects video into the original without worrying about quality/size changes.

I just need to know what cables and devices are necessary to smoothly do this.

Right now I have hdmi coming out of my computer, if I ran that into a Decimator HX (hdmi in), converted to SDI (SDI out), then used BNC to RCA cables to run into the analog effects, then run that output through a Black Magic analog to SDI converter (RCA in, BNC out) run back through the Decimator (SDI in, HDMI out) back into a capture device would that work?

Any tips and steps in between would be much appreciated. This stuff has been stressing me out!

Happy to be a part of the community, LZX and video synthesis is awesome.

Quite a few people use this.

Although if you want to computer > LZX and then back LZX > computer… you would need two of these. Blackmagic makes a few other devices that are duplex (run both ways simultaneously) but you would need to pony up some more cash as those devices are more expensive.

There are also other ways of doing this with some cheap converters etc. but I can not speak to that.

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I don’t think there’s such a thing as an “SDI to RGB cable” - it would need to be another converter. Then with standard RGB video you still have to convert it to LZX euro standards (i.e. 0 to 1V and eurorack impedences rather than 75 ohms). So it might be more involved than what you’re suggesting.

Syntonie’s YUV to euro RGB converter (VU003, only available for DIY I believe) might be a good option, if you can find a direct HDMI/DVI-to-YUV downscaler to use with it. You’ll also want something to extract sync from Y, for aligning your LZX gear. I really only know the DIY product ranges so others will have to help out with your options there - Chromagnon maybe? (I use a Cadet I)

However, most analogue modular video gear is going to struggle to retain HD image quality, because it’s not really designed for it - it’s much harder to build analogue circuits that handle the higher data rates that HD uses :frowning:

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I meant BNC to RCA, those cables do exist. But it sounds like I’m going to need a converter for both ends. I understand the analog gear is going to have trouble retaining quality, that’s why I want to be able to match it up and edit it with the original file.

What would be the result/downsides of using 2 converters like the BM Intensity shuttle That Desert Museum recommended?

Also I have a Decimator Hx, would there be a problem using that as one of the converters?

Welcome aboard @Kennethfrosty2!

So you should spend a bit of time on this page:

Now, that’ll likely freak you out a bit more as there’s like A MILLION converters for all sorts of different jobs. It’s easy to get lost in the weeds comparing and contrasting what the different models do. The two I’d recommend exploring are the:

Mini Converter SDI to Analog - $195
Mini Converter Analog to SDI - $195

These would both enhance your use cases with your MD-HX.

Like others have already mentioned, the Intensity Shuttle is hard to beat for what you want to do in terms of cost and abilities.

So, let me run down what I think you’re trying to do and you can correct me if I’m wrong.

You have HDMI coming out of your computer which you want to convert to analog to run through RGB effects. Lets unpack that a bit. HDMI is a digital signal and likely outputting a 1080p signal.

Now a question. Which LZX device are your trying to get this signal into? I’m guessing NOT Memory Palace due to your interest in getting the signal into analog. I ask because MP can take an HDMI input.

If it’s Visual Cortex, it accepts NTSCi @ 720x480i (I’m only addressing NTSC but PAL options exist). So your HDMI 1080p coming out of the computer needs to get to 480i along the way to LZX. This thread has useful details for you:

Additionally, it really matters if you are intending to enter LZX as a composite (single RCA) or component (three RCA YPbPr ). As you repeatedly mention a desire to retain quality through the system, I’d guess you’re opting for component YPbPr input.

If so your HDMI signal needs to be downscaled and converted for entry into LZX. Your MD-HX can downscale the HDMI but cannot convert to component. It can convert to SDI and an SDI to RCA cable could carry composite signal to LZX. But that is grayscale only on one channel. To get the maximum analog image quality the signal needs to be converted to component.

If you choose to use your MD-HX to convert HDMI to SDI, then the next step could be the BMD Mini Converter SDI to Analog. From there your signal would be ready for entry into LZX as YPbPr component.

Early on, a confusing aspect of all of this for me is the fact that SDI is a signal and BNC is a connector type. They are not the same thing though they often work together. Signals work independently of connector types. In LZX the most commonly used connectors for input/output are RCA and S-Video.

So that BMD converter has BNC for all of it’s input/output. Your MD-HX converted the HDMI to SDI and that SDI signal is output on a BNC connector. So the output from the MD-HX is carrying all the signal information it needs to work in YPbPr but needs a converter to do it. You’d enter in as SDI from MD-HX into BMD Mini Converter SDI to Analog, and out from BMD’s three BNC connectors via three BNC/RCA cables into LZX YPbPr in.

A word about BNC/RCA connectors and cables. There’s countless ways to roll these and they all boil down to preference and how much you’re willing to spend. A CHEAP RCA cable can have CHEAP RCA to BNC adapters slapped on any end of the cable. In fact with two adapters you can create a BNC cable from an RCA cable. And vice versa. That said, noise in the system is more noticeable in video, and cheap adapters can introduce noise if they don’t connect firmly. High quality cables and adapters exist, but that is something for another discussion as opinions can get heated when talking about such matters.

Ok. You’ve gotten the signal into the LZX world, you’ve done your processing, and you’re ready to capture back to the computer. Now you need to reverse the steps and account for scaling, converting, and connecting. You can use the same type of tools to do this assuming the computer you have has more than one HDMI port. You’d come out of LZX into Mini Converter Analog to SDI, and BMD SDI out into MD-HX, then MD-HX HDMI out back into the computer.

My Macs do not have more than one HDMI port, so this flow doesn’t work for me. This is why I’ve gone with dual BMD Intensity Thunderbolt Shuttles for my flow. Here are some useful threads on that topic:

Notes on Intensity Shuttles. In my experience with Thunderbolt and Macs they are rock solid. Others have had problems which seem to be experienced when trying to use TB with Windows PCs or when using USB3 Shuttles with Macs. I do not have first hand experience with those issues but have read discussions with frustrated people trying to get things to work.

Pros of Shuttles:

  • HDMI/S-Video/Compopnent/Composite input and output (BUT ONLY ONE DIRECTION AT A TIME!!) So you’d need two for concurrent input/output.
  • Affordable. Even more so second hand because some people get them and rage quit at markdown pricing.
  • All-in-one. You can do what you’re trying to do with two units. The flows described above need at least four units.
  • Supports 10-bit color depth over component output. See this thread for why that might be important to you if highest quality is your primary concern:

Cons of Shuttles:

  • TB cables can be pricy.
  • BMD software (to control input/output settings) can be fiddly to dial in to your exact needs.
  • Not great at upscaling or downscaling. (That’s where your MD-HX really shines!)

Whew! Sorry to go so deep but I know how overwhelmed I was when I got started as there are SO. MANY. MOVING. PARTS!!!

Stay strong, keep digging, and cut yourself a lot of slack as your learning. You might lose a bit of money trying different things out, but usually you can sell and try again without taking much of a loss.

Last words. If you have any friends into this, go try their setups to see what you like and don’t like. I’ve learned SO MUCH over the years through the generosity of others willing to talk shop and showing me their setups. C19 makes that a bit more challenging at the moment.

Good luck and enjoy this part. Its a colossal PITA but you’ll get it and feel like a champ when you do! :slight_smile:


@337is how do I nominate you for poster of the day/week? :slight_smile: This is an awesome, really helpful post.


Cheers @aladan! :slight_smile:

Thank you so much. I’m gonna let all of this soak in and will keep you all posted on my journey! :metal: