Method for recognition of the start of a note in the case of percussion or plucked musical instruments
AssigneeYamaha Corporation
InventorAndreas Szalay
Life of this patent
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Abstract
A method is specified for recognition of the start of a note in the case of percussion or plucked musical instruments, in the case of which an envelope curve following function is formed from an audio signal, a comparison variable is formed from a current value of the envelope curve following function and a predecessor value corresponding to an earlier value, and the start of a note is defined at a point in time at which the comparison value exceeds a threshold value.
Claims28
A method for recognition of the start of a note in the case of percussion or plucked musical instruments, comprising the steps of:
- providing an audio signal from the musical instrument;
- forming an envelope curve following function from the audio signal,
- forming a comparison value from a current value of the envelope curve following function and a predecessor value corresponding to an earlier value of the envelope curve following function, and
- providing a start of a note signal at a point in time at which the comparison value exceeds a threshold value.
A method for recognition of the end of a note in the case of percussion or plucked musical instruments, comprising the steps of:
- providing a low-pass-filtered audio signal from the musical instrument;
- forming a filter envelope curve following function and a filter minimum value function from the low-pass-filtered audio signal, the forming step comprising forming a positive and a negative envelope curve following function and forming the filter envelope curve following function from the sum of the positive and negative envelope curve following functions, and
- providing an end of the note signal when the value of the filter envelope curve following function is less than the value of the filter minimum value function or a value proportional thereto at a point which is earlier in time by a predetermined interval.
Apparatus for recognition of the start of a note of a musical instrument producing a sound which is represented by an audio signal varying in time, said apparatus comprising:
- (a) means for generating an envelope curve following function for said audio signal;
- (b) step detector means for detecting an upward step having a certain magnitude in said envelope curve following function;
- (c) threshold generator means for generating a threshold;
- (d) trigger means for outputting a note-start signal, if said magnitude of said detected upward step exceeds said threshold.
Dependencies are inferred from the claim text.