Video reference compare

Compare what was made against what it is meant to match, one frame at a time. A 2fps overview hides everything that matters in motion work: one-frame flashes, where a line starts growing, the frame a cut lands on, a glow that spreads too wide.

The tool is scripts/refcompare.js next to this file (in this skill's base directory). It needs only Node and ffmpeg/ffprobe, and runs on macOS and Windows.

S=<this skill's directory>/scripts/refcompare.js
node $S ref.mp4 ours.mp4 out.png --range 1.9:2.4            # every frame, native rate
node $S ref.mp4 ours.mp4 out.png --tc 9:03,21:16             # editor timecodes (s:frame)
node $S ref.mp4 ours.mp4 out.png --times 0.367 --crop 0.3:0.3:0.4:0.4 --width 640   # zoom a detail
node $S ref.mp4 ours.mp4 out.png --range 11.2:11.45 --diff   # where do they differ?
node $S ref.mp4 ours.mp4 out.png --range 13:14 --offset 0.0667   # candidate cut sits 2 frames later