rotobrush out of memory when played, but ok if forward frame by frame

[avpromedia]

When using rotobrush if I click play, it works for a second or two and then display an orange bar saying I need to free up some memory, and then just loop back a second or two making no more progress.

Quitting all other adobe apps allows this to procecss a little more frames, but eventually the orange bar still appear.

Going forward frame by frame (PgDn) works fine. It never runs out of memory. I just get tired pressing PgDn. Why would "play" run out of memory? It's just repeating frame by frame automatically.

[Mohammad.Harb]

How much RAM is installed on your computer?

What is the dimensions of the comp ? 
Purge all memory from:  Edit -> purge -> purge all memory and disk cache 

[avpromedia]

Purging memory helps but eventually (after a few more seconds) I still get the low memory warning.

I allocated 20 G RAM to cc and closed all other adobe apps while running this.

I have 32G ram.

This still doesn't explain why frame-by-frame can run forever but playing runs out of memory.

[Byron Cortez]

Make sure you have enough RAM allocated to Adobe applications. You adjust this in the preferences, generally CC is allocated a third of your system's total RAM.