hey, so I’ve been following this tutorial: https://www.youtube.com/watch?v=pegsP5VoQIA&t=306s and at 5:19 she sets the output index to -88 and cache size to 9. when i do that, my source video disappears from the cache node’s window. but when i bring it back to -8, it comes back. i am wondering if i should personally stick to -8 and continue, but how much of a difference will it have on the final blob tracking effect? i’d also like to undersand how the integers in the output index and cache affect the frame rates. is there also a way i can set up a real time display of my current output with the nodes i have so far? i am a complete beginner so i apologise if this has been asked before. i have attached a photo of my screen below.
Hi @neur0chic
the Cache TOP records a sequence of images. How many images are recorded is determined by the Cache Size parameter. With the Active parameter on, it will fill the available space with previous images (in your case 8) and once filled, will throw out the oldest to make room for the next incoming image.
It looks like that in previous builds, if the Output Index parameter of the Cache TOP was larger than the Cache Size, the oldest recorded image was shown - in recent builds it shows black as the at the specified index there is no recorded image.
For your setup this means, to get the oldest recorded image in the cache, the Output Index parameter should be set to -(Cachesize - 1) - in your case -8
There is no effect on the framerate of TouchDesigner by changing Cache Size or Output Index unless you are choosing a Cache Size so high that your available graphics memory runs out. This would have to be in most cases an extraordinarily large number though.
Not fully sure what you mean by real-time output but I would point to our curriculum at learn.derivative.ca with the fundamental lessons giving you a quick overview of the principles behind TouchDesigner. For fullscreen output to a second display device, especially section 105 will help with output.
Hope this helps
Markus