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Ermittelt automatisch Akkorde zu beliebigen Songs und zeigt sie live an. Funktioniert erstaunlich gut, auch wenn's bei reiner Sprache erstmal verrückt spielt.

Mit einiger Open Source Software gebaut. Aus der About-Page:

Technology behind Chordify
We’ve done our best to make our website simple and easy to use, even though there is some complex technology behind Chordify. Our website is built using up to the minute web development techniques, like HTML5 audio etc.

Behind the scenes, we use the sonic annotator for extraction of audio features. More specifically, we extract the NNLS chroma features developed by Matthias Mauch using the Chordino VAMP plugin. These features describe the tonal content of a piece of music. Next, a Haskell program HarmTrace then takes these features and computes the chords. For this to happen, HarmTrace uses a model of Western tonal harmony to aid in the chord selection. At beat positions where the audio matches a particular chord well, this chord is used in the final transcription. However, where there is uncertainty about the sounding chords at a specific position in the song, the HarmTrace harmony model will select the correct chords based on the rules of tonal harmony.