Vmix Video mixer controller

[ittaidv]

Hi all,

I'm new to electronics, but recently i got interested into this domain because I don't have enough money 

Background

Let me explain a bit of my background first: I'm a video specialist in the domain of live productions. Together with my friends I started a production company called Slash9.tv.

With Slash9.tv we capture and stream musical events. We do this by using a computer, some capture cards and a software called Vmix.

Vmix allows for unlimited video sources to be mixed together, combined with graphics, videos, audio, .. It's the cheapest way to get into serious live video production.

Problem

In the beginning our setup was pretty modest: 3 gopro's and a handycam, routed via capture cards and firewire into the computer. The last few months we got more serious into this and bought some extra camera's to beef up our productions. Soon we will step up the game even further and buy a monster dual pc setup that will allow us to mix up to 20 camera's at once using our beloved Vmix software.

That leads me to the main problem that comes with computer based swithing and the reason I got interested in electronics: CONTROL.

Controlling 4 camera's with mouse and keyboard is no problem: we just mapped each camera to a numpad key: numpad 1 for camera 1, numpad 2 for cam2, etc..

Controlling 20 camera's over a keyboard is a different leage: there are not even enough numpad keys

Research

Looking at commercially available controllers I didn't found anything that really suited us: either the controllers are too small, not really suited for video (lacking T-Bar), or way too expensive for what they deliver.

Some people sell some neat DIY but expensive DIY stuff, and that got me thinking about building it myself and saving some bucks.

For example this guy is selling something that is close to what I want: http://www.h3j.com/index.php/products/c-series-consoles/c200

If you look close at what he builds, it's just a commercialy available T-Bar controller with hall effect, some illuminated buttons, a arduino pcb, an lcd and some rotaries in a nice enclosure. Total cost 600 bucks?

Solution

That's why I started thinking to build my own, custom kickass controller.

What I want to build is something that looks like this one: http://www.bhphotovideo.com/bnh/controller/home?O=&sku=1004641&gclid=CKuL1uyz6cICFUbLtAodbRsA-Q&Q=&is=REG&A=details

72 illuminated buttons
1 T-Bar
5 rotaries
Console enclosure + lasercut front
HID pcb's

I found most of the parts online already:

72 Buttons: 33*33mm lighted button Illuminated Push Button with microswitch (72 dollar)
http://www.aliexpress.com/item/12-pcs-of-square-33-33mm-lighted-button-Illuminated-Push-Button-with-microswitch-for-arcade-game/1135797839.html

1 T-Bar: TBF-PO (168 dollar)
http://www.digikey.com/product-detail/en/TBF-PO/679-2284-ND/2063275

5 Rotary knobs (potentiometers) (8 euro)
https://www.conrad.nl/nl/potentiometer-service-gmbh-draaipotmeter-alpha-pot-16-9310-mono-lineair-500-k-02-w-450042.html

1 Enclosure: Hammond Electronics 1456WK4BKBU (70 euro)
https://www.conrad.nl/nl/hammond-electronics-1456wk4bkbu-consolebehuizing-265-x-508-x-107-aluminium-blauw-zwart-459010.html

Lasercutting console: 75 euro

2 PCB's:

1  KE72-T (120 dollar)
http://www.hagstromelectronics.com/products/ke72detail.html
1 I-PAC ULTIMATE I/O (99 dollar)
http://www.ultimarc.com/ipacuio.html

All together (in euro with estimated shipping and taxes included): 640 euro

Question

Since it's a lot of money to buy and ship these things to my house, I first want to be sure that everything would work as I imagine now.

I was thinking to connect the push buttons to the KE72-T  board. This board can connect up to 72 buttons and connect to my pc over the ps/2 port.

The leds of the buttons I wanted to connect to the  I-PAC ULTIMATE I/O, which supports 96 LED's.

The rotaties and the T-Bar i wanted to connect to the  I-PAC ULTIMATE I/O as well.

When everything would come into the computer, I thought i should find a way to program everything so that it works like this:

3 rows of 20 buttons: when 1 button from the row is pushed, the light of this button shines. When another button of the same row is pushed it starts shining, while the previous button stops shining.
12 buttons: when pressed they shine, when pressed again they stop shining.

Is what I want possible with this hardware? Or should I look at something different?

Thanks!

IttaiDV

[PL1]

Welcome aboard, Ittaidv.   

Sounds like an interesting and rather challenging build.

Several things to consider:

* The buttons you linked are momentary and aren't latching/ganged (ganged = push one, the others in the row pop up) so the LED animation will need to be controlled by software/firmware.

* What software will you use to handle the LED animation? (LED Blinky?)

You may need to write custom code to handle the LED lighting behavior you describe with the rows of buttons.

If you're doing that, it's not that much more effort to add the HID keyboard code as well.

Disclaimer: I'm not familiar with the number of inputs/outputs on the various Arduino boards.

Maybe one Arduino per 20-button row (20 button inputs, 20 LED outputs) and one for the 12-button row if you don't have enough leftover inputs on the others.

* You should be able to use DPST (double-pole, single-throw) or DPDT (double-pole, double-throw) latching illuminated buttons for the 12 press-on/press-off buttons. (No need for software animation of the LEDs this way.) Check Digikey, Mouser or Allied Electronics for options.

* Even if you don't "roll your own" LED controller/HID keyboard encoder, the Hagstrom encoder is really expensive and unnecessary.  Use the unused inputs on the Ultimate I/O and another less expensive encoder like an I-Pac or a KADE. (windows can handle multiple keyboard encoders)

* The pots you linked are linear.  Shouldn't they be log for audio?

* The T-handle you linked is pretty expensive. LMK if you want an almost-complete parts list for a FAR less expensive DIY version.

* A 4-axis joystick (X, Y, twist handle, and pushbutton) like the one on the controller you linked to is available here at Amazon.


Scott

[SavannahLion]

Maybe one Arduino per 20-button row (20 button inputs, 20 LED outputs) and one for the 12-button row if you don't have enough leftover inputs on the others.

He probably doesn't want to spin his own code though. Using something like an Arduino means he has to be aware that most Arduino's use a serial to USB bridge which will be near useless for his application. Select one that is native USB, such as the Atmega32U4 (which isn't specific to the Arduino anyways).

The 32U4 has 26 I/O with 12 ADC channels (they are multiplexed). Using a single USB AVR, he'll be forced to use some form of multiplexing and charlieplexing to get it all on one controller, but it can be done.

Jump up to a 32 bit controller, like the ARM and he'll get far more wiggle room. PJRC built an interesting I/O board using his Teensy 3.0 taking full advantage of multiplexing cramming an obscene number of inputs on one joystick HID.

Log vs Linear is irrelevant if he spins his own code. You can tweak the curve one way or the other programmatically. The analog resolution on the 32U4 is limited, IIRC, to 10 bits anyways.

Just some thoughts.

[ittaidv]

Welcome aboard, Ittaidv.   

Sounds like an interesting and rather challenging build.

Several things to consider:

* The buttons you linked are momentary and aren't latching/ganged (ganged = push one, the others in the row pop up) so the LED animation will need to be controlled by software/firmware.

* What software will you use to handle the LED animation? (LED Blinky?)

You may need to write custom code to handle the LED lighting behavior you describe with the rows of buttons.

If you're doing that, it's not that much more effort to add the HID keyboard code as well.

Disclaimer: I'm not familiar with the number of inputs/outputs on the various Arduino boards.

Maybe one Arduino per 20-button row (20 button inputs, 20 LED outputs) and one for the 12-button row if you don't have enough leftover inputs on the others.

* You should be able to use DPST (double-pole, single-throw) or DPDT (double-pole, double-throw) latching illuminated buttons for the 12 press-on/press-off buttons. (No need for software animation of the LEDs this way.) Check Digikey, Mouser or Allied Electronics for options.

* Even if you don't "roll your own" LED controller/HID keyboard encoder, the Hagstrom encoder is really expensive and unnecessary.  Use the unused inputs on the Ultimate I/O and another less expensive encoder like an I-Pac or a KADE. (windows can handle multiple keyboard encoders)

* The pots you linked are linear.  Shouldn't they be log for audio?

* The T-handle you linked is pretty expensive. LMK if you want an almost-complete parts list for a FAR less expensive DIY version.

* A 4-axis joystick (X, Y, twist handle, and pushbutton) like the one on the controller you linked to is available here at Amazon.


Scott

Wow Scott, thanks for the reply, this is already helping me forward a lot!!

But I have some additional questions

- I was indeed thinking to control the leds with Leds with Led Blinky, but now when i researched this software, i saw that it's rather limited. Is there other software that works with a GUI to control the leds of the I-PAC?

-If there is no GUI to control them, is there a place where i can find example code to control these LED's?

- If I use multiple Keyboard controllers over usb, would it be a solution to use a USB hub inside the machine, so I can have a single cable running to the pc, or would this give me power problems?

- For the pots: I would use them to control software functions, so that's why i picked linear ones, correct me if I'm wrong.

- The T-handle is indeed quite expensive, i'm now looking at them because they make the project less complicated. I found a really nice DIY solution on the ATEM forums, but i think this would be something for a next project . I found a lot of used video mixers on ebay, i might buy one for under 100 euro and take some pieces out of it to re use in my project.

-Super nice you found the 4-axis joystick, I'm just not sure how I would use it in my workflow right now, since the Vmix API only allows control of the basic functions.

IttaiDV

[ittaidv]

Maybe one Arduino per 20-button row (20 button inputs, 20 LED outputs) and one for the 12-button row if you don't have enough leftover inputs on the others.

He probably doesn't want to spin his own code though. Using something like an Arduino means he has to be aware that most Arduino's use a serial to USB bridge which will be near useless for his application. Select one that is native USB, such as the Atmega32U4 (which isn't specific to the Arduino anyways).

The 32U4 has 26 I/O with 12 ADC channels (they are multiplexed). Using a single USB AVR, he'll be forced to use some form of multiplexing and charlieplexing to get it all on one controller, but it can be done.

Jump up to a 32 bit controller, like the ARM and he'll get far more wiggle room. PJRC built an interesting I/O board using his Teensy 3.0 taking full advantage of multiplexing cramming an obscene number of inputs on one joystick HID.

Log vs Linear is irrelevant if he spins his own code. You can tweak the curve one way or the other programmatically. The analog resolution on the 32U4 is limited, IIRC, to 10 bits anyways.

Just some thoughts.

Indeed I don't want to write too much code. I have a basic Javascript understanding, but there it stops. I'm able to learn fast though, so If needed and with some example code I would probably finf my way.

I thought it would be the easiest to work with HID compliant controllers, since that would enable me to translate the button and analog controls into keystrokes. Since the Vmix API accepts GUIDS or key commands, this would be the easiest way to work it out.

http://www.vmixhd.com/help14/

IttaiDV

[PL1]

- I was indeed thinking to control the leds with Leds with Led Blinky, but now when i researched this software, i saw that it's rather limited. Is there other software that works with a GUI to control the leds of the I-PAC?

I'll let those with LED animation experience chime in on this since I usually just wire LEDs for single-color always-on.

-If there is no GUI to control them, is there a place where i can find example code to control these LED's?

It would depend on what programming language you're working in.
I'm sure there are some good sources, but I have no suggestions at this time.   

Have you found any controller projects at the vMix forums that you can use as a foundation for your code?

- If I use multiple Keyboard controllers over usb, would it be a solution to use a USB hub inside the machine, so I can have a single cable running to the pc, or would this give me power problems?

As long as each AVR draws less than 100mA total you won't have any problems using an unpowered 4-port hub according to the USB specification.

Most LEDs are designed to draw about 20mA.

The "12 button" board could draw way more than 100 mA unless you do these two things:

  1.  Use 12v LEDs powered by 5v.  Paradise Arcade Shop 12v LEDs powered by 5v only draw 5.83 mA each when you add an extra resistor like R2 here.

  2.  Move 1 or 2 of the 12 to each of the other boards to spread out the current draw.  If there's room for 4 on the other boards, you can remove the "12 button" board altogether.   

You may want to use a Neutrik NAUSBW-B feed-thru for a nice finished look on the outside of the enclosure.   

- For the pots: I would use them to control software functions, so that's why i picked linear ones, correct me if I'm wrong.

That was just the old-school analog part of my brain asking.   

As long as they work for your application and are high enough quality, you should be fine.

Haven't looked at the data sheet on the pots, but you may want to verify that the pots are long-life versions.

The cheap Radio Shack pots don't last very long but Honeywell pots like this one from the RV4 series are long-lasting and not too expensive.   


Scott

[ittaidv]

Thanks again for the helpful suggestions Scott!

I just checked out the animation editor that comes with LED Blinky, it looks very complicated and I didn't have time yet to check it out completely, but wouldn't this get the job done?

I'm a regular at the Vmix fora, helping other people out with their computer building projects. It's not a huge community and there are no code examples available at this moment. This is not a huge problem though, since the API looks not too complicated at first sight.

BTW, today i discovered some great deals on ebay on used old videomixers. I can get a complete videomixer with 2 T-Bars for 50 dollars, might order one and take it apart to re-use some buttons, pots and T-bars. Would that be a good idea?

[PL1]

I just checked out the animation editor that comes with LED Blinky, it looks very complicated and I didn't have time yet to check it out completely, but wouldn't this get the job done?

Like I said, I'm no expert, but hopefully Arzoo (the author) or someone who may have done something similar with LED Blinky will reply.

BTW, today i discovered some great deals on ebay on used old videomixers. I can get a complete videomixer with 2 T-Bars for 50 dollars, might order one and take it apart to re-use some buttons, pots and T-bars. Would that be a good idea?

Sounds like it might be worth taking a chance.   


Scott

[SavannahLion]

I would take one apart and repurpose the guts. Only gotcha i can think of is if the pots or sliders need work.

[arzoo]

LEDBlinky could be used to run animations but it has very limited functionality when responding to keyboard events. A custom control app would have to detect the keyboard events and send manual commands to LEDBlinky. Or the control app could just send the commands directly to the Ultimate I/O via its interface library.

[ittaidv]

Anyone who knows example code that is available on the internet?