Method and apparatus for compressing audio signals

• US 6,029,127 A
• Filed: 03/28/1997
• Issued: 02/22/2000
• Est. Priority Date: 03/28/1997
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Delargy, Jeffrey T., Kressin, Mark S.
• Primary Examiner(s): Dorvil, Richemond
• Application Number:
  US08/827,550
• Time in Patent Office: 1,061 Days
• Field of Search: 704/500, 704/501, 704/502, 704/503, 704/200, 704/215, 704/210, 704/233, 704/201, 704/226
• US Class Current: 704/215
• CPC Class Codes: G10L 19/012 Comfort noise or silence coding

Abstract

An audio data compression method improves over existing standards because of its encoding strategy for silence. The method analyzes the audio input to an encoder. If the audio is for an analyzed time frame is silence, a single byte output is generated by the encoder. If the next frame is silence, no output is generated. When a receiver receives the compressed data, and detects a one-byte silence signal, it can capture that signal and repeat it to a decoder. When the compressed signal reaches the decoder, it is decompressed into an analog signal.

Claims

1. A method of audio compression comprising the steps of:

(a) monitoring an audio input;

(b) characterizing said audio input as silence and non-silence; and

(c) outputting a single representative frame for said silence until non-silence is detected.

2. The method of claim 1 wherein the representative frame is a single byte.

3. The method of claim 1 further comprising:

(d) outputting no data between output of the representative frame and detection of non-silence.

4. The method of claim 1 wherein step (a) comprises:

(i) receiving an audio input at an encoder;

(ii) analyzing said input in a plurality of sequential time frames.

5. The method of claim 4 wherein the step of analyzing comprises analyzing 30 msec time frames of the audio input for the silence.

6. The method of claim 1 wherein step (b) comprises comparing the spectral characteristic of the analyzed audio input to a predetermined spectral characteristic.

7. The method of claim 1 further comprising:

(d) receiving the single representative frame;

(e) repeating the single representative frame to a decoder.

8. The method of claim 7 further comprising:

(f) decoding the single representative frame.

9. The method of claim 8 further comprises:

(g) outputting the decoded output to a speaker.

10. The method of claim 8 further comprises:

(g) outputting the decoded output to a speaker.

12. The method of claim 10 wherein step (d) comprises:

(i) encoding a first time frame of silence with a four byte output;

(ii) encoding a second time frame of silence with a one byte output; and

(iii) encoding a third time frame of silence with no data output.

13. The method of claim 10 further comprises:

(e) receiving the one byte output;

(f) repeating the one byte output to a decoder.

14. The method of claim 12 further comprises:

(g) decoding the received output.

11. A method of encoding a silence in an audio compression scheme comprising:

(a) analyzing a time frame of audio input;

(b) comparing the spectral characteristics of the analyzed input to a predetermined spectral characteristic;

(c) classifying said time frame as silence and non-silence; and

(d) encoding said silence with a single byte output until non-silence is detected.

15. An encoder for audio compression comprising:

(a) a detector for an audio input;

(b) means for characterizing said audio input as silence and non-silence; and

(c) means for outputting a single representative frame for said silence.

16. The encoder of claim 15 wherein the representative frame is one byte.

17. the encoder of claim 15 further comprises:

(d) means for outputting no data between output of the representative frame and detection of non-silence.