Audio encoder

• US 20040267532A1
• Filed: 06/29/2004
• Published: 12/30/2004
• Est. Priority Date: 06/30/2003
• Status: Abandoned Application

• Current Assignee: Nokia Solutions and Networks US LLC (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Black, Alastair
• Application Number:
  US10/880,292
• Publication Number:
  US 20040267532A1
• Time in Patent Office: Days
• US Class Current: 704/268
• CPC Class Codes: G10L 19/20 using sound class specific coding, hybrid encoders or object based coding

Abstract

An audio encoder, for encoding an input signal, comprising:

a speech encoder for encoding the input signal to produce a synthetic signal;

a delay compensator for delaying the input signal;

combination means for combining the delayed input signal and synthetic signal into a combined signal; and

means for audio encoding the combined signal.

Claims

1. An audio encoder, for encoding an input signal, comprising:

a speech encoder for encoding the input signal to produce a synthetic signal;

a non-linear delay compensator for delaying the input signal;

combination means for combining the delayed input signal and synthetic signal into a combined signal; and

means for audio encoding the combined signal.

2. An audio encoder as claimed in claim 1, wherein the combination means includes means for transforming the delayed input signal from the time domain to the frequency domain;

means for transforming the synthetic signal from the time domain to the frequency domain; and

means for obtaining the difference between the transformed delayed input signal and the transformed synthetic signal.

3. An audio encoder as claimed in claim 1, further comprising:

first conversion means for converting the input signal from a first bit rate to a second bit rate before speech encoding and second conversion means for converting the synthetic signal from the second bit rate to the first bit rate.

4. An audio encoder as claimed in claim 1 wherein the speech encoder includes a non-linear filter.

5. An audio encoder as claimed in claim 1, wherein the speech encoder includes an infinite impulse response filter.

6. An audio encoder as claimed in claim 1, wherein the speech encoder complies with a cellular telecommunications standard.

7. An audio encoder as claimed in claim 1, wherein the speech encoder operates at a second sampling rate, less that the sampling rate of operation of the audio codec.

8. An audio encoder as claimed in claim 1, wherein the delay compensator compensates for a delay introduced by the speech encoder.

9. An audio encoder as claimed in claim 1, wherein the delay compensator includes a first time shift component compensating for a predictive nature of the speech encoder.

10. An audio encoder as claimed in claim 1, wherein the delay compensator includes a second time shift component compensating for bit rate conversion.

11. An audio encoder as claimed in claim 9, wherein the delay compensator includes a non-linear component.

12. An audio encoder for encoding an input signal comprising

a speech encoder for encoding the input signal;

a non-linear delay compensator for delaying the input signal; and

an audio encoder in series with the delay compensator, wherein the series combination of the delay compensator and audio encoder is in cascade with the speech encoder.

13. A method of using an extant speech encoder in an audio encoder comprising the steps of:

encoding an input signal using the speech encoder including a non-linear filter to produce a synthetic signal;

delaying the input signal to compensate for a delay introduced by the speech encoder;

combining the delayed input signal and the synthetic signal into a combined signal; and

audio encoding the combined signal.

14. A method as claimed in claim 13, wherein the step of combining includes transforming the delayed input signal from the time domain to the frequency domain;

transforming the synthetic signal from the time domain to the frequency domain; and

obtaining the difference between the transformed delayed input signal and the transformed synthetic signal.

15. A method as claimed in claim 13, further comprising the steps of converting the input signal from a first bit rate to a second bit rate before the encoding step and converting the synthetic signal from the second bit rate to the first bit rate before the combining step.

16. A method as claimed in claim 13, wherein the step of encoding using the speech encoder is performed at a second bit rate, less that the bit rate of audio encoding.

17. A method as claimed in claim 13, wherein the step of delaying compensates for a predictive nature of the speech encoder.

18. A method as claimed in claim 13, wherein the step of delaying compensates for bit rate conversion of the synthetic signal.

19. A method as claimed in claim 13, wherein the step of delaying compensates for a non-linear delay introduced by the speech encoder.