No more laggy mirroring: New open-source tool casts web video to smart TVs at full quality

A new open-source command-line tool called Castor can cast arbitrary web video to a smart TV without the lag or resolution loss of screen mirroring, and without relying on Chromecast or AirPlay support at all.

The project has been built in Go and published on GitHub under the MIT license by developer "stupside." Castor extracts the actual video stream from a web page instead of mirroring a screen. It then transcodes the stream locally, and casts it directly. Castor accepts a web page URL, a direct stream link, or an IMDB/TMDB title ID.

According to the project's documentation, Castor launches headless Chrome with a randomized browser fingerprint to avoid bot detection, then monitors network traffic via the Chrome DevTools Protocol to locate the stream. Once found, the stream is transcoded with ffmpeg and cast in real time; an optional feature brings in auto-generated subtitles using a bundled whisper.cpp model.

Castor can target any TV supporting the DLNA/UPnP MediaRenderer standard. This covers most smart TVs from the past decade — Samsung, LG, Sony Bravia, Panasonic, Philips, Hisense, TCL, Vizio, and Sharp — plus players like Kodi, VLC, and Plex. Chromecast support does exist but is marked as experimental.

Installation on macOS is via Homebrew, requiring Chrome, ffmpeg, and ffprobe. A Docker image exists for Linux hosts, however, Docker Desktop on macOS/Windows can't reach local devices due to its networking setup. Setup needs only a config file with the device's name and content sources; a TMDB key is optional, but it enables an interactive terminal browser for titles by poster and metadata.

Castor is available now at github.com/stupside/castor, currently at version 1.4.1 with 89 stars as of writing. The developer states Castor hosts no content itself, and that compliance with applicable laws and site terms is the user's responsibility.