Method of changing tempo and pitch of audio by digital signal processing

United States Patent [w]

Kondo

US005952596A [ii] Patent Number: [45] Date of Patent:

5,952,596 Sep. 14,1999

[54] METHOD OF CHANGING TEMPO AND PITCH OF AUDIO BY DIGITAL SIGNAL PROCESSING

[75] Inventor: Kazunobu Kondo, Hamamatsu, Japan

[73] Assignee: Yamaha Corporation, Hamamatsu, Japan

[21] Appl. No.: 09/153,529

[22] Filed: Sep. 15, 1998

[30] Foreign Application Priority Data

Sep. 22, 1997 [JP] Japan 9-256393

[51] Int. CI.6 G10H 1/40; G10H 7/04;

G10H 7/12

[52] U.S. CI 84/605; 84/607; 84/612;

84/652; 84/DIG. 12

[58] Field of Search 84/603-607, 612,

84/636, 652, 668, DIG. 12

[56] References Cited

U.S. PATENT DOCUMENTS

5,069,105 12/1991 Iba et al 84/605

5,131,042 7/1992 Oda 84/605 X

5,553,011 9/1996 Fujita 84/604 X

5,567,901 10/1996 Gibson et al 84/605 X

Primary Examiner—Stanley J. Witkowski

Attorney, Agent, or Firm—Pillsbury Madison & Sutro LLP

A pitch/tempo converting apparatus is constructed for concurrently changing a tempo and a pitch ol an audio signal according to tempo designation information and pitch designation information. In the apparatus, a memory section memorizes the audio signal composed ol original amplitude values sequentially sampled at original sampling points timed by an original sampling rate within an original frame period. A tempo converting section converts the original frame period into an actual frame period by varying a length ol the original frame period according to the tempo designation information so as to change the tempo ol the audio signal. A pitch converting section converts each ol the original sampling points into each ol actual sampling points by shifting each ol the original sampling points according to the pitch designation information so as to change the pitch ol the audio signal. An interpolating section calculates each ol actual amplitude values at each ol the actual sampling points by interpolating the original amplitude values sampled at original sampling points adjacent to the actual sampling point. A reading section sequentially reads the actual amplitude values by the original sampling rate during the actual frame period so as to reproduce a segment ol the audio signal within the actual frame period. A connecting section smoothly connects a series ol the segments reproduced by repetition ol the actual frame period to thereby continuously change the tempo and the pitch ol the audio signal.

8 Claims, 10 Drawing Sheets