The biggest hurdle for a real world system could be creating the audio database itself.

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The Gracenote technology works by "listening" to a few seconds of a song and matching it to its unique audio fingerprint in the Gracenote database.

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But the tests used a database of just 24 hours of audio.

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Does it contain a significant amount of unstructured data from video or audio or can it be put into a relational database easily?

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Users connect their audio source to the player via analog audio input, and the player compares 15 seconds of waveform data with its internal "FingerPrints" database, matching the song up with its corresponding information from MusicID.

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