Lack of Opus support on macOS

Sad fact of the day: Safari on macOS still does not support Opus in .mp4 files.

You can test this in the browser’s developer console:

// streaming (Media Source Extensions)
MediaSource.isTypeSupported('audio/mp4; codecs="opus"');

// regular <audio>/<video> playback
document.createElement("audio").canPlayType('audio/mp4; codecs="opus"');

Chrome and Firefox say yes to both. Safari returns false for the first and "" (meaning “no”) for the second.