Youtube typically uses for 1080p videos H.264 and VP9.
In theory VP9 was expected to be a successor to H.264 but frankly it failed to live to the expectations especially in videos which aren't starved for bitrate. Additionally mature encoders like x264 didn't help the VP9 cause.
I want do download some videos from youtube but I'm talking about more than one. Those videos are available in both VP9 and H.264. So obviously I don't want to download two videos from youtube (one H.264, one VP9) and then compare the quality of those two.
Can I make some assumptions which will be good for most videos? Can I assume than at a intermediate resolution (1080p) both should be equal or should assume that the VP9 should be superior in terms of image quality?
Best Answer
Considering that YouTube will only encode popular videos in VP9 (with a very loose definition of "popular") and keep all those holiday travel videos in h.264, and only offers 4K in VP9, I'd say YouTube thinks that VP9 has storage, bandwidth and/or quality advantages over h.264.
So VP9 probably is the better choice, usually.
Also, just for the record: Note that downloading videos is a violation of YouTube's TOS.