Abstract text
Methods, systems, and devices are described for automatically converting audio input signal data into musical score representation data. Embodiments of the invention identify a change in frequency information from the audio signal that exceeds a first threshold value; identify a change in amplitude information from the audio signal that exceeds a second threshold value; and generate a note onset event, each note onset
event representing a time location in the audio signal of at least one of an identified change in the frequency information that exceeds the first threshold value or an identified change in the amplitude information that exceeds the second threshold value. The generation of note onset events and other information from the audio input signal may be used to extract note pitch, note value, tempo, meter, key, instrumentation,
and other score representation information.Claims
1. A system for generating score data from an audio signal, the system comprising:an audio receiver operable to process the audio signal; anda note identification unit operable to receive the processed audio signal and generate a note onset event associated with a time location in the processed audio signal in response to at least one of:identifying a change in frequency exceeding a first threshold value; andidentifying a change in amplitude exceeding a second threshold value.
2. The system of claim 1, wherein the note identification unit comprises:a signal processor comprising:a frequency detector unit operable to identify the change in frequency of the audio signal exceeding the first threshold value, and an amplitude detector unit operable to identify a change in amplitude of the audio signal exceeding the second threshold value; anda note processor that includes a note onset event generator that is in operative communication with the frequency detector unit and the amplitude detector unit and is operable to generate the note onset event.
3. The system of claim 2, wherein the note processor further comprises:a first envelope generator operable to
generate a first envelope signal in accordance with magnitude of the processed audio signal;a second envelope generator operable to generate a second envelope signal in accordance with an average power value of the first envelope signal; anda control signal generator operable to generate a control signal responsive to a change in the first envelope signal from a first direction to a second direction such that the change extends for a duration greater than a predetermined control time;wherein the amplitude detector unit identifies the change in magnitude of the audio signal exceeding the second threshold value in response to magnitude of the control signal having a value greater than a magnitude of the second envelope signal.
4. The system of claim 3, wherein generating a note onset event includes indicating a time stamp value of the audio input signal corresponding to the note onset event.
5. The system of claim 4, wherein the first envelope function comprises a function that approximates the magnitude of the audio input signal at each time stamp value and the second envelope function comprises a function that approximates average power of the first envelope function over
an averaging interval.
6. The system of claim 5, wherein the control signal value at each time stamp value is set equal to the greatest magnitude value of the first envelope function at a preceding time stamp value and, in response to a difference in value between the first envelope function value at a time stamp value and the first envelope function value
at a preceding time stamp value that is different in value for a time interval greater than a third threshold value, the control signal value at the time stamp value is changed to a negative value in comparison to the preceding control signal value.
7. The system of claim 5, wherein generating a note onset event further includes adjusting the averaging inter
