Delayed / Choppy Output to Pixels

[TheMediaDex]

Hello,

I recently upgraded to the latest version of LightJams - it has been working great for me but in the last couple of days of playing with the newest version I'm having some major output issues it seems.

I am using LightJams over ArtNet to a raspberry pi which is running 100 ws2801 LED pixels. Using any other software on the same machine over ArtNet (Jands Vista is what I'm using currently), I can output to this setup without issue, running fairly complex effects. But when I use LightJams my lighting setup only seems to update every 1-2 seconds, so it is very choppy. 

I don't understand why, since as I mentioned, LightJams has been perfectly fine up until the last couple of days.

Any help or troubleshooting would be greatly appreciated.

[Mathieu]

Hi,

Do you see any yellow or red indicators in Lightjams? This looks like a artnet configuration or network problem. Go in the artnet config panel (Ctrl-L, and then the artnet tab) and, if not already done, add a node with your raspberry pi IP to enable artnet unicast instead of broadcast.

Other things to help diagnose the problem:

- Do you see the same delay in the monitor?

- Can you see the problem in the artnetominator (http://www.lightjams.com/artnetominator/)?  

For further testing, you can send me your project directly to mathieu at lightjams.com or you can post it here.

Thanks,

Mathieu

[Mathieu]

Just to follow up, Ryan found the problem while talking with the OLA guys. It seems like OLA running on the raspberry pi can't keep up with all the packets Lightjams is sending. Initially the project contained 100 RGB leds and after adding 20 more, the delay problem starts appearing.

The response from the OLA forum is:

> Simon,
>
> netstat -lun | grep 6454
>
> comes back with:
>
> udp   164592      0 0.0.0.0:6454

 

            0.0.0.0:*
>

> Yup, the UDP Rx buffers are full. It means LightJams is sending ArtNet
> faster than OLA can process it and write the data over SPI.
>
> I need to put a rate limiter in place or move the SPI writes to a
> separate thread.

Lightjams sends 40 packets per seconds, which may be too much for a low powered device. I'm adding on my todo list a note to allow some frame rate limiter.

[Mathieu]

As of version 268, you can adjust the output rate. This is handy to avoid overloading low powered artnet nodes and also to reduce CPU usage for large projects. You can find these settings in the View/Configuration and general tab.

The input multiplier setting adjusts the rate at which inputs are processed. For example, to properly handle live MIDI notes played by a pro musician, you may need at least to process messages 80 times per second. So if the output rate is 40, then you need an input multiplier of 2 in order to get an input processing rate of 80.

However, when you don't need to process input messages that quickly and you have a low powered computer, consider using an input multiplier of 1.

For the output rate, if you have a large number of leds and want to save CPU, set it to about 25.