[dependencies]
video = "^0.1.0"

video

Turn a video file into ordered JPEG frames — MJPEG AVI in pure NURL, everything else through ffmpeg when it is installed.

video frames walk.avi --fps 10        # -> walk_frames/000000.jpg ...
video frames trip.mp4 --out frames/   # any container, via ffmpeg
video probe  walk.avi                 # what the AVI parser sees
video walk.avi                        # shorthand for `frames`, fps 10

Why MJPEG is special

An AVI is a RIFF tree, and an MJPEG frame chunk is a complete JPEG. Extraction is therefore parsing, not decoding: walk hdrl/strl for the frame rate and the video stream index, walk movi for the NNdc chunks, write the sampled ones to numbered files. No codec, no ffmpeg, no dependency. Cameras, OBS (ffmpeg -c:v mjpeg) and phone apps can all record MJPEG.

Every other container (H.264/MP4, HEVC, VP9, MKV, WebM) needs a real decoder, and that is ffmpeg's fight; when it is on PATH it is used with the same fps sampling, and when it is not the error says what to install or how to record instead.

Library

$ `deps/video/src/video.nu`

( vid_is_video path )                     → b        the extension is a video's
( vid_frames_dir path )                   → String   <dir>/<stem>_frames
( vid_extract path fps outdir verbose )   → !i String   frames kept
( vid_avi_open path )                     → !VidAvi String
( vid_avi_extract v outdir stride )       → !i String
( vid_avi_close v )                       → v

vid_extract is the front door: it creates outdir, removes exactly the frames a previous extraction left there (six digits + .jpg/.png, nothing else — a shorter run must not inherit a longer run's tail), and keeps every round(src_fps / fps)-th frame.

Tests

./tests/video_test.sh

The fixture generator (tests/make_avi.py, Pillow + struct, no ffmpeg and no cv2) doubles as documentation of the exact container layout the parser reads.