3 ms·

Cool project! Quick question: Is this https://imgur.com/a/V3iRPKf https://imgur.com/a/V3iRPKf an artifact of ghosting effect or refresh rate? How many FPS is th

Cool project! Quick question: Is this https://imgur.com/a/V3iRPKf https://imgur.com/a/V3iRPKf an artifact of ghosting effect or refresh rate? How many FPS is the video running at?

tverbeure 5y ago
I think it’s an artifact of desynchronized refresh rates between camera and cube. This is a video of Kbob’s cube, not mine, BTW.
- pupdogg 5y ago
  I've seen the same effect on actual LED screens in-front of me running synchronous content. So, a camera was not involved. This is why I ask becuase I've always wondered what might be causing this.
  - tverbeure 5y ago
    In that case, it’s probably due to a lack of double buffering.
kbob 5y ago
IIRC (I did this in 2018-19), the image updates at ~58 frames per second. There were numerous difficulties in making video of these. The LEDs' duty cycles are actually very short. HUB75 lights at most one row in 32 at any given instant. I shot all my video on an iPhone. The iPhone does who-knows-what processing to its video. It apparently does not scan top-to-bottom, but in bands, and it dynamically changes exposure times based on unknown heuristics. Here are some fails for your amusement. https://imgur.com/a/csSytw2 https://imgur.com/a/csSytw2 Recent gateware changes have increased the LED refresh rate to ~280 Hz, and that has changed and generally reduced video artifacts, but has not eliminated them. I can't tell you exactly what happened on the still you posted.