Observed something odd on YouTube recently in Safari? It doesn’t play videos in 4K any longer. We may have the probable clarification as to why.
4K has figured out how to cement itself as the brilliant standard for video nowadays, however Apple is taking a stride back. If you open Safari at this moment, launch YouTube, watch a video, you’ll notice you can’t see anything in 4K. Any video uploaded in 4K maximizes at 1440p in Safari. Why does that happen? Well, the cause of that is straightforward, as pointed out by themcfly over at Reddit:
Upon further inspection, I discovered that Youtube stores different kinds of video on their servers, encoded either in VP9 or the older H264 codec. Safari has no VP9 support (at least in my version, still on Safari 9.1 / El Capitan) so it gets automatically served a H264 version from Youtube (you can verify codec by right clicking > stats for nerds). Chrome supports VP9 so gets served that version, but is far more hardware demanding to decode, so I installed another extension called H264fy that served me H264 version on Chrome. So I could use a fully functional Youtube Plus extension in Chrome without my MBP fans lifting off because of VP9.
Apple’s Safari browser on macOS and OS X does not support Google’s new VP9 codec for video. Google has set up 4K video in VP9 as standard, however lower resolutions get served up in H.264. If you use Chrome, the 4K video you are looking at is fueled by the VP9 codec, something which the Big G implemented support for in 2013 in Chrome. Apple then again, is yet to apply the codec in its browser.
There is a possibility the codec may in the long run advance toward Safari in a future upgrade, but we have no idea when that may happen. At the moment, if you want to watch anything in 4K, Chrome browser is your most solid option. It’s completely free to download and utilize.