@as1ama1and looping the video through a set of 3 shader actors does quite a good job. 

Freeze shader: grabs a frame at the start of each cycle and holds it. It does this through a feedback loop (output → pass-through shader → back into video in 2), because Isadora's GLSL actor has no persistent buffer.
Pass shader: an empty shader that just closes the loop.
Mix shader: lays the frozen frame over the live image and fades it out over time. blend mode decides whether the clone shows only where it's darker or lighter than the live image, so the live video is never covered.
A Wave Generator (sawtooth, 0–100) drives the clock input. One cycle equals one snapshot, so freq sets the cycle time.

Here's the patch: echo trails

Best Michel

@as1ama1and

try feeding the video into an Effects Mixer on channel 1 and running the output through a Video Delay into channel 2. By adding a Video Mixer into the loop you can control how much of the output feeds back into the input. Play with different blend modes until you get the effect that you like.

Howdy! 

I am trying to recreate a live version of the picture below. I made that picture by blending a few layers using a darken blend. For the live version, I want live feed with the stage being a tv. 

The idea is a dancer is in front of the camera standing still and then their small movements create the same effect which accumulates. Though at a certain point I'd want older layers to dissolve away completely. I know there are blend modes in the effect mixer actor but I don't know how to go about setting the rest up. Any help would be greatly appreciated!! 

@woland

When I first set it up. Stage 1 worked as expected then stage 2 got a signal but was blank. Stage 4 came through correctly, stage 5 suddenly was on stage 2 but projector 5 was blank and so on. Completely mixed up. I shuffled the stages around to get the order I wanted. On restarting it was thankfully the way I saved it. So that seems stable. 

I have an rtx 4090 and an rtx 3070 (externally mounted) and would like to use these cards also. My new challenge is that the display numbers for the decklink are the same as the display numbers for the 4090 displays and the 3070 displays. How can I get around this? 

Thanks for taking the time to respond to my dilemma,

Ray  

@bonemap

Great answer! 

All the best,

 Yar

Yes, it's named after the dancer/choreographer Isadora Duncan (no relation to the donut shops, I think)

@ray

On restart, or just completely randomly while the program is running?

Have you ensured the connections are all secure?

@rwillats

Me too. I feel it is a reference to the long, flowing silk costumes that she used to augment her movement.

I'd always assumed (or had seen somewhere and forgotten where) that it was after the dancer, Isadora Duncan!

@ray

My understanding is that the name 'Isadora' is an anadrome of 'Arodasi' a mythical place where the population of projection experts run backwards. I believe the creator of 'Arodasi' (really pronounced Isadora) comes from such a place and the software is named in for that honour.

Best Wishes,

llessur