Abstract: Among other things, techniques and systems are disclosed for detecting musical structures, such as downbeats. In one aspect, a method performed by a data processing device includes receiving an input audio signal. The method includes detecting a meter in the received audio signal. Detecting the meter includes generating an envelope of the received audio signal; generating an autocorrelation phase matrix having a two-dimensional array based on the generated envelope to identify a dominant periodicity in the received audio signal; and filtering both dimensions of the generated autocorrelation phase matrix to enhance peaks in the two-dimensional array. The meter represents a time signature of the input audio signal having multiple beats. Additionally, the method includes identifying a downbeat as a first beat in the detected meter.

Abstract: Among other things, techniques and systems are disclosed for detecting onsets. On a device, an audio signal is pre-processed in temporal domain. The pre-processed audio signal is smoothed on the device. A predetermined quantity of peaks is selectively identified in the pre-processed and smoothed audio signal based on a size of a sample window applied to the pre-processed and smoothed audio signal.

Abstract: Among other things, techniques and systems are disclosed for detecting musical structures, such as downbeats. In one aspect, a method performed by a data processing device includes receiving an input audio signal. The method includes detecting a meter in the received audio signal. Detecting the meter includes generating an envelope of the received audio signal; generating an autocorrelation phase matrix having a two-dimensional array based on the generated envelope to identify a dominant periodicity in the received audio signal; and filtering both dimensions of the generated autocorrelation phase matrix to enhance peaks in the two-dimensional array. The meter represents a time signature of the input audio signal having multiple beats. Additionally, the method includes identifying a downbeat as a first beat in the detected meter.

Abstract: Among other things, techniques and systems are disclosed for detecting onsets. On a device, an audio signal is pre-processed in temporal domain. The pre-processed audio signal is smoothed on the device. A predetermined quantity of peaks is selectively identified in the pre-processed and smoothed audio signal based on a size of a sample window applied to the pre-processed and smoothed audio signal.