How does Youtube process videos?

[Kraizer]

Firstly, I'd like to apologize in advanced if this is the wrong section, it seemed proper.

Secondly, I'm curious as to how Youtube processes uploaded videos. For example, videos have different quality settings... 1080p, 340p, ect. I know you can control the quality for the most part via proper video editing and rendering, but how can you have different quality settings when you upload a video with a certain resolution and quality setting.

I'd also like to know why it is we can stream different quality settings in the middle of a video. Typically, the lower quality videos are a smaller size, and can be loaded more rapidly in comparison to something that is considered HD. Does Youtube, or other video hosting sites, create multiple versions of each video?

Answer away o.o If I'm not being clear, just lemme know!

 

[kenrivers]

This explains part of the process: http/youtube-global.blogspot.com/2011/02/speed-thrills-tackling-youtube-video.html
This link may provide further insight into how it is done: http/www.quora.com/Does-YouTube-store-multiple-resolution-copies-of-a-video-or-transcode-on-the-fly
It appears as though YouTube does, during the processing phase, create multiple versions of the video. I could be wrong but it appears that way to me. It won't make a lower resolution video a higher resolution video though. For example if the video is uploaded as 720p then that will be the highest resolution at which it will be viewable.

 

[USAFRet]

I'd also like to know why it is we can stream different quality settings in the middle of a video. Typically, the lower quality videos are a smaller size, and can be loaded more rapidly in comparison to something that is considered HD. Does Youtube, or other video hosting sites, create multiple versions of each video?

Multimedia servers can detect your connection speed, and adjust the bitrate and quality accordingly. Even when it changes midstream. Netflix does this as well.