Hi @OkanAkyuz thank you for asking! 😊
You can upload 4k videos but keep in mind that now, Udemy only reprocesses the file up to 720p. Students have the ability to view videos in 1080p, but courses in the Marketplace are not automatically enabled for adaptive streaming, you can contact our support team in order to get it enabled and we’ll be happy to help.
Let us know if you have additional questions.
Best regards,
Bessy
Udemy Community Moderator
