Why is it stupid to use Art-Net to control digital LED pixels?
The fact is, most of the digital LED pixels, LED bars or LED strip installations in the world are controlled using Art-Net. But is it really a good idea? Recently we’ve talked about this with my colleague and here are our thoughts.
What is Art-Net and how it controls digital LED pixels?
Art-Net is generally DMX over Ethernet cable. You can read more technical details about Art-Net at Wikipedia. The basic part of the protocol is so-called universe. It’s one chunk of 512 numbers (from 0 to 255) – for more technical guys, it’s just 512 bytes. In the Art-Net world we call these bytes as channels.
The universe is send over Ethernet cable to other devices connected to network, ideally at more than 40 frames per second. You can use several universes in one network (thousands).
In the digital LED pixel world, the channels are used to control Red, Green and Blue color of single LED pixel. You need 3 channels to control one RGB pixel. It means, you can control up to 512/3 = 170 individual LED pixels using one Art-Net universe.
As you can see, the last two bytes of the universe can’t be used. You would just control R and G of the 171-th pixel and you would need to use the 1st channel of next Art-Net as blue value. Complete mess.
How do you convert Art-Net to digital LEDs?
You need to use additional device called Art-Net to SPI converter. It converts the RGB channels to so-called SPI signal, which is send to digital LED pixels. There is of course additional complication – there are several types of SPI signal. You need to take care, your Art-Net to SPI converter supports the type of digital LED you use. There are numerous of SPI signals/types of digital LEDs: WS2811, TM1809, APA, ..
How many Art-Net universes I need?
The calculation seems simple. Imagine you need to control 1000 LED pixels. You’ll need total of 1000/170 = 6 Universes (5.88 to be precise, but you can’t use just part of universe).
Typical calculation when using Art-Net for customer is – “I need to control 100 meters of digital LED strips using 30 pixels per meter”. You, as a technician, must calculate 100*30= 3000 RGB pixels, so it’s 3000*3=9000 RGB channels. Thus, I’ll need 9000/510 = 17.64, total of 18 universes.
Of course, there’s even more problems, since one device can typically use e.g. 4 universes. So again, you’ll need to divide 18 Universes by 4 – additional calculation.
As you can see, you need a lot of thinking just to calculate how many Art-Net universes you need. It’s just too much overhead. Wouldn’t it be easier to know, my device can control up to 4096 individual RGB LED pixels?
What are the cons of using Art-Net to control digital LEDs?
The protocol was invented long time ago. Before it was actually used to control digital LED pixel installations. That’s why there are few issues when using Art-Net:
- 170 RGB pixels per one universe is really not handy to calculate
- One universe is not using last two channels
- You can use typically 4, 8, or more Art-Net to SPI converters – additional “level” of calculation
But there are also technical issues because of the age of Art-Net. The most important:
- The protocol is uncompressed. Its raw protocol using uncompressed data, which can be huge for big installations. This is especially bad for wireless networks.
- It’s working over UDP network protocol, which is not safe. It doesn’t guarantee, the data will actually arrive to destination (Art-Net to SPI converter).
- There is no way for the SPI converter to know, there is an end of frame. The companies use different “tricks” or “hacks” using so-called magic packets to solve this. But it’s different for every company making the Art-Net signal not completely compatible.
- It’s not safe against hackers – the UDP data can be easily hacked.
Are there any pros for Art-Net?
Yes, there is one big advantage and that’s compatibility. If you need to control your digital LED pixel installation from standard lightning console like Avolites, MA Grand or ChamSys, you can do that using Art-Net.
But there is also an option to avoid using Art-Net and “big” lightning consoles. Since LED Strip Studio software can grab HDMI signal, you can use this option to send HDMI signal from your media server to your digital LED pixels.
How does the typical LED Strip Studio installation calculation look like?
We’ve tried to simplify the digital LED pixel installations since the beginning of developing LED Strip Studio. If your installation requires 1000 pixels, you can use our LED Ethernet Controller 3 (LEC3). LEC3 lite device provides 1024 pixels. If you need more – you can purchase LEC3 version allowing you to control 2048 or 4096 pixels. That’s all you need to know. No messing with universes, channels, byte-alignment or how many channels/universes my SPI converted can handle.
Just straightforward calculation – I need to control 10000 pixels, I’ll need 10000/4096 = 3 LEC3 devices. This really simplifies the calculations and also save a lot of money. If you calculate the price per individual LED pixel, LED Strip Studio software and hardware is one of the most affordable in the market.
Benefits of using LED Strip Studio to control digital LED pixels:
- The video data is compressed in real time. This saves about 80% of your Network capacity. The performance even over wireless networks is great.
- We use TCP Network protocol – the data always arrive where they supposed to.
- The data is encrypted, no hackers can get to them.
- No need to handle stupid 170-pixel Universe calculations.
- Easy setup – just drag and drop your 1000-pixel strip to mapping.
Will we ever get rid of Art-Net for digital LED pixels?
In our experience, it won’t happen. The “old” installation companies are used to use this protocol and they don’t really want to try new things (because “it was working before”). But from our point of view – using Art-Net to control your digital LED installations is like using phone with physical keyboard instead of an iPhone (or Android device).