how does youtube know that you uploaded the same video? [closed]

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Closed 12 years ago.

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do they store the hashes of the videos and then compare them? how do they know that you had already uploaded that video? there are plenty of videos on you tube that have the same file name and file size.

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They likely do hashes. But since Google acquired YouTube, there's a lot more intelligence in their code. Google and others have been working on creating "digital fingerprints" for media like movies, where defining characteristics become part of the same result even if the file is mildly tampered with. Because this is an ongoing race between (loosely speaking) "pirates" and "the Powers That Be," there's research ongoing on both sides of the fence, and the algorithms involved are likely to be kept as industry secrets.

(a good excuse for me to only give you this vague, hand-waving explanation instead of some useful facts).