[vcf-midatlantic] Any MIDI enthusiasts around?

[Ethan O'Toole]

This is a bit of my world. You man know a lot of this.

Midi "DJ" style controllers usually use note on/off for LED feedback on 
them (Akai APC-20. 40, maybe Novation Launchpad?) Those are often 2 color 
and off, though. Controllers with RGB buttons for feedback will often go 
Sysex.

You could do MIDI and use the controller change messages. Don't remember 
if 0 to 127 or 0 to 255 but you get 127 of them per midi channel, 16 midi 
channels on a standard old school cable.

Midi and DMX were never really built to do high pixel count RGB or in your 
case RGBW strips, but people use them!

Note, stuff with SPI -- if you are doing things like rapid updates if I 
recall things like Arduino weren't strong enough CPU wise to handle doing 
the constant refresh of the pixels and also taking in Ethernet frames (or 
maybe midi data.) It will cause glitching. Stuff like the Teensy does 
fine.  This is for pixels that do not have a clock line and require a 
pretty accurate timing to shift in all the RGB or RGBW or RGBA data.

In the pro world it is DMX512. You can cheat and use 3 pin XLR, it's rare 
to see actual 5 pin connectors on hardware (at least the pro fixtures I 
have seen. But the controllers usually have the 5 pin plugs to annoy you 
so you have to use those 5 to 3 adapters. Cheap RS485 line drivers get you 
DMX512 in and out, and there is code on Arduino and others to speak this.

Soooo in the modern world, most high count pixel systems are using Artnet 
or sACN 1.31 which is DMX512 data encapsulated on ethernet. The Christmas 
light systems do this, software like Madrix which is often used for those 
volumetric LED displays in clubs (check out their demo reels, cool stuff.) 
Modern lighting desks speak this. It's still very odd because they are 
breaking down MASSIVE arrays of LEDs into these 171 R+G+B values stuffed 
into DMX universes. Which usually all have to be mapped and placed in 
space, then they logically dump a graphic file or video file on top of it 
all and shoot that data down the wire.

For VCFE I was using a Pi with Open Show Control running on Pi3/Linux that 
allows going sACN 1.31/Artnet from network over to physical DMX512 and a 
proprietary Phillips protocol for Color Kinetics stuff alled KiNet. It's a 
neat toolkit for protocol conversion.

Existing solutions for ArtNet/sACN to pixels ... Alphapix from HolidayCoro 
is what I use, at about $200 for 16 LED universes and 2 RS485 universes 
before expansion boards are added. There is a few Chinese things on eBay, 
and there are some hats for the Pi that the Christmas light people use.

A small cheap board that did sACN/Artnet via Ethernet to LED pixels would 
possibly sell, especially something small and cheap so maybe they can be 
more distributed? People like HolidayCoro sell some extender system but 
it's about $100-$200 for a pretty low count. They are buffering the SPI 
signal and driving it differential I think. Would make more sense to just 
run ethernet to everything.

There are these other Chinese controllers that are ~$8-$20 called WLED or 
something that run on ESP32/8266 type ICs that have phone apps that talk 
bluetooth or wifi and it can push pixels. They are cute, neat, but it's a 
hassle connecting to them and controlling them on a whim. It might open 
the door for hardware that can be repurposed. There is an open source 
project that replaces the software in them, but I don't remember the 
details. I will be using it on my vehicle though, I plan to do RGB strips 
underneath it because neon is cool. Makes vehicle look like a spaceship.

It would probably be easy enough to support both midi via an optoisolator 
or whatever or the other protocols. Depends on how you want to talk to it 
with old computer? ISA card!


Madrix Eye candy:
https://www.youtube.com/watch?v=dKmLTRWWKCc
(laser safety zones? what?)

https://www.youtube.com/watch?v=c4pyFgy0sZE
(LEDs and Kinetics!!! Volumetric!)

xLights software (was called Nutcracker):
https://www.youtube.com/watch?v=bXlDqw2BFA0&t=38s
Note - those aren't spotlights. There is just so many LED pixel arrays 
attached to the house it looks like one? 171 LEDs a universe, and there 
are 3 story high video screens made in this fashion. Pity the soul that 
configured the software!


 		- Ethan



On Sun, 13 Mar 2022, RETRO Innovations via vcf-midatlantic wrote:

> I am looking to control some RGBW leds (maybe SPI-based strips, maybe 
> individual high power RGBW LEDs, not sure yet) with some of my classic 
> computers.
>
> That's pretty easy, no concerns there.  Lots of arduino projects or I can 
> just add in a 6522/6821/etc.
>
> But, I thought, instead of just making a hobby project, I should try to 
> design something that would work with classic systems *AND* current gear, and 
> not be so platform dependent.
>
> MIDI came to mind, both because the cost to interface is pretty low, cables 
> are cheap, and MIDI is very well supported.
>
> Where I am struggling is getting a handle on how to map the ability to set an 
> individual LED color in a strip of say 20 or 60 to the MIDI protocol without 
> just punting and using SysEx msgs. And, I might have a bunch of these strips 
> (more than 16 perhaps, though my initial project only needs 10-12.
>
> I am also aware of DMX lighting and MIDI->DMX converters.  DMX XLR-5 cabling 
> is a bit pricier than MIDI 5 pin DIN (though the RS485 protocol seems simple 
> enough), so I thought maybe I should just emulate a MIDI->DMX->LEDs in my 
> design.
>
> Anyone familiar with MIDI-controlled lighting and how it's mapped to MIDI 
> messages?
>
> Jim
>
> -- 
> RETRO Innovations, Contemporary Gear for Classic Systems
> www.go4retro.com
> store.go4retro.com
>
>