56cc2bd814
Optional skill: scroll-as-timeline landing pages on a deterministic CSS/JS engine, with interview → page grammar → signature move workflow and screenshot-based scroll verification. Engine and scripts vendored verbatim; asset generation re-anchored on image_generate with the upstream kie.ai flow kept as an optional path.
81 lines
3.1 KiB
Bash
81 lines
3.1 KiB
Bash
#!/usr/bin/env bash
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# scrollcraft: encode a clip for scrubbing, not for playback.
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#
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# A normal web encode puts a keyframe every 2-5 seconds. Scrubbing seeks to an
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# arbitrary time, and the decoder must walk from the previous keyframe to get
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# there, so a sparse-GOP file feels like mud under the wheel while playing back
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# perfectly. Dense keyframes cost file size and buy responsiveness. That trade
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# is the entire point of this script.
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#
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# ./encode.sh in.mp4 out.mp4 desktop master (1080p, -g 8, crf 20)
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# ./encode.sh in.mp4 out-m.mp4 mobile phone variant (720p, -g 4, crf 24)
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#
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# CRF override, for the grain-heavy worlds assets.md warns about (marine snow,
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# bioluminescence, smoke, film grain). A dense GOP doubles the cost of grain, so
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# a world like that wants 22-23 rather than the default 20:
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#
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# ./encode.sh in.mp4 out.mp4 desktop 23 fourth positional argument
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# SCROLLCRAFT_CRF=23 ./encode.sh in.mp4 out.mp4 or the env var
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#
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# The positional argument wins over the env var; with neither, the defaults
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# below are unchanged.
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#
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# Audio is stripped: these clips are scrubbed, never played, and a muted track
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# is dead weight plus an autoplay-policy hazard.
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set -euo pipefail
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# Resolve a FULL ffmpeg build. Several toolchains (Remotion, some Electron apps)
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# put a stripped ffmpeg on PATH that carries maybe 50 filters and silently lacks
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# scale/fps/tile. It fails with "No option name near ..." on any filter chain,
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# which reads like a syntax error in your command rather than a missing filter.
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# Count the filters and go looking for a real build if the count is low.
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pick_ffmpeg() {
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local cand
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for cand in \
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"${SCROLLCRAFT_FFMPEG:-}" \
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"$(command -v ffmpeg 2>/dev/null || true)" \
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"${HOME:-/nonexistent}"/AppData/Local/Microsoft/WinGet/Packages/Gyan.FFmpeg_*/ffmpeg-*-full_build/bin/ffmpeg.exe \
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/usr/local/bin/ffmpeg /opt/homebrew/bin/ffmpeg /usr/bin/ffmpeg /snap/bin/ffmpeg
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do
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[ -n "$cand" ] && [ -x "$cand" ] || continue
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if [ "$("$cand" -hide_banner -filters 2>/dev/null | wc -l)" -gt 200 ]; then
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echo "$cand"; return 0
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fi
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done
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echo "ERROR: no full ffmpeg build found. Set SCROLLCRAFT_FFMPEG to one." >&2
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return 1
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}
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FFMPEG="$(pick_ffmpeg)"
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FFPROBE="$(dirname "$FFMPEG")/ffprobe"
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[ -x "$FFPROBE" ] || FFPROBE="$(command -v ffprobe)"
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IN="${1:?usage: encode.sh <in> <out> [mobile|desktop] [crf]}"
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OUT="${2:?usage: encode.sh <in> <out> [mobile|desktop] [crf]}"
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MODE="${3:-desktop}"
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if [ "$MODE" = "mobile" ]; then
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SCALE="scale=-2:720"; GOP=4; CRF=24
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else
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SCALE="scale=-2:1080"; GOP=8; CRF=20
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fi
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# Positional beats env var beats the mode default.
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CRF="${4:-${SCROLLCRAFT_CRF:-$CRF}}"
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case "$CRF" in
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''|*[!0-9]*) echo "ERROR: crf must be an integer, got '$CRF'" >&2; exit 1 ;;
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esac
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mkdir -p "$(dirname "$OUT")"
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"$FFMPEG" -y -hide_banner -loglevel error -i "$IN" \
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-an \
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-vf "${SCALE}:flags=lanczos,format=yuv420p" \
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-c:v libx264 -profile:v high -preset slow -crf "$CRF" \
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-g "$GOP" -keyint_min "$GOP" -sc_threshold 0 \
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-movflags +faststart \
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"$OUT"
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SIZE=$(du -h "$OUT" | cut -f1)
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DUR=$("$FFPROBE" -v error -show_entries format=duration -of csv=p=0 "$OUT")
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echo "$OUT ${SIZE} ${DUR}s gop=${GOP} crf=${CRF}"
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