About px4-flow make all

I downloaded the source code from Github, and I went back to the version in December 2014. When I compiled, there was a problem of Itoa and Itoa function redefinition. I modified the name and compiled successfully, but I found that when I blocked the camera, the optical flow data would stop, and the quality could not reach 255. So I want to ask, is it my environment configuration problem?

If you block the camera, how do you expect it to calculate optical flow?

But the source firmware THAT I downloaded from the website was downloaded to the board, and even if I blocked the camera for a long time, the data didn’t stop, it kept changing, and the quality remained 255 output