For user who try stream a 4K YouTube video on Chrome or Firefox, it plays smoothly with no problems. However, you will find that you have no luck to view them on Safari. The fact is that YouTube appears to be storing many new 4K with the more efficient VP9 codec, which is not supported by Safari, which explains why recently uploaded 4K videos are only able to be viewed in up to 1440p in Safari. How to fix the new YouTube 4K safari playback problems, find solution in below article.
Fix new 4K VP9 YouTube video not playing on Safari
Solution 1: Play 4K VP9 YouTube video on Chrome or Firefox
Solution 2 - Check 4K YouTube Video
Although there are a lot of 4K video on YouTube, however, most of them are not authentic 4K video but are just titled with 4K Ultra HD. Chances are that the person who loads 4K video but forgets to activate "Upload HD video" on YouTube. So the uploaded so-called 4K video he thought it's in 2160p might be automatically downgrade to 2K 1440p during the uploading procedure. So it's no strange that you can't find the 4K option in Safari YouTube.
Fix old 4K 60fps YouTube video not playing on Safari
For Safari users who try to stream old 4K 60fps YouTube video encoded with H.264 codec also complain that they fail to play the video on Safari. The condition is that they have no problem to play 4K YouTube video on Safari at 24fps, but fail at 60fps. While Google Chrome and Safari can do that quite well. We can concluded the issue is caused due not the incompatible frame rate but not about the codec. In this case, just have a try at the following solutions.
Compress YouTube 4K 60fps to YouTube 4K 24fps
If you insist on to viewing 4K YouTube 60fps video on Safari, the most effective solution for you is lowering the frame rate from 60fps to 24fps. Here, you can easily complete the job with Pavtube Video Converter Ultimate (best video converter review), which allows you to adjust the output frame rate to Safari playable 4K YouTube 24fps video in the program's profile parameters window. What's worthy mentioning here is that you can perform the frame rate adjusting process without changing the original video codec by using the program to out the same H.264 codec.
How to Fix Safari Won't Play Old 4K 60fps YouTube Video by Changing Frame Rate?
Step 1: Load YouTube 4K video into the program.
Run the program on your Mac computer and click "File" > "Add Video/Audio" or "Add from folder" to add 4K 60fps H.264 YouTube video into the program.
Step 2: Output the same video codec as original YouTube 4K video.
From the pull down menu of "Format" , you can select the output the same video codec used by original 4K YouTube video, here, we choose "H.264 High Profile Video(*.mp4)" under "Common Video" main category.
Step 3: Adjust output video frame rate.
Click "Settings" to open "Profile Settings" window, here, you can change the output frame rate to
Safari playable 24fps from "Frame Rate(fps)" drop-down list.
Step 4: Start the final conversion process.
After all setting is completed, click right-bottom "Convert" button to begin the 4K H.264 YouTube 60fps to 4K H.264 YouTube 24 fps conversion process.
When the conversion is completed, you will have no problem to play 4K H.264 YouTube video on Safari any more..