Midi-code generating device

• US 5,367,117 A
• Filed: 08/29/1991
• Issued: 11/22/1994
• Est. Priority Date: 11/28/1990
• Status: Expired due to Fees

• Current Assignee: Yamaha Corporation
• Original Assignee: Yamaha Corporation
• Inventors: Kikuchi, Takeshi
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): Sircus, Brian
• Application Number:
  US07/752,034
• Time in Patent Office: 1,181 Days
• Field of Search: 84/603, 84/645, 84/600, 84/615-617, 84/647, 84/653, 84/654, 84/661, 84/681, 84/700, 84/736, 84/453, 84/454, 84/18, 84/655, 84/682, 84/DIG. 7, 84/1 8, 381/83, 381/93, 324/77 C, 324/78 F, 324/78 D
• US Class Current: 84/603
• CPC Class Codes: G10H 1/0066 using a MIDI interface

Abstract

A MIDI-code generating device utilizing a musical instrument for producing a plurality of musical tones which comprise a fundamental tone and a harmonic tone corresponding to the fundamental tone, the fundamental and harmonic tones being discrete frequencies and having different envelope wave-forms, includes a microphone for converting a produced musical tone from the musical instrument into an electrical audio signal, an A/D converter for converting the electrical audio signal into digital signal of wave-form data, a group of band-pass filters for extracting wave-form data having frequency component respectively corresponding to each of the fundamental tones, from wave-form data outputted by the A/D converter, an envelope detection circuit for detecting envelope data of wave-form data extracted by the group of band-pass filters, a memory for storing reference envelope data of the fundamental tone corresponding to the envelope wave-form of each fundamental tone of the musical tones produced by the musical instrument, a fundamental tone decision circuit for comparing envelope data detected by the envelope detection circuit with fundamental tone envelope data stored in the memory, and for deciding on a produced fundamental tone when the musical tone is produced by the musical instrument, and a coding circuit for generating a MIDI-code according to a result of a decision of the fundamental tone decision circuit and the detected envelope data.

Claims

1. A MIDI-code generating device for generating a MIDI-code corresponding to sound produced by a musical instrument, comprising:

a musical instrument for producing a plurality of musical tones which comprise a fundamental tone and a harmonic tone corresponding to the fundamental tone, the fundamental and harmonic tones being discrete frequencies and having different envelope wave-forms;

conversion means for converting a produced musical tone from the musical instrument into an electrical audio signal and converting the electrical audio signal into a digital signal having wave-form data;

a group of band-pass filters for extracting wave-form data having frequency components respectively corresponding to each of the fundamental tones, from wave-form data outputted by the conversion means;

envelope detection means for detecting envelope data of wave-form data extracted by the group of band-pass filters;

fundamental tone envelope storage means for storing reference envelope data of the fundamental tone corresponding to the envelope wave-form of each fundamental tone of the musical tones produced by the musical instrument;

fundamental tone decision means for comparing envelope data detected by the envelope detection means with reference fundamental tone envelope data stored in the fundamental tone envelope means to determine a produced fundamental tone when the musical tone is produced by the musical tone producing means; and

coding means for generating a MIDI-code according to a result of a decision of the fundamental tone decision means and the envelope data detected by the envelope detection means, the MIDI-code corresponding to the musical tones produced by the musical instrument.

2. A MIDI-code generating device according to claim 1 wherein said band-pass filter group comprises a processor of stored program type executing real time digital signal processing and forming a plurality of passband characteristics.

3. A MIDI-code generating device according to claim 1 wherein said fundamental tone envelope storage means stores wave-form data of each fundamental tone envelope differentiated by a differential filter.

4. A MIDI-code generating device according to claim 1 wherein said fundamental tone decision means compares the detected envelope data with the stored envelope data by cross correlation, and determines production of the fundamental tone when a comparison result is over a predetermined value.

5. A method for detecting a fundamental tone comprising the steps of:

operating a musical instrument to produce a plurality of musical tones which comprise a fundamental tone and a harmonic tone corresponding to the fundamental tone, the fundamental and harmonic tones being discrete frequencies and having different envelope wave-forms;

collecting a produced musical tone as an analog audio signal;

converting the analog audio signal into a digital signal having wave-form data;

extracting wave-form data having frequency components respectively corresponding to each of the fundamental tones, from the wave-form data;

detecting envelope data of the extracted wave-form data;

storing reference envelope data of the fundamental tone corresponding to the envelope wave-form of each fundamental tone of the musical tones;

comparing the detected envelope data with the stored reference envelope data of the fundamental tone; and

determining production of the fundamental tone according to a result of the comparison.

6. A MIDI-code generating device according to claim 5 further comprising the step of:

generating a MIDI-code according to a result of the determining of the production of the fundamental tone and the detected envelope data.