Why an MKV is harder than an MP4
MKV is a container. The video and audio tracks inside it can be anything, and a Chromecast only plays some of them. Google's supported media list names the containers and codecs a Cast receiver accepts, and MKV is not one of the standard containers. So a sender either has to repackage the tracks into a format the Chromecast takes, or convert them.
Before trying anything, play the file on the Mac with a local player and note the video and audio codecs. IINA's inspector and VLC's Window → Media Information both show them. If the picture or sound is already wrong on the Mac, no sender will fix it on the TV.
Three ways to send it
| Method | What it does | Where it falls short |
|---|---|---|
| Chrome tab | Open the file in Chrome with ⌘O, then Cast… from the Chrome menu (Google's steps) | Chrome has to play the MKV itself first. Many MKV files download instead of playing, or play without sound |
| VLC | Open the file, then Playback → Renderer and pick the Chromecast. VLC 3.0 added Chromecast output and can convert formats the receiver does not support (VideoLAN release notes) | Works one file at a time from the Mac. Results on macOS vary by version and file |
| Reelloft | Sends the file from a library on the Mac. When the Chromecast cannot play a file as it is, Reelloft remuxes or converts it while it plays | No subtitle or audio-track picker in version 0.2.1. The Mac has to stay awake while you watch |
All three need the Mac and the Chromecast on the same local network, and none of them is a screen mirror. Mirroring sends a copy of the whole screen; these send the file.
Casting with Reelloft
- Install Reelloft for macOS from the download page and open it.
- On first launch, select Choose folder and pick the folder with your MKV files. Reelloft scans it and builds the library.
- Open a title and select Play on TV. Pick the Chromecast from the list.
- Check the TV, not the Mac: picture, dialogue through the speakers you normally use, and one seek.
Every cast plays free for five minutes on an unlicensed copy, conversion included. That is enough to find out whether your Chromecast plays your files before you pay. A one-time $15 license removes the timer.
If the file needs conversion, leave Settings → Playback → Allow video conversion on. It is on by default. Turning it off blocks transcoding, and changing it needs an activated license.
If it does not work
| What you see | First check |
|---|---|
| The Chromecast is not in the list | Mac and Chromecast on the same network, not a guest network; no VPN on the Mac; Reelloft allowed under System Settings → Privacy & Security → Local Network |
| It starts, then stops at five minutes | That is the free preview limit on an unlicensed copy |
| Picture but no sound | The audio codec and the conversion path. See the MKV no-sound guide |
| You need a particular subtitle or language track | Reelloft 0.2.1 has no track picker. Use VLC for that file, or remux it with only the tracks you want |
For other receivers, such as DLNA TVs and classic AirPlay, see the computer-to-TV guide. If you also want to watch away from home, the Plex comparison covers that trade-off.