Pitch control of memory addressing for changing speed of audio playback

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.