100 lines
4.6 KiB
Markdown
100 lines
4.6 KiB
Markdown
---
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name: screenstudio-alt
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description: "Open-source headless Screen Studio alternative: auto speed-up of idle, auto-zoom on click clusters, keystroke overlay chips, smoothed synthetic cursor, and 9:16 vertical export that follows the action — post-production for screen recordings from the CLI."
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risk: critical
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source: community
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source_type: community
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source_repo: connerkward/screenstudio-alternative-skill
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date_added: "2026-06-16"
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author: Conner K Ward
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license: MIT
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tags:
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- screen-recording
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- video
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- post-production
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- auto-zoom
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- vertical-video
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- ffmpeg
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tools:
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- claude-code
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- antigravity
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- cursor
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- gemini-cli
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- codex-cli
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plugin:
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targets:
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codex: blocked
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claude: blocked
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setup:
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type: manual
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summary: "Screen/input capture requires sensitive local permissions; keep out of plugin-safe bundles."
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docs: SKILL.md
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---
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## When to Use
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Use when polishing a screen recording / demo video for sharing, when the user mentions Screen Studio, auto-zoom, idle speed-up, or vertical/social video from a screen capture, and for any social-facing demo (vertical output is the default for those).
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_Source: [connerkward/screenstudio-alternative-skill](https://github.com/connerkward/screenstudio-alternative-skill) (MIT)._
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# screenstudio-alt
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The skill's code lives in this directory (`polish.py`, `render.py`, `studio.py`,
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`events-log.swift`, test fixtures, etc.). Published publicly as
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`connerkward/screen-studio-alternative` via the publish-skill skill.
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Two components:
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- `events-log` (Swift) — capture-side input logger (cursor 60Hz, clicks, keys;
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drops keys during macOS secure input). Runs ONLY while recording. Needs
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Accessibility/Input Monitoring for the terminal. **Auto-zoom/keys/cursor need
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this data at capture time — it cannot be recovered from pixels later.**
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- `polish.py` (Python, ffmpeg + PIL) — the post-production pass:
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```bash
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python3 src/polish.py in.mp4 --events in.events.jsonl \
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--speedup # compress idle (input-gap ∩ frozen-pixels; animations stay 1x)
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--zoom # eased auto-zoom on click clusters (zoompan)
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--keys # accumulating keystroke chips (PIL overlays, no drawtext dep)
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--smooth-cursor # synthetic eased cursor (best with sck-record --no-cursor)
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--vertical # ALSO emit 1080x1920 following the action
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```
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`--speedup` works WITHOUT events (freezedetect only) — usable on the whole
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existing dailies corpus.
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- `render.py` — **high-quality non-destructive renderer** (preferred): single-pass
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spring-physics camera over the original high-res frames, LANCZOS into a smaller
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target (crisp zoom, ~1.3× sharper than the ffmpeg upscale path), 60fps, H + 9:16 V.
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Tunable `--freq`/`--zeta` (spring), `--fps`, `--target-w`. Takes explicit
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`--regions [{t0,t1,z,cx,cy}]`. `polish.py` is the older ffmpeg-filter fallback.
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- `studio.py [recording.mp4]` — local web UI, **NLE-style fixed-ruler timeline** (bar =
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source duration, never rescales → upstream always planted): zoom regions are draggable
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blocks (move / retime edges / click to add / double-click delete); idle spans are
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**speed blocks with rate-only editing** — source range locked, rate set via inspector
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slider on select or right-edge **rate-stretch** drag (FCP retime / Premiere Rate
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Stretch); rate changes ripple downstream only. Tunable cosine-ease ramp, default zoom,
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aspect, frame styling. Always-smooth synthetic cursor + click ripple + real recorded
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click sound (CC0 #735771). Export uses render.py. Free port, local. (Keystroke overlay
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exists in the engine but is off by default.)
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## Easy path
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`screencast.sh --demo` (screencast skill) does the whole chain: starts the event
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logger, records, then polishes + emits the 9:16 vertical automatically. Vertical
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is the DEFAULT for social-facing demos.
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## Gotchas (learned the hard way, kept here so they're not relearned)
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- ffmpeg CANNOT do animated `scale=eval=frame` → `crop` (link reinit wedges crop's
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per-frame exprs). That's why zoom uses `zoompan` (no `t` var there — use `on/FPS`).
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- This machine's ffmpeg lacks `drawtext`; all text/cursor overlays are PIL-rendered
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PNGs + `overlay`.
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- Test rig: `make-fixture.py` synthesizes a fake screen recording + ground-truth
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events.jsonl — validate any change against it before trusting real footage.
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## Limitations
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- The workflow assumes FFmpeg plus the companion scripts are available locally; it is not a hosted video editor.
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- Polished cursor, click, and keystroke effects depend on event logs captured during recording; missing logs limit what can be reconstructed.
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- Auto-zoom and idle speed-up still need human review for pacing, framing, and platform-specific taste.
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