name: "cli-anything-quietshrink"
description: Compress macOS screen recordings with zero CPU stress using Apple Silicon's hardware HEVC encoder. Typically reduces file size 70-90% while staying visually lossless. Computer stays silent during encoding.

quietshrink — Agent Skill#

You have access to cli-anything-quietshrink, a CLI for compressing video files on macOS Apple Silicon. It uses the Media Engine (hardware HEVC encoder), not the CPU, so encoding is fast and silent.

When to use it#

User wants to compress a screen recording, screencast, or any .mov/.mp4 file
File is too large to share (chat, email, GitHub)
Need smaller files but cannot tolerate visible quality loss
Apple Silicon Mac (M1/M2/M3/M4) — best results

Don't use this on non-screen content (camera footage, vlogs) — savings will be much smaller because there are no duplicate frames to drop.

Commands#

# Compress with default transparent quality
cli-anything-quietshrink compress <input> [output]

# Compress with specific preset
cli-anything-quietshrink compress -q tiny <input>     # smallest
cli-anything-quietshrink compress -q transparent <input>  # default, visually lossless
cli-anything-quietshrink compress -q pristine <input>     # near-source quality

# Inspect a file before compressing
cli-anything-quietshrink probe <input>

# List quality presets
cli-anything-quietshrink presets

# Verify environment
cli-anything-quietshrink doctor

All commands accept --json for machine-readable output.

Quality presets#

Preset	q	Typical reduction	SSIM	Use case
`tiny`	50	~90%	~0.95	Chat/email — small artifacts OK
`balanced`	55	~88%	~0.99	Docs/sharing — high quality
`transparent` (default)	60	~87%	~0.99+	Anything important — visually lossless
`pristine`	70	~84%	~0.997	Archival — near-source

JSON output schema#

compress returns:

{
  "input": "/path/to/input.mov",
  "output": "/path/to/output.mov",
  "input_size": 105952129,
  "output_size": 12345678,
  "saved_bytes": 93606451,
  "saved_percent": 88.3,
  "duration_seconds": 193.3,
  "elapsed_seconds": 87,
  "encoding_speed": "2.2x",
  "quality_preset": "transparent",
  "q_value": 60,
  "gop": 600
}

probe returns:

{
  "path": "...",
  "size_bytes": 105952129,
  "size_mb": 101.04,
  "codec": "h264",
  "width": 3024,
  "height": 1964,
  "framerate": "120/1",
  "duration_seconds": 193.31
}

Decision flow for agents#

User wants to share a recording
  ├─ Is it on Apple Silicon Mac? → use quietshrink
  │  ├─ For chat/email/quick share → -q tiny
  │  ├─ For docs/important sharing → -q transparent (default)
  │  └─ For archival/editing → -q pristine
  └─ Not on Mac? → falls back to software, less efficient

Before processing, run doctor to verify environment.
For unfamiliar files, run probe to understand resolution/codec/duration.

Errors and recovery#

ffmpeg not found → brew install ffmpeg
hevc_videotoolbox not available → brew reinstall ffmpeg
compression_failed → check input file isn't corrupted; try --verbose mode to see ffmpeg errors

Source#

Main repo: https://github.com/achiya-automation/quietshrink
Bash CLI: quietshrink command (via the install script)
Why this approach works: see WHY.md