Time-lapse to video tool

A browser tool that turns the stills in a run's timelapse folder into an MP4 with an elapsed-time overlay, using the interval and start time from the run's experiment.json.

The Tools page has a new entry: time-lapse to video.

During a run the SciSpinner Max saves one still per interval into sessions/<name>/timelapse/ on the USB drive, numbered in capture order. The tool takes that folder, or the whole session folder, and produces an MP4. With experiment.json present it reads the interval and start time, so the overlay can show elapsed time from the start of the run or the date and time of each frame; without it, the interval can be typed in or the frame number shown instead.

The frame rate, output size (720p, 1080p or the original 2592 × 1944), quality and the range of frames are adjustable, and every Nth frame can be used for very long runs. A 24-hour run at 5-minute intervals is 289 frames, about 12 seconds of video at 24 fps; the page shows the speed-up and how much of the run one second of video covers.

Encoding uses the browser's own H.264 encoder, so the file plays in QuickTime, PowerPoint and on the web, and nothing is uploaded. Frames are read one at a time, so a run of several thousand full-resolution stills works on an ordinary laptop.