Can this browser pull one frame out of a stored mp4 and turn it into a JPEG? Open the bench, paste a video URL, press Run. The two picker pages answer the next question — which second the cover should come from.
cover-filmstrip.htmlPICKER Pre-renders every whole second of the first ten as a clickable grid, so a cover is chosen by looking rather than by typing a number. Auto-selects the first non-black frame. cover-scrubber.htmlPICKER Scrub one second at a time — wheel, slider or arrow keys — and watch the cover each second would produce. The second on screen is always written into the timestamp field. capture-bench.html Runs three capture techniques against the same video and reports time, phases, output size and mean luminance for each. cors-test.html Narrower check: canvas tainting and toBlob only. Superseded by the bench, kept because it isolates the CORS question.