Method and apparatus for changing the timbre and/or pitch of audio signals

• US 6,046,395 A
• Filed: 01/14/1997
• Issued: 04/04/2000
• Est. Priority Date: 01/18/1995
• Status: Expired due to Fees

• Current Assignee: IVL Audio Inc.
• Original Assignee: IVL Technologies, Ltd.
• Inventors: Jubien, Christopher Michael, Roden, Brian John, Gibson, Brian Charles
• Primary Examiner(s): Donels, Jeffrey W.
• Application Number:
  US08/783,643
• Time in Patent Office: 1,176 Days
• Field of Search: 84/603-605, 84/619, 84/622, 84/659, 381/49, 395/2.14
• US Class Current: 84/603
• CPC Class Codes: G10H 1/20 for transposition
• CPC Class Codes: G10H 1/366 with means for modifying or correcting the external signal, e.g. pitch correction, reverberation, changing a singer's voice
• CPC Class Codes: G10H 2240/311 MIDI transmission G10H2240/056 takes precedence
• CPC Class Codes: G10H 2250/285 Hann or Hanning window
• CPC Class Codes: G10H 2250/631 Waveform resampling, i.e. sample rate conversion or sample depth conversion waveform decimation G10H2250/611
• CPC Class Codes: G10H 3/125 Extracting or recognising the pitch or fundamental frequency of the picked up signal

Abstract

A method for shifting the timbre and/or pitch of an input signal samples the input signal at a first rate and stores the samples in a memory buffer. A digital signal processor resamples the stored input signal at a rate that differs from the first rate at which the input note is originally sampled and stores the resampled input signal in a second memory buffer. A pitch shifter shifts the pitch of the input signal by periodically scaling the resampled input signal by a window function to create an output signal. The rate at which the resampled data is replicated by the window function determines the pitch of the output signal.

Claims

1. A method of creating a timbre shifted output signal from an input signal, comprising the steps of:

acquiring a digital representation of said input signal;

scaling in time said digital representation;

extracting a segment of said scaled digital representation;

replicating said extracted segment at a rate equal to a fundamental frequency of said output signal to thereby produce said timbre shifted ou signal.

2. The method of claim 1 wherein said digital representation is of a portion of said input signal and wherein the method includes the additional step of iterating the steps of claim 1 in relation to successive other portions of said input signal.

3. A method of creating a timbre shifted output signal from an input signal, comprising the steps of:

acquiring a digital representation of said input signal;

extracting a segment of said digital representation;

replicating said extracted segment;

scaling in time said replicated segments to thereby produce said timbre shifted output signal.

4. The method of claim 3 wherein said digital representation is of a portion of said input signal and wherein the method includes the additional step of iterating the steps of claim 3 in relation to successive other portions of said input signal.

5. A method of creating a timbre shifted output signal from an input signal, comprising the steps of:

acquiring a digital representation of said input signal;

extracting a segment of said digital representation representative of a predetermined number of periods of said input signal;

scaling in time said extracted segment; and

replicating said scaled extracted segment to thereby produce said timbre shifted output signal.

6. The method of claim 5 wherein said digital representation is of a portion of said input signal and wherein the method includes the additional step of iterating the steps of claim 5 in relation to successive other portions of said input signal.