MultiCast - Cast to Multiple Google Cast Devices

A Home Assistant custom integration that lets you cast media to multiple Google Cast / Chromecast devices simultaneously, with playback synchronization.

Features

• Cast to multiple devices at once — play the same media on all selected Cast devices simultaneously
• YouTube support — paste a YouTube URL and it plays on all devices via the YouTube Cast app
• Local media & cameras — browse and cast HA local media files and camera feeds
• Playback sync — periodic position correction keeps all devices aligned (configurable interval and thresholds)
• Playlist management — queue multiple items with single play, repeat, and shuffle modes
• Auto-retry — if a device fails to start, the integration retries for up to 2 minutes
• Auto-reconnect — disconnected devices are re-discovered every 5 minutes
• Overlapping groups — multiple groups can share devices; casting to one group transfers ownership of shared devices
• Full HA integration — exposed as a media_player entity with play, pause, stop, seek, volume, next/previous track

Installation

HACS (Recommended)

1. Open HACS in Home Assistant
2. Go to Integrations
3. Click the + button and search for MultiCast
4. Download and restart Home Assistant

Manual

1. Copy the custom_components/multicast folder to your HA config/custom_components/ directory
2. Restart Home Assistant

Setup

1. Go to Settings → Integrations → Add Integration
2. Search for MultiCast
3. Enter a name for your cast group
4. Select 2 or more Cast devices from the discovered list
5. Configure sync options (optional)

Services

Service	Description
multicast.play_media	Play a URL or YouTube link on the group
multicast.add_to_playlist	Add media URL to the playlist queue
multicast.clear_playlist	Clear the playlist
multicast.set_playlist_mode	Set mode: single, repeat, or shuffle
multicast.sync_now	Force immediate position sync

Example: Play YouTube on all devices

service: multicast.play_media
data:
  media_url: "https://www.youtube.com/watch?v=dQw4w9WgXcQ"

Example: Play local media

service: multicast.play_media
data:
  media_url: "/media/local/my_video.mp4"

Example: Target a specific group

service: multicast.play_media
data:
  media_url: "https://example.com/song.mp3"
  entity_id: "media_player.multicast_living_room"

Options

After setup, click Configure on the integration to adjust:

• Enable Sync — toggle position synchronization on/off
• Sync Interval — how often to check positions (5–60 seconds)
• Soft Sync Threshold — drift before seeking individual devices (0.5–5.0s)
• Hard Sync Threshold — drift before pause-seek-play all devices (2.0–30.0s)

How It Works

• Uses pychromecast to maintain connections to Cast devices
• Reads device states from HA's built-in Cast integration (reliable, no duplicate connections)
• Sends play/pause/seek/stop commands in parallel via asyncio.gather()
• Position sync uses median position as reference to correct drifting devices

License

MIT