Movie in size 4k.

Hello. I have Ultra Fractal 6. The program has given me so much joy. I did short films in HD size and I did render to avi. Recently, I wanted to make a movie in size 4k. And problems began. The file renders to the end, but only 4 GB (approximately 160 frames) is saved. And he does not start from the beginning, but somewhere from the inside. Is it impossible to make a 4k movie with this program, do not I know something?
maria
(I am asking for short sentences because I do not speak English well.)

Hi Maria,

It should be possible to render in 4K format with Ultra Fractal. Are you rendering to AVI format or single images (for example PNG)? I would recommend to render to PNG and then create a movie from these later using a program such as VirtualDub (http://www.virtualdub.org/).

Ok I will try.

Thank you for the answer, Frederik. Rendering images and then making a movie is a good idea. I was worried whether VirtualDub could do it, but unnecessarily. Everything is OK.
I am looking forward to Ultra Fractal in the VR version.
maria