The value of active_viewport_buffer cycles from 0 to 7.
I could not find any rule of the flashing. Is there anything I can do?
Since I don't have this camera, I can only guess.
platform/sx50hs/lib.c
vid_get_viewport_live_fb() currently only expects 4 buffers.
viewport_buffers seems to have at least 8 buffer addresses (?)
try replacing the final return statement in vid_get_viewport_live_fb() with
return viewport_buffers[(active_viewport_buffer-1)&7];or
return viewport_buffers[(active_viewport_buffer)&7];and see whether the situation is better or worse.
You can also test ptp live view with chdkptp, wrong buffer indices will result in jerky movements (or even random noise if an unused buffer is displayed).