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CastMirror 1.0.0 for Linux

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@github-actions github-actions released this 30 Sep 17:36
· 9 commits to master since this release
linux-v1.0.0
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CastMirror 1.0.0 for Linux is the first stable release of the GTK 4 app and the command-line tool. It mirrors a display or a single window, with sound, to a Chromecast, Google TV or Cast-enabled TV on the same network, without Chrome.

The Windows app is the main product and has its own release (windows-v1.0.0). The Linux build uses the same castcore engine, so it gets the same protocol, security and reliability fixes, but the desktop capture, audio and GUI layers on Linux are separate code, and they get less testing.

Download

File Use it for
castmirror_1.0.0_x86_64.deb Debian, Ubuntu and derivatives.
castmirror_1.0.0_x86_64.rpm Fedora and other RPM distributions. Built best-effort on an Ubuntu runner, so treat it as less tested than the .deb.
SHA256SUMS Checksums for the packages. 
sudo apt install ./castmirror_1.0.0_x86_64.deb
castmirror-gui              # GTK 4 app
castmirror --device 192.168.0.164 --display 0 --preset High

Your TV and PC must be on the same subnet. Control traffic goes to TCP 8009 on the TV, and media goes over UDP to the port the TV returns. scripts/setup_firewall.sh opens what is needed.

What you get

  • Discovery over mDNS, a subnet scan for networks that block it, and manual IP entry.
  • Whole-display capture on X11 (XRandR with MIT-SHM), single-window capture on X11 including windows that are covered (XComposite), and Wayland capture through the xdg-desktop-portal ScreenCast picker over PipeWire.
  • System audio from the PulseAudio or PipeWire default sink monitor, encoded as Opus.
  • H.264 through VAAPI when a GPU is available, with an automatic fall back to libx264.
  • Six quality presets, live bitrate changes, freeze and mute controls, an adaptive bitrate ladder, and reconnect after a dropped connection.
  • A GTK 4 and libadwaita app with a live view of frame rate, bitrate, round-trip time and loss, plus a self-test wizard, and a CLI for scripting.

Fixed since the pre-release builds

These come from the shared engine and apply on Linux too:

  • The per-session encryption key and IV mask were written to the log. They are now redacted everywhere.
  • Starting and stopping a cast at the same moment could free the session while it was still connecting. Stop now cancels an in-flight start.
  • A state callback could deadlock the whole connection attempt.
  • A TV that answered error to the offer made the app wait out the full timeout. It now fails at once.
  • Pressing Back on the TV ended the app on the receiver and CastMirror relaunched it for 30 seconds. It now ends the cast.
  • Frame ids advanced when the encoder produced nothing, so the TV stalled until the next key frame.
  • Discovery listed phantom devices from unrelated mDNS traffic, and a TV that was switched off stayed in the list forever.
  • Adaptive-bitrate and reconnect state were shared between threads without locks.
  • Config saves could interleave and corrupt the file.
  • The Game and Cinema presets did nothing different from Auto. They now set their own delay and bitrate.
  • The HTTP/CAF fallback server is gone. It bound every interface without authentication.
  • Colours are converted and tagged as BT.709, which is what TVs decode HD video as.

The complete list is in the changelog.

How it was tested

  • The full unit and integration suite (TLS, offer and answer, and media streaming against a simulated receiver) runs in CI on Ubuntu Release, ASan and UBSan, TSan, and a Fedora container.
  • The RTCP and mDNS parsers run under libFuzzer in CI.

Known limits

  • Not yet verified on a physical-device matrix. The device rows in docs/DEVICE_MATRIX.md predate this release and were not re-measured for it.
  • The maintainers' hands-on testing this cycle was on Windows. The GTK app, the Wayland portal path and the VAAPI encoder were built and unit-tested in CI but not exercised on a live desktop for this release. Bug reports with the output of the in-app Logs tab are welcome.
  • This .deb is built without the system tray icon. The tray needs the ayatana-appindicator-glib library, which Ubuntu 24.04, the build image, does not package. A build from source on a distribution that has the library gets the tray.
  • Cast keeps a playout buffer, so expect about 150 to 400 ms of delay depending on the preset.
  • Cast receivers accept H.264 and VP8 for mirroring, so there is no HEVC or VP9 option.

Licence

CastMirror's own source is Apache-2.0. The binaries link FFmpeg with libx264, which is GPL, so the package as a whole is distributed under the GPL. The details and the source offer are in NOTICE and THIRD-PARTY-LICENSES.txt, installed under /usr/share/doc/castmirror.

CastMirror is not affiliated with Google. Chromecast, Google Cast and Google TV are trademarks of Google LLC.

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