leccaper

A University of Michigan lecture capture download tool, derivative of leccapdl. We use less automation on the navigation to the lecture capture page, to avoid some race conditions which can otherwise arise.

Usage

We require uv; pip can likely be used, but is untested.

uv venv ; . ./.venv/bin/activate
uv sync
leccaper

See leccaper --help for usage; the default is to download only the newest lecture for a course.

vf, vff

A couple of scripts, vf and vff, are bundled, and can be found in ./bin/. These are to convert a lecture video into a folder of slides, e.g.,

leccaper --number 1 ./captures/chem521/                      # Download the newest CHEM 521 lecture; say, lecture 13.
vf --width 960 ./captures/chem521/13.mp4 ./slides/chem521/13 # Split the lecture capture into deduplicated slides.

We use --width 960 here, as the slideshow in the lecture capture takes up the left 960 pixels. See vf --help for usage.

vff is simply a wrapper around vf, and can be used on a folder of lecture videos, e.g.,

leccaper --number 1 ./captures/chem521/               # Download the newest CHEM 521 lecture, as before.
vff ./captures/chem521/ ./slides/chem521/ --width 960 # Convert each capture in the input. Note the new argument order!

vf uses FFmpeg's mpdecimate filter; you can read the documentation at the top of the script for more information. It essentially scans for pixel differences, to discard consecutive slides which are too similar. This works pretty well to discard, e.g., laser pointer movements, but keeps slide transitions (even relatively subtle ones, like an arrow's appearance). If a video is played in the lecture slides, we cannot remove it, so this may balloon the number of slides generated; these images should be removed manually.