Music alignment

Such synchronization results form the basis for novel interfaces that allow users to access, search, and browse musical content in a convenient way.

To this end, techniques related to dynamic time warping (DTW) or hidden Markov models (HMMs) are used to compute an optimal alignment between two given feature sequences.

Similarly, the goal of score–audio alignment is to coordinate note events given in the score representation with audio data.

The goal is then to identify the currently played musical events depicted in the score with high accuracy and low latency.

[6][7] As opposed to classical DTW, such an online synchronization procedure inherently has a running time that is linear in the duration of the performed version.

However, as a main disadvantage, an online strategy is very sensitive to local tempo variations and deviations from the score - once the procedure is out of sync, it is very hard to recover and return to the right track.

First theme of Symphony No. 5 by Ludwig van Beethoven in a sheet music, audio, and piano-roll representation. The red bidirectional arrows indicate the aligned time positions of corresponding note events in the different representations.
Overview of the processing pipeline of a typical music alignment procedure.