My specs: Lenovo Thinkpad T530, external VGA monitor and internal laptop monitor, Intel HD4000. Both monitors have negligible front/back porch.
.exe demo is attached. Drag-right-click left and right to change the period. Drag-right-click up and down to change the phase. Esc to quit. It's easiest to see if you let the tearline slowly travel upwards; it'll snag at the very top. If you want to change phase but not period, keep your mouse to one of the screen edges.
Source code is also inside. My build command was
Code: Select all
g++ top_sync_jitter.cpp -std=c++1z -lglfw3 -lgdi32 -lwinmm -static -ob.exe -ffunction-sections -fdata-sections -Wl,--gc-sections -Ofast -DNDEBUG -fno-exceptions -fno-rtti -s