Loopback. What is it for?

[prophy17]

Hi. What can you say about Loopback in the qlc+ projects? What is it for? Any practice with it can anybody describe. I think - it should be clear for every user and not a "secret magic")). Are you agree with me or I am wrong?

[prophy17]

There are many video tutorials for simple scenes and not one detailed for the Loopback function. I think it's not right.

[kenact]

There is a description of the Loopback in the manual, with an example.

My most frequent use is to fade music. I typically create a Chase for my pre show music, then use another Chase to set up the fade out time, using 2 scenes. On my VC I add a button to start the pre show Chase, a Slider linked to the Chase and the Loopback, and a button to run the fade out Chase.

You can find examples of Loopback usage by searching the forum.

[prophy17]

Thank you for your answer. It's interesting, but not clear for me. Would you mind download any example?

[prophy17]

And first of all I want to say, that excuse me, but I don't understand absolutely - why one widget can't be connected with another like this widget can be connected with a function. Why is so hard to make connection of both widgets of Virtual console? Instead of this user should create new: Loopback universe, dimmers on it, scenes with these dimmers, profile with some channels only for connecting some widgets between each other. Maybe I am a funny man))? But I have such question in my mind. Excuse me one more time for my lack of understanding.

[prophy17]

For example. Why a button on Virtual console can activate a chaser, but not a cue list? It needs The Loopback Magic. I don't understand.

[GGGss]

Vlad,
Remote controls or loopbacks are an industry standard.
If you know something about microcontrollers or PLC's, you'd know that there is a sequence to follow.
* read inputs
* do the user-programmable logic
* set the outputs
Internally, this logic is present in the core of QLC+ - the backend so to say.

The reason why you can't connect one function to the other on the VC, is because of this programmable logic explained above. What you do on VC influences the output side of the logic. And because this can't be estimated when inputs are read, we need a loopback (or remote control on big desks) for this to happen.
* read inputs
* do the user-programmable logic
* add the Loopback-magic
* set the outputs + loopbacks
* read inputs + loopbacks
* do the user-programmable logic
* set the outputs + loopbacks

Now you can argue with: "ok, but why can't this functionality be included in the core?"
Answer: Loopbacks are soo strong and powerful, as a programmer, you can not predict what users will think of as being needed for their projects and the influence it has on the output side of the core. KISS principle: Keep It Simple Stupid (or Stupid Simple) - give the power to the creative minds who will misuse the Loopback-Magic to their will.

The same goes with the scripts... but that is another topic.
Scripts in QLC+ are underdeveloped IMHO... v5 is to the rescue here.

In comparison to the big desks, GrandMA stands up front. You have macros - very powerful and really nice to have. Macros reside inside the user-programmable logic in the scheme above.
For the extreme power users, there is LUA - a computer language where you actually can influence the core. The block of 'user-programmable-logic' inside the core.
Can you see where I'm pointing at? Mayhem if you f**kup. And completely impossible to debug for sure.

So for now - and for God's safety - stick with the LoopBack-Magic.
Amen!

[MichelSliepenbeek]

Vlad should first concentrate on understanding the basic logic of QLC.

On the Function Tab you create Scenes and Chases (and more complex stuff, like Sequences, RGB matrices and EFX's).
On the Virtual Console Tab you can use a number of Widgets to control those Functions: a Slider to set a level, a Button to start a scene, a Cue List to control a Chaser, XY-pads to control Pan and Tilt, a Speed Dial to control the Timing of changes.

Why a button on Virtual console can activate a chaser, but not a cue list?

The reasoning in this example doesn't make sense. If you start your example with the wrong arguments (if you use a Widget that does not fit the Function, like starting a Chaser with a Button), you just don't get the results you expect.

In QLC the Cue List is the widget that is specifically designed to Activate a Chaser (not a Button).
The Cue List already provides Buttons for Play, Pause, Stop, Next and Previous. What does Vlad want his Button to do?

[prophy17]

Thanks you very much for your answer, Dear Michel. I have felt like a schoolboy))) during reading your message. Maybe I have been wrong with the button for a Cue list activation. But in your file of qlc+ project with Loopback from another thread there is the button, which create the pages of the multipage frame, for example. There are buttons for pages in this widget (multipage frame) too, like a cue list, but you have done the special button for it with Loopback function. By the way, as I have written before, maybe it should be good to download to this thread your example with Loopback. Your files with the Loopback examples helped me very much. Thanks one more time for them.

[prophy17]

And one more question , Dear Michel. You have said, that v.5 is the rescue for the script's underdeveloped of v.4. So you think, that there are much more opportunities for using script in the qlc+ projects in the v.5, am I right?

[MichelSliepenbeek]

That wasn't me, I have never used v5 yet.

[prophy17]

Ou. I am sorry, Michel. It have been Mr GGGss message)))

[prophy17]

So my gratitude was for Mr Mishel and for Mr GGGss. Thank them very much.

[prophy17]

By the way. In my project loopback doesn't work with artnet plugin at the same time. Universe 1 - artnet input - loopback output. Universe 2 - loopback input. And doesn't work. With Separately files artnet and loopback work, but together not. What can it be?

[MichelSliepenbeek]

Of course this won't work.
If you are advised to use a separate universe for Loopback (and also use a separate universe for Artnet Input), you must be a dombo not to follow that advice.

Universe 1 - artnet input - loopback output.

Allthough you probably only use one channel, if you set a universe to ArtNet input you are going to receive the full 512 channels of that universe as input. So apart from that one channel you also get 511 channels with DMX value = 0 (zero) as a bonus.
They will overwrite (blank) whatever you further might have defined in that universe.

If you try to understand what you are doing here, this is basically a PassThrough. You set Universe 1 to receive Input from Artnet and then use the Loopback Plugin to reroute it to Universe 2. That makes no sense.

The universe you set to be output for Loopback should be a dedicated universe (not to be used for anything else).
In the same way you should use dedicated Universes for Artnet Input.

[prophy17]

Thank you for your answer, Michel. I don't reroute input from Artnet in Universe 1 to Universe 2 by Loopback, as you have written. I set some new fixtures of dimmers in the Universe 1 and make scenes with them. And in the Universe 2 I made the Loopback input profile. But I understand your advice to separate Artnet and Loopback Universes. And I'll try. Thanks.