A standalone, headless media-processing engine: 19 ffmpeg recipes for video, audio, and still images, defined once in a single operations registry and driven through three interchangeable faces — a CLI, an MCP server, and a drag-and-drop web UI. The engine and two of the three faces are pure Python stdlib; ffmpeg is the only external binary. Everything runs locally — your files never leave your machine.

_{The web UI running video_to_gif — drag a file, tune the auto-generated form, watch ffmpeg run live. Same page, hue knob rotated: every accent is one CSS variable and shader/canvas uniform, so the whole palette and the animated background recolor instantly (and the motion can be paused to save resources).}

_{Dogfood note: these screenshots were downscaled for the repo with media-engine itself —
python3 cli.py run resize_image -i shot.png -o assets/screenshot.png --imageResizePreset manual --imageCustomWidth 1200 --imageCustomHeight 550}

                      ┌──────────────────────────────┐
  cli.py ────────────►│                              │
  server.py (MCP) ───►│   OPERATIONS registry (19)   ├──► ffmpeg
  webserver.py ──────►│   validate → probe → build   │
                      └──────────────────────────────┘

Add an operation once and it appears in all three faces automatically — as a CLI subcommand, as a typed MCP tool, and as an auto-generated web form. Zero per-face code.

Contents

• Highlights
• Quick start
• The three faces
  • CLI
  • MCP server
  • Web UI
• Operations
• Architecture
• Portability
• Provenance
• License

Highlights

• One registry, three faces. Every operation is a declarative Operation entry (typed params, an ffmpeg command builder, an output-extension rule). The CLI, the MCP server, and the web UI are thin projections of that one registry.
• Zero dependencies. The engine, the CLI, and the web UI need nothing but Python and ffmpeg — no pip install, no venv, no build step. Only the MCP face pulls in one package (fastmcp).
• Runs on old and new ffmpeg. A version probe picks -fps_mode (ffmpeg ≥ 5) or the legacy -vsync automatically, so the same code runs on a stock Ubuntu ffmpeg 4.4 and on current builds. All 19 operations are verified end-to-end on ffmpeg 4.4.2.
• Honest progress. Progress comes from ffmpeg's machine-readable -progress pipe:1 stream, not from scraping locale-dependent stderr — it feeds the CLI progress line and the web UI's live SSE updates alike.
• Local and private. No network calls, no telemetry, no cloud. The web UI binds 127.0.0.1 by default and processes uploads in throwaway temp workdirs.

Quick start

git clone https://github.com/constant-itis/media-engine.git
cd media-engine

ffmpeg -version        # any reasonably recent build; 4.4+ verified

# CLI — no install at all
python3 cli.py list
python3 cli.py run video_to_gif -i clip.mp4 -o clip.gif

# Web UI — no install either
python3 webserver.py   # then open http://127.0.0.1:8765

# MCP server — the one face with a dependency
pip install -r requirements.txt
python3 server.py

If ffmpeg/ffprobe aren't on PATH, point at them with the FFMPEG_BIN / FFPROBE_BIN environment variables.

The three faces

CLI

python3 cli.py list                 # all operations, one line each
python3 cli.py info <op>            # params, types, ranges, defaults
python3 cli.py run  <op> -i IN -o OUT [--param value ...]

Real examples:

# two-pass palette GIF at 15 fps, 480p
python3 cli.py run video_to_gif  -i clip.mp4  -o clip.gif  --gifFpsPreset 15 --gifResolutionPreset 480p

# 50% faster, video and audio kept in sync
python3 cli.py run video_speed   -i clip.mp4  -o fast.mp4  --speed 50

# transcode to opus with EBU R128 loudness normalization
python3 cli.py run convert_audio -i song.wav  -o song.opus --audioFormat opus --normalizeLoudness true

# watermark, bottom-right, 18% of frame width
python3 cli.py run add_watermark -i clip.mp4  -o marked.mp4 --coverImage logo.png --watermarkPosition bottom-right

# print the exact ffmpeg command(s) without running them
python3 cli.py run video_to_gif  -i clip.mp4  -o clip.gif  --dry-run

Every param takes a value (booleans included: --gifExportWebp true). run also accepts --threads N, --quiet, and --dry-run — dry-run prints the fully-assembled ffmpeg invocations, which doubles as a recipe reference.

MCP server

server.py exposes the registry over the Model Context Protocol as a stdio server — one typed tool per operation, auto-generated from the same OPERATIONS registry. Choice params become enum-constrained schema fields, numeric ranges and defaults carry over, output_path is optional (derived next to the input as {stem}_{op}.{ext}), and every tool accepts dry_run. A list_operations tool covers discovery.

pip install -r requirements.txt      # fastmcp — the engine itself stays stdlib
python3 server.py                    # stdio entrypoint your MCP client launches

Register it with any MCP-compatible client:

{
  "mcpServers": {
    "media-engine": {
      "command": "python3",
      "args": ["/absolute/path/to/media-engine/server.py"]
    }
  }
}

Tool results return the output path, the ffmpeg command(s) run, and pass counts; failures come back as {"ok": false, "error": ...} with the ffmpeg stderr tail.

Web UI

webserver.py serves a single-page drag-and-drop UI over stdlib http.server — no frameworks, no build step, no dependencies. The whole frontend is one self-contained web/index.html (vanilla JS, inline styles, embedded font and icons).

python3 webserver.py                      # http://127.0.0.1:8765
python3 webserver.py --host 0.0.0.0 --port 9000

Drop in a file, pick an operation (deep-linkable as /#video_to_gif), tweak the auto-generated parameter form, run. The op executes in a background thread inside a temp workdir, progress streams live over Server-Sent Events, and the result previews in-browser (image/video) with a download button. Abandoned jobs are reaped after 30 minutes.

The HTTP API underneath is plain and scriptable:

Route	Method	Purpose
/	GET	the UI (web/index.html)
/api/operations	GET	full registry as JSON (params, types, ranges, defaults)
/api/run/<op>	POST	multipart upload (file field __input__ + param fields) → {job_id}
/api/progress/<job_id>	GET	live progress as an SSE stream
/api/result/<job_id>	GET	download the output (one-shot; workdir cleaned after)
/health	GET	liveness check

Security note: the server runs ffmpeg on uploaded input and binds localhost by default. Don't expose it to an untrusted network.

Operations

19 operations — 10 video, 5 audio, 4 image. Full parameter details for any op: python3 cli.py info <op> (or /api/operations, or the MCP tool schemas — same data).

Video

Operation	Description	Params
video_to_gif	Video to animated GIF (two-pass palette) or WebP	gifFpsPreset gifResolutionPreset gifExportWebp
video_speed	Speed up / slow down video + audio in sync (atempo-chained)	speed (−100…100 %)
add_watermark	Overlay a scaled, alpha-blended image watermark	coverImage watermarkPosition watermarkSize watermarkOpacity watermarkX watermarkY
convert_video	Change container format, codec, and bitrate	videoFormat videoCodec videoBitrate
resize_video	Fit into a preset resolution/orientation frame with letterbox padding	resolutionPreset resizeVideoFormat
trim_video	Cut a segment starting at startTime for duration (re-encodes)	startTime duration
extract_audio	Extract the audio track (optionally transcoding), or strip audio entirely	extractAudioAction extractAudioFormat extractAudioBitrate
rotate_video	Rotate 90° CW/CCW, 180°, or mirror horizontally	rotation
grayscale_video	Named color-grade preset plus manual brightness/contrast/saturation trim	styleMode styleIntensity brightnessAdjust contrastAdjust saturationAdjust
burn_subtitles	Hardcode SRT/VTT/ASS subtitles into the video frame (irreversible)	subtitles

Audio

Operation	Description	Params
convert_audio	Transcode to a target format with optional loudness normalize / volume boost	audioFormat normalizeLoudness volumeBoostPercent outputSampleRate bitrate
trim_audio	Cut a segment from an audio file (start + duration)	startTime duration
audio_settings	Channel-layout change, full reverse, and/or fade in/out in one pass	audioChannelMode reverseAudioEnabled fadeInDuration fadeOutDuration
add_metadata	Write/remove ID3-style text metadata and embed/strip cover art, per container support	coverImage metadataArtist metadataTitle metadataReleaseDate metadataGenre removeCover removeAllMetadata
audio_speed	Change audio tempo (atempo-chained; same percent scale as video_speed)	speed (−100…100 %)

Image

Operation	Description	Params
resize_image	Resize/reformat a still image to a target aspect ratio and size	imageAspectRatio imageResizePreset imageCustomWidth imageCustomHeight imageOutputFormat
rotate_image	Rotate 90°/180° and/or flip horizontally/vertically	rotation flipHorizontal flipVertical
grayscale_image	Black-and-white via intensity-blended color mixer plus preset contrast/brightness	blackWhiteMode blackWhiteIntensity blackWhiteContrast blackWhiteBrightness
sharpness_image	Box blur and/or unsharp-mask sharpening	sharpenAmount blurStrength

Architecture

engine/
  opmodel.py      the model: Param (typed, validated) · Context · Operation
  ops/
    video.py      10 video operations
    audio.py       5 audio operations
    image.py       4 image operations
  operations.py   registry aggregator + run_operation (validate → probe → build → run)
  ffmpeg.py       process layer: binary resolution, -progress pipe:1 parsing,
                  bounded stderr tails, version capability probe, per-OS null device
  probe.py        ffprobe → MediaInfo (dimensions, duration, bitrates, audio presence)
cli.py            CLI face
server.py         MCP face (one typed tool per op, generated from the registry)
webserver.py      web face (stdlib http.server + SSE job streaming)
web/index.html    the entire frontend — one self-contained page, no build step
recon/            upstream recipe inventory + porting assessment

An operation is data plus one function:

Operation(
    id="video_to_gif", category="video",
    description="Video to animated GIF (two-pass palette) or WebP.",
    params=[Param("gifFpsPreset", "choice", 12, choices=[8, 10, 12, 15, 24, 25, 30, 50, 60]), ...],
    build=_build_gif,                 # Context -> [Pass, ...] (the ffmpeg invocations)
    output_ext=lambda p: "webp" if p.get("gifExportWebp") else "gif",
    needs_probe=False,                # True = run ffprobe first, results in ctx.info
)

run_operation validates params against the declared specs, probes the input if the op asks for it, calls build to get one or more ffmpeg Passes (multi-pass recipes like palette-gen GIF just return two), and executes them with live progress. Temp files created via ctx.tempfile() are cleaned up automatically.

To add an operation: write a _build_<op>(ctx) function and append an Operation(...) entry in the right engine/ops/*.py module. That's the whole job — the CLI subcommand, the typed MCP tool, and the web form all materialize from the entry.

Portability

• ffmpeg version probe — -fps_mode passthrough only exists on ffmpeg ≥ 5.0; engine/ffmpeg.py parses ffmpeg -version once and falls back to the legacy -vsync passthrough on older builds (verified end-to-end on 4.4.2; the modern-flag path is the same one the upstream recipes used against ffmpeg 6.x).
• Per-OS null device — /dev/null vs NUL chosen at runtime.
• Binary resolution — PATH lookup with FFMPEG_BIN / FFPROBE_BIN env overrides; no .exe assumptions.
• Machine-readable progress — -progress pipe:1 key-value stream instead of parsing locale/version-dependent stderr time= lines.
• Python — 3.9+, stdlib only (dataclasses, argparse, http.server, subprocess). The MCP face additionally follows fastmcp's Python requirement.

Provenance

The recipes were ported and adapted from media-by-outlaw2082 (GPL-3.0), an Electron GUI over ffmpeg — credit to Outlaw2082 for the original operation set and command recipes. This project reimplements them as a headless, dependency-free engine, keeping the recipes' behavior while fixing a few issues found during the port:

• rotate_video "Mirror" was exposed upstream but had no filter mapping (silent no-op); it now emits hflip.
• trim_audio / audio_settings relied on ffmpeg's default-encoder-by-extension guess; the codec is now set explicitly.
• audio_speed labeled its input "percent" but clamped a raw 0.5–2.0 factor; it now uses the same percent scale as video_speed with an atempo chain (no 2× ceiling).
• sharpness_image mapped its slider to unsharp amounts up to 20, outside ffmpeg's valid [-2, 5] range (errored on every build); remapped to 0–5.

The recon/ directory documents the original operation inventory and the porting assessment.

License

GPL-3.0 — inherited from the upstream project the recipes derive from, and kept gladly.