#!/usr/bin/env bash
# Extract a clip to a PNG sequence for the take builder.
#
# Frames are pre-extracted rather than decoded in the page on purpose: browser
# video seeking by currentTime is approximate and requestVideoFrameCallback only
# delivers frames at playback speed, so neither gives a deterministic per-frame
# pass. A PNG sequence is exact, instantly seekable, and reproducible.
set -euo pipefail

src="${1:?usage: ./extract.sh CLIP [FPS] [OUTDIR]}"
fps="${2:-24}"
out="${3:-frames}"

rm -rf "$out"
mkdir -p "$out"
ffmpeg -hide_banner -loglevel warning -i "$src" -vf "fps=$fps" "$out/%04d.png"
echo "$(ls -1 "$out" | wc -l) frames at ${fps}fps -> $out/"