Q Light Controller+

Hello!

I am planning a light installation and would like to know if QLC+ with Raspberry Pi would be a good fit. Here's what I am trying to do:

Light source will be LEDs, most likely the WS2812b or the APA102. I have a pixel controller (http://www.advateklights.com/shop/home/ ... ugged.html) that takes Art-Net in and translates to pixels, so I will want to have QLC+ from the RPi having an Art-Net out.

I will have about 3000-4000 pixels controlled and I'm wondering if this is too big of a job for QLC+ or for the Raspberry Pi, since I haven't used QLC+ on it before. What do you all think?

Thank you!

Ethan
Savory Lighting Design
Portland, OR, USA

Hi Ethan,
well, you have already reached the limit on a desktop PC, so I'd say 3000-4000 pixels on a RPi is pretty much an hazard

When I published my first video back in 2014, there was only the Raspberry Pi 1 and I was able to control around 900 DMX channels, mixed between SPI and USB interfaces.
With the newest RPi products I'd say the situation has improved quite a lot, and the fact you're planning to use ArtNet can help it, but still you have to face the fact that the QLC+ engine has a scalability limit, which unfortunately doesn't properly use all the cores available on a CPU.

Also, it all depends on how you design your project. As discussed before, RGB matrices are more efficient than Scenes on a large pixel installation. So I'd say you can control quite smoothly something like 2000 pixels with a single RPi 3, but I wouldn't guarantee much more than that.

Otherwise, you can play on a higher level than that. History teaches that when one processing unit is not enough, you need to scale on a multiple core architecture.
For example you can setup 3 RPis, and split the workload. Basically one "master" RPi can start/stop Functions on the other 2 "slave" RPis through let's say OSC commands over the network. Obviosuly you need to design the show considering the possibility that the 2 "slave" RPis can receive delayed commands so you might end up having 2 parts of the show not synced by a few milliseconds.

I think someone in this forum can even suggest to directly connect RPi GPIOs directly between each other, to bring that delay down nearly to zero ms.

Those are just rough ideas, but if you succeed in animating 4000 pixels with RPi(s) it would be definitely a use case to show to QLC+ users !

That's great input. I would imagine that it is possible to use the master RPi to send time-based OSC signals as well, since QLC+ does not, correct? This could launch those sequences based on the universal time on the RPi time and enable me to have time-based matrices. Cool! I will keep you guys updated on the progress! Thanks as always for your help!

Ethan

I may actually use my computer instead of a RPi. I would use qlab to send a midi cue to QLC at certain times.

You may want to look into some of the Christmas lights forums, specifically Falcon Christmas. They have developed a pi software solution (falcon player) that may be a good fit for your playback. It'll playback shows from a usb flash drive, has a scheduler, you can deploy multiple pis on a network in a master slave config, also works as an artnet/e131 bridge. Users there report being able to deploy 10k+ installations with this setup.

They recently came out with a pi cape that offers 2 fused spi pixel outputs (I think ws2811 only) and one dmx output with an rtc chip for $35.

I've been toying with using pi's (qlc+ software) and a falcon pixel controller with very good results on a small matrix (512 pixels) with very good results.