out of memory – FFMPEG : When utilizing a filter complex script on large duration and sized videos, it eats up the RAM entirely. Request a fix

I am using ffmpeg to blur certain areas of a large video file using boxblur.

Using over 1000 redactions in the filter script, When I generate a ffmpeg command to apply these complex filters( create redaction areas and then overlay them) on a 1 GB video, I get ffmpeg is out of resources, ram gets used totally by the redactions and the overlays. Thus the output video is not obtained.

I tried two ways:
a. First way using split to create 1000 streams, create redaction areas from them using boxblur and then overlay on top of each other in cascading effect. This generates out of memory as soon as it is run.

b. In the second way, I do not split into streams at the start but generate redaction areas from the original input video and then overlay them on top of each other in cascading way. This slowly eats up the ram and breaks.

Request help:

a. For large video size(>1gb) and large number of redactions(>1000) is there an efficient way to generate ffmpeg filter_script so it does not use my ram entirely and outputs the result in lesser time.

b. Are there any alternate ways to do this using ffmpeg.