[RDeckard]

I am curious: is YouTube going to re-encode all existing content with VP9? If so, I am wondering if they do anything special to preserve as much quality as possible. Are there any techniques to do that? (For example, certain JPEG transforms such as rotation can be applied with zero quality loss.)

[manigandham]

Youtube keeps all the original source files so there's no quality loss going from one encoding to another, if that's what you were referring to.

[RDeckard]

Do they really - do you have a source on that? (no pun intended)

[jsalit]

Yep, there's mention of it on an old blog post [1], but you can verify for yourself on the Enhancements page when editing any video - there's a "Revert to original" button.

[1] - http://youtube-global.blogspot.com/2011/09/edit-your-videos-...

[TazeTSchnitzel]

They don't need special sauce. YouTube retains the original uploaded video to enable reëncoding.