Jerkiness and missed pixel updates?

[a6345634]

Just starting to test ELM with a fixture. Using a Smartshow Lighting Netpixel Quad as a controller via Artnet. A couple of things I've noticed.

With Artsync and Optimise OFF, the pixels update fine, but there is a little jerkiness on the lights, whereas the monitor seems smooth. Similar to the problems with film and video with 50Hz, 60Hz and 24Hz. It is not a serious problem, but I notice it.

With Optimise ON, some pixels are being missed and stay on after they should have switched off. Artsync makes the problem worse.

I have tried setting DMX fps to 44, and 25. There is no change to the behaviour whether I use a direct network connection between the controller and the PC, or whether it goes via my LAN.

My setup is 3 strings of 208 LEDs. Each string driven by 1 output on the controller. I am using the simple vertical swing effect in ELM to test.

I've messaged the maker of the controller to see what he suggests. Anything I should check with ELM? I have tried Lightjams as well and get similar behaviour.

[Mathieu Lightjams]

If you tried 25fps with optimize OFF and still see strange things, it's not normal. Make sure your network is not too busy and contact the LED controller manufacturer.

[Mathieu Lightjams]

On the manufacturer page, it's written that the maximum fps is 25. So lower it a little bit in ELM to make sure it stays under 25. Try 20 or less. Also make sure to enter the IP address of the controller in the Art-Net configuration page for each universe in order to unicast data. It is recommended by the manufacturer of your controller. Maybe broadcasting overloads the controller.

[a6345634]

I have tried the following

1. fps dropped to 20 - no change

2. Confirmed it is set up as Unicast - IP address populated in ELM Artnet screen

3. It works with Optimise OFF and ArtSync OFF, but I need it to work with both these on as eventually the fixtures will be on WiFi.

4. Tried using 2 different PCs running ELM. One PC was connected directly to the controller - no switch in the way. No change in behaviour.

5. Downloaded MadMapper demo. This works perfectly, smooth and no missed pixels. I believe MadMapper enables ArtSync and Optimise by default.

The MadMapper test was interesting. Do you know of any differences between how ELM/Lightjams send data compared with MadMapper?

I've asked the controller maker whether there is any logging that can be done.

[James Walton]

Hi,

From speaking with friends in the past, I'm fairly sure Bobby's Smartshow devices don't have the ability to work with optimised frames due to their buffer size and the increased processing power it requires to support it (also the reason for a max frame rate of 25fps). I'm fairly sure the AirPixel is based on an ESP8266 board.

I couldn't comment on SmartShow devices, but personally I've used MadMapper and ELM on a number of DMX and pixel nodes and not run into any issues with any of ELM or MadMappers ArtNet settings.

Have you checked with Bobby that the AirPixel has full support for both optimised frames and ArtSync?

For a controller at such a low price point it wouldn't surprise me if a couple of features had to be left out along the way to make the firmware fit on the board.

I'm definitely keen to hear the outcome.

Thanks,

[a6345634]

Thanks for the comment James, I am using the Netpixel Quad devices and Bob has said that they support Artsync and Optimise. He also said that the max FPS is determined by the max length on each output. If only using max 2 universes on each output then 44 FPS would be fine. The price and feature set of the NPQ devices is very similar to the DMXKING LeDMX4 Pro which would have been my alternative.

I've sent Bob the link to this thread. I hope between Mathieu and Bob the Smartshow devices can be made to work properly with Lightjams and ELM

[James Walton]

Perfect, I've learnt learnt something new there! I had no idea that FPS could be adjusted.

Definitely going to keep following this one.

[Mathieu Lightjams]

Is it the Optimize or the ArtSync that is causing the jerkiness? I mean, if you only activate ArtSync and not the Optimize, does it look ok and vice-versa?

[a6345634]

for now, I'm more concerned about missed pixels and strange behaviour. Here is a video of a basic sweep in ELM.

https://www.youtube.com/watch?v=_0CL1yZXBiI

ArtSync Off, Optimise Off - Sweep OK

ArtSync On, Optimise Off - Sweep OK

ArtSync Off, Optimise On - Sweep down Not OK (as per video)

ArtSync On, Optimise On - Sweep down Not OK (as per video)

The pixels are now all on one controller output which uses 4 universes. The 1st pixel is at the bottom right, and then goes up, down, up, down, up, down. from right to left.

[Mathieu Lightjams]

I've modified something for the optimize in the latest ELM beta v420. You can try it :

64-bit: https://www.lightjams.com/app/elm/ELM64_test.msi

32-bit: https://www.lightjams.com/app/elm/ELM32_test.msi

[a6345634]

Hi Mathieu, 1st test shows I now get the correct behaviour for all values of Optimise and Artsync.

Out of interest can I ask what you modifed?

For the jerkiness problem I have done a comparison with Madmapper and ELM while varying the speed of the up/down sweep and they seem to behave the same. At some speeds, the LED movement is slightly jerky. I assume this is just refresh and motion rates interacting, so happy to close the question.

[Mathieu Lightjams]

I disabled an optimization (sending only the channels that changed) that not many LED controller manufacturers support (unfortunately). Most Art-Net node manufacturers know about this, but for some reasons, recent LED controller manufacturers have forgotten about this... At the end, it may not be worth doing this optimization since it's causing confusion and finger pointing.

> At some speeds, the LED movement is slightly jerky

Well, a LED controller is pretty low powered and at some point it gets overloaded and starts missing DMX packets.

[a6345634]

So does the optimise button do anything now? I was interested in doing everything I could to reduce network traffic because these fixtures will be on wifi in unknown RF environments.

[Mathieu Lightjams]

Yes it does. Only the universes that have been modified are sent. However, if your WIFI network isn't reliable, the LED controller will miss updates and you'll see jerkiness again. And if your WIFI network can't handle sending all universes, then you'll also see jerkiness sometimes. So you may end up reducing the fps and disabling the optimize anyway!

[a6345634]

Having done some more testing, I'm fairly sure the jerkiness is related to the DMX output rate which is now set to 44fps. If I'm doing a sweep that's quicker than about 3 seconds from top to bottom, then that means the sweep is travelling up the LEDs at more than 22 LEDs per second. So every so often it will need to "catchup" a LED which is where I see the jerkiness. It is smooth below 22 LEDs per second, and smooth at exactly 44 LEDs per second, which is all explainable by theory.

Thanks for your help as always Mathieu. All solved now. :-)

I'll report back when I do some wifi tests.