When I posted my 787 takeoffs and landings video, I ran into a weird problem: When embedded here, the video would play in Safari at 4K (2160p), but when viewed on YouTube, the max resolution available was 1440p. After failing with web searches, I asked Twitter about it…
— Rob Griffiths (@rgriff) January 9, 2017
…but didn’t hear anything back. I pretty much gave up on the issue until today, when I stumbled across this article, which describes the exact problem I’m having. The summary of the article describes both the problem and the apparent cause:
What appears to be Google’s shift to the VP9 codec for delivering 4K video on the YouTube homepage is preventing Safari users from watching videos uploaded to the service since early December in full 4K resolution, but not from viewing webpage-embedded videos in the same resolution.
Note that this issue only affects videos uploaded after December 6, 2016:
Videos uploaded to the service prior to Dec. 6 in 4K resolution can still play back in full 4K resolution on Safari from the YouTube homepage.
I was curious about which macOS browsers this issue affects, so I thought I’d do a little experiment…