Global key extraction from classical music audio recordings based on the final chord

This paper presents a novel approach to global key extraction from audio recordings, restricted to the genre Classical only. Especially in this field of music, musical key is a significant information since many works include the key in their title. Our rule-based method relies on pre-extracted chroma features and puts special emphasis on the final chord of the piece to estimate the tonic note. To determine the mode, we analyze the chroma histogram over the complete piece and estimate the underlying diatonic scale. In both steps, we apply a multiplicative procedure to obtain high error robustness. This approach helps to minimize the amount of false tonic notes which is important for further key-related tonality analyses. The algorithm is evaluated on three different datasets containing mainly 18th and 19th century music for orchestra, piano, and mixed instruments. We reach accuracies up to 97% for correct full key (correct tonic note and mode) classification and up to 100% for correct tonic note classification.