Audio compression method and apparatus

• US 20030220801A1
• Filed: 05/22/2002
• Published: 11/27/2003
• Est. Priority Date: 05/22/2002
• Status: Abandoned Application

• Current Assignee: Thomas E. Spurrier
• Original Assignee: Thomas E. Spurrier
• Inventors: Spurrier, Thomas E.
• Application Number:
  US10/151,815
• Publication Number:
  US 20030220801A1
• Time in Patent Office: Days
• US Class Current: 704/503
• CPC Class Codes: G10L 19/00 Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis in musical instruments G10H

Abstract

A method and system for communicating audio signals at a low bit rate and yet retaining significant representation of the original signal is disclosed in this patent This method interweaves both compressed audio and a messaging protocol into a data stream that can be transmitted over any digital communication medium thus eliminating the need for higher levels of protocol overhead. A digitally sampled wave (from a microphone) is accumulated in a memory and subsequently compressed by finding a maximum value (peak) followed by a minimum value (valley) and recording the count of the number of samples between the peak and valley. A digital band pass filter (BPF), such as an IIR or FIR, is used on the input raw wave to smooth and eliminate noise thus increasing compressibility. A protocol consisting of commands and information are interwoven with the compressed signal. This interwoven protocol data is de-commutated prior to regeneration of the signal. The output of the audio compressor and protocol commutator is connected to a transmission channel that provides a circuit path to the receiver. A wave is regenerated by connecting a half wave spline containing a point for each sample between a peak and valley. A cosine function is used to regenerate the spline. The regenerated signal is placed into a memory that subsequently transferred into a digital to analog converter that is connected to an audio sensor (earphone or speaker).

Claims

1. An audio compression method for transmitting lossey real-time audio signals over a communication network, comprising the steps of:

(a) sampling at least one audio signal,

(b) converting said at least one audio signal,

(c) storing said converted signals of step (b) in at least one register as a random access memory location,

(d) filtering said stored data signals from said at least one register of step (c),

(e) compressing said filtered data signals wherein said compression step further includes the steps of;

(e1) determining a first derivative of said filtered data signal, and regenerating compressed data signals,

(e2) detecting at least one local peak and valley of the filtered data signal over a specified interval,

(e3) transmitting the detected data as detection parameters

(e4) initiating an interval counter, and

(e5) transmitting an interval count as feedback data to step (e2), and

(f) formatting said detection parameters into a control packet.

2. The audio compression method, according to claim 1, further comprising the steps of:

(g) inserting the packet of detection parameters in steps (h) and (i),

(h) detecting an insert location,

(i) inserting message data of predetermined size, and

(j) outputting the compressed signals and message data to at least one client via a communication network.

3. The audio compression method, according to claim 2, further comprising the steps of:

(k) unformatting the audio data of the outputting step (j),

(l) detecting the unformatted audio data,

(m) generating a half wave fit for the detected audio data,

(n) generating jitter parameters,

(o) compensating said data of step (m) for jitter,

(p) storing said compensated audio data signals, and

(q) outputting the audio data signals via a speakerphone.

4. The audio compression method, according to claim 1, wherein said determining step (e1) further comprises the step of applying a spline fit to regenerate the data signals according to the equation:

INT((((WM_t+1+WM_t))−

((WM_t+1−

WM_t))*COS((180/(IC+1))*i*PI( )/180))/2)¦

where i=1 . . . interval count (IC).

5. The audio compression method, according to claim 1, wherein said sampling step (a):

include sampling at least one analog audio signal.

6. The audio compression method, according to claim 5, wherein said converting step (b):

includes converting at least one analog signal to a corresponding digital audio signal.

7. The audio compression method, according to claim 1, wherein said sampling step (a):

include sampling at least one digital audio signal.

8. The audio compression method, according to claim 7, wherein said converting step (b):

includes converting said at least one digital audio signal to a corresponding analog audio signal.

9. The audio compression method, according to claim 7, wherein said converting step (b):

includes converting said at least one digital audio signal to a corresponding analog audio signal.

10. An audio compression system for transmitting voice data over a communication network, comprising:

an audio microphone for detecting at least one analog voice signal in a computer;

said computer includes a first converter for converting analog signals to digital signals, and a compression controller for controlling and selectively packeting said at least one analog voice signal as digital output;

a decompressing controller for decompressing said digital output and storing said digital output; and

a second converter for converting said digital output to a corresponding analog out put signal.