Better and Cheaper Than IPTV

Smart TVs won't cast arbitrary web video, and screen mirroring is laggy and drops resolution. Castor casts the real stream instead, at full quality, from your terminal.

I built it because I couldn't cast web video from my laptop to my TV: no Chromecast, no AirPlay.

Point it at any web page and it finds the video, extracts the stream, transcodes it, and casts in real time to your TV. It even burns in auto-generated subtitles. It also takes a direct stream URL or an IMDB/TMDB id.

Important

Castor is a proof of concept, not a piracy tool. It's a personal experiment in headless-browser stream extraction, real-time transcoding, and DLNA casting, published to share the engineering. Castor hosts no content, ships no catalog, and bundles no sources of its own. What you point it at, and whether you have the right to cast it, is entirely your responsibility. See Purpose and disclaimer.

Run castor cast to browse titles and cast, without leaving the terminal.

Note

How extraction works

Castor launches headless Chrome and watches network traffic over the Chrome DevTools Protocol to find the video stream the page loads. It then runs a short action pipeline: click the page, navigate into the largest iframe, and click again as a fallback.

Installation

The recommended way to run Castor is the native binary. It runs directly on your machine, so it shares your TV's network, which device discovery needs. It requires Chrome/Chromium (headless extraction), ffmpeg (transcoding), and ffprobe (format detection) on your PATH. Docker is an optional alternative that bundles all three, but only works from a Linux host.

Homebrew (macOS)

brew install --cask stupside/tap/castor

See Quick start to create the one-time config.yaml (which TV, which sources). After that, casting is a single command:

castor cast movie tt12300742

From source

Needs Go 1.26+ and cmake (the whisper.cpp bindings are cgo and link a locally built libwhisper.a):

git clone --recurse-submodules https://github.com/stupside/castor.git
cd castor
make          # builds libwhisper.a, then the castor binary

go install won't work: the vendored whisper.cpp bindings come in through a local replace and need that prebuilt static lib.

Docker (optional)

Warning

Docker can only reach your TV from a Linux host on the same LAN. Discovery is SSDP multicast and the TV streams back from Castor's replay server, and neither survives Docker's bridge network, so --network host is required. But on Docker Desktop (macOS/Windows) --network host is a silent no-op: the container lands on Docker Desktop's internal VM subnet (e.g. 192.168.65.x), never your real LAN, so scan finds nothing and cast fails with device "…" (type dlna) not found even though the TV is up. No docker run flag fixes this. On macOS/Windows, run the native binary instead. Or point Docker at a Linux VM bridged onto your LAN (e.g. Lima + socket_vmnet), which is the only way a container gets a real address on your network.

On a Linux box or NAS on the same network as the TV, the prebuilt ghcr.io/stupside/castor image bundles Chrome, ffmpeg and ffprobe so you don't install them by hand:

# Discover devices (no config required)
docker run --rm --network host ghcr.io/stupside/castor:latest scan

# Cast a movie by id, mounting config.yaml and a persistent model cache
docker run --rm --network host \
  -v "$PWD/config.yaml:/config.yaml" \
  -v castor-cache:/root/.cache \
  ghcr.io/stupside/castor:latest \
  cast movie tt12300742

The -v "$PWD/config.yaml:/config.yaml" mount is what makes this work: the container reads your device and sources from config.yaml at /config.yaml, so run every command from the directory holding it. The castor-cache volume keeps the auto-downloaded whisper models (~75 MB) between runs; swap :latest for any release tag to pin a version.

Supported devices

DLNA / UPnP

Any TV implementing the DLNA/UPnP MediaRenderer:1 profile works, which covers virtually every smart TV sold in the last decade: Samsung (tested), LG, Sony Bravia, Panasonic Viera, Philips, Hisense, TCL, VIZIO, Sharp. Networked players like Kodi, VLC, and Plex also work.

Run castor scan to discover devices on your network.

Chromecast

Warning

Experimental: implemented but untested. Contributions welcome.

Quick start

Castor requires a config.yaml in the current directory (or pass --config). Everything mechanical ships with working defaults, so a minimal file only has to say which device to cast to and which sources to cast from. Like a media server, Castor bundles no sources of its own: you supply your own, and they must be sites you are authorized to use. A TMDB API key is optional, needed only for the interactive browser.

# 1. Find your TV's exact name
castor scan

Create config.yaml with that name:

device:
  name: "Living Room TV"   # exact name from `castor scan`
  type: dlna

sources:
  # Castor ships none. Add your own source (a site you are authorized to use).
  - proxies: ["https://your-source.example"]
    templates:
      movie: "/embed/movie/{itemID}"
      episode: "/embed/tv/{itemID}/{season}-{episode}"

# tmdb:
#   api_key: "<KEY>"   # optional, only for the `castor cast` browser; free from https://www.themoviedb.org/settings/api

That's all you need to cast by id:

# 2. Cast a movie straight from an IMDB/TMDB id, resolved through your sources
castor cast movie tt12300742

Note

Sources can change. cast movie resolves the id against the proxies you set in config.yaml. These are external sites, so one can go offline or move without notice. If a cast stops resolving, update that entry in the proxies list or add another.

Prefer to browse? Add a tmdb.api_key and run castor cast for an interactive TUI: pick a device, find a title, and cast it.

Usage

# Interactive browser: pick a title and cast (needs a tmdb.api_key)
castor cast

# Cast whatever video is playing on a web page
castor cast player https://example.com/watch/some-video

# Cast by IMDB/TMDB id, using the sources in your config
castor cast movie   tt33028778
castor cast episode tt2699128 --season 1 --episode 3

# Cast a raw stream URL directly
castor cast url https://example.com/stream.m3u8

# Useful flags
castor cast movie --dry-run tt33028778   # print found URLs without casting
castor --debug cast player https://...   # verbose logging
castor scan                              # discover devices on the network
castor info                              # version / build info

Configuration

Quick start covers the required keys. Beyond those, everything mechanical (timeouts, probing, capture, transcoding, Chrome discovery) ships with working defaults. Override any of it in config.yaml, point at a different file with --config, drop secrets like your TMDB key into a git-ignored sibling config.local.yaml (it overlays config.yaml), or set CASTOR_SECTION__FIELD environment variables.

The one opt-in worth calling out is auto-generated subtitles, burned into the video:

whisper:
  enable: true             # off by default
  # language: "fr"         # default: English
  # model_path: ""         # default: ggml-tiny.en (~75 MB, auto-downloaded)

Purpose and disclaimer

• It hosts nothing. Castor ships no video, no catalog, and no sources of its own. It's a general caster that sends a stream you already have to a TV on your network, the same job a Chromecast does.
• The example sources are placeholders. The sites shown in the sample config.yaml are illustrative. Which sites you point Castor at, and whether that respects their terms of use and your local law, is entirely your responsibility.
• Only cast content you are authorized to access. Do not use Castor to infringe copyright or to bypass access controls on content you have no right to view.

The author does not endorse or condone piracy, and provides Castor as-is for lawful, personal, and educational use.

Contributing

See CONTRIBUTING.md.