Pitch control of memory addressing for changing speed of audio playback

• US 5,717,829 A
• Filed: 07/25/1995
• Issued: 02/10/1998
• Est. Priority Date: 07/28/1994
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Takagi, Satoshi
• Primary Examiner(s): MacDonald, Allen R.
• Assistant Examiner(s): Storm, Donald L.
• Application Number:
  US08/507,671
• Time in Patent Office: 931 Days
• Field of Search: 360/8, 395/2.16, 395/2.2, 395/2.76, 395/2, 395/2.1, 395/2.14, 395/2.22, 395/2.67, 395/2.77, 395/2.94, 395/2.95, 395/2.93, 395/2.92, 395/2.87, 395/2.26, 395/2.74 , 395/2.91, 395/2.25, 369/60, 381/54
• US Class Current: 704/503
• CPC Class Codes: G10H 2210/066 for pitch analysis as part of wider processing for musical purposes, e.g. transcription, musical performance evaluation; Pitch recognition, e.g. in polyphonic sounds; Estimation or use of missing fundamental
• CPC Class Codes: G10H 2250/631 Waveform resampling, i.e. sample rate conversion or sample depth conversion
• CPC Class Codes: G10H 3/125 Extracting or recognising the pitch or fundamental frequency of the picked up signal
• CPC Class Codes: G10H 7/02 in which amplitudes at successive sample points of a tone waveform are stored in one or more memories
• CPC Class Codes: G10L 21/01 Correction of time axis
• CPC Class Codes: G10L 25/90 Pitch determination of speech signals

Abstract

The playback speed of an audio signal is decreased or increased by repeatedly reproducing a preset audio signal domain or removing a domain of the audio signal. A memory stores the audio signal and an audio pitch is calculated from the audio signal readout from the memory. The audio pitch and information relating to power of the audio signal are used to produce a memory address sample set to be used in addressing the memory to reading out the audio signal at a desired playback speed. An address phase signal is fed back from a memory address controller to prevent over running or gaps from being formed in the audio signal reading out.

Claims

1. An audio signal processing apparatus comprising:

memory means for storing an input audio signal;

memory address control means;

pitch extracting means for calculating an audio pitch and power information from the audio signal read out from said memory means;

address phase management means receiving a zero pitch and a fixed pitch for use in outputting a memory address sample set providing an auto-correlation peak in a selected time duration of the audio signal in response to the audio pitch and the power information from said pitch extracting means and including

pitch detecting means for detecting whether the audio pitch from said pitch extracting means is a final pitch formed of a number of samples for use in memory address correction in response to a memory address from said memory address control means for outputting a second memory address sample set based upon the results of detection and

pitch selection means for selecting a final memory address sample set output from the address phase management means to the memory address control means using the second memory address sample set from said pitch detecting means; and

wherein said memory address control means calculates a memory address for said memory means using the memory address sample set from said address phase management means.

2. The audio signal processing apparatus as claimed in claim 1, wherein the auto-correlation peak is outputted as the power information from said pitch extracting means.