Flexible and Scalable Combined Innovation Codebook for Use in CELP Coder and Decoder

• US 20120089389A1
• Filed: 04/11/2011
• Published: 04/12/2012
• Est. Priority Date: 04/14/2010
• Status: Active Grant

• Current Assignee: VoiceAge EVS LLC (FIG LLC (d/b/a Fortress Investment Group LLC))
• Original Assignee: VoiceAge Corporation
• Inventors: Bessette, Bruno
• Granted Patent: US 9,053,705 B2
• Time in Patent Office: Days
• US Class Current: 704/203
• CPC Class Codes: G10L 19/0212 using orthogonal transformation
• CPC Class Codes: G10L 19/09 Long term prediction, i.e. removing periodical redundancies, e.g. by using adaptive codebook or pitch predictor
• CPC Class Codes: G10L 19/12 the excitation function being a code excitation, e.g. in code excited linear prediction [CELP] vocoders
• CPC Class Codes: G10L 19/24 Variable rate codecs, e.g. for generating different qualities using a scalable representation such as hierarchical encoding or layered encoding

Abstract

In a CELP coder, a combined innovation codebook coding device comprises a pre-quantizer of a first, adaptive-codebook excitation residual, and a CELP innovation-codebook search module responsive to a second excitation residual produced from the first, adaptive-codebook excitation residual. In a CELP decoder, a combined innovation codebook comprises a de-quantizer of pre-quantized coding parameters into a first excitation contribution, and a CELP innovation-codebook structure responsive to CELP innovation-codebook parameters to produce a second excitation contribution.

Claims

1. A combined innovation codebook coding device, comprising:

a pre-quantizer of a first, adaptive-codebook excitation residual, the pre-quantizer operating in transform-domain; and

a CELP innovation-codebook module responsive to a second excitation residual produced from the first, adaptive-codebook excitation residual.

2. A combined innovation codebook coding device as defined in claim 1, wherein the first, adaptive-codebook excitation residual is obtained by subtracting an adaptive codebook contribution from an LP residual.

10. A combined innovation codebook coding device as defined in claim 1, wherein the CELP innovation-codebook module is an ACELP innovation-codebook search module.

11. A combined innovation codebook coding device as defined in claim 1, wherein the pre-quantizer quantizes only frequency-domain transform coefficients having an energy exceeding a specified threshold, so that spectral dynamics of the second excitation residual are reduced or maintained within a desired range.

3. A combined innovation codebook coding device, comprising:

a pre-quantizer of a first, adaptive-codebook excitation residual, the pre-quantizer operating in transform-domain; and

a CELP innovation-codebook module responsive to a second excitation residual produced from the first, adaptive-codebook excitation residual;

wherein the pre-quantizer comprises a calculator of a transform of the first, adaptive-codebook excitation residual to frequency-domain.

4. A combined innovation codebook coding device as defined in claim 3, wherein the transform is a DCT transform.

5. A combined innovation codebook coding device, comprising:

a pre-quantizer of a first, adaptive-codebook excitation residual, the pre-quantizer operating in transform-domain; and

a CELP innovation-codebook module responsive to a second excitation residual produced from the first, adaptive-codebook excitation residual;

wherein the pre-quantizer comprises a calculator of a transform of the first, adaptive-codebook excitation residual to frequency-domain, and a quantizer of the transformed, first adaptive-codebook excitation residual.

6. A combined innovation codebook coding device as defined in claim 5, wherein the quantizer of the transformed, first adaptive-codebook excitation residual is an algebraic vector quantizer.

9. A combined innovation codebook coding device as defined in claim 5, comprising a calculator of an inverse transform of the quantized and transformed, first adaptive-codebook excitation residual, a de-emphasis filter of the inverse-transformed adaptive-codebook excitation residual to produce a time-domain contribution, and a subtractor of the time-domain contribution from an adaptive-codebook contribution to produce the second excitation residual.

12. A combined innovation codebook coding device as defined in claim 5, wherein the quantizer encodes transform coefficients related to lower frequencies only, depending on an available bit-budget.

7. A combined innovation codebook coding device, comprising:

a pre-quantizer of a first, adaptive-codebook excitation residual, the pre-quantizer operating in transform-domain; and

a CELP innovation-codebook module responsive to a second excitation residual produced from the first, adaptive-codebook excitation residual;

wherein the pre-quantizer comprises a calculator of a transform of the first, adaptive-codebook excitation residual to frequency-domain, and a pre-emphasis filter of the first, adaptive-codebook excitation residual prior to calculating the transform of said first adaptive-codebook excitation residual.

8. A combined innovation codebook coding device as defined in claim 7, wherein the pre-emphasis filter emphasizes low frequencies of the first, adaptive-codebook excitation residual.

13. A CELP coder, comprising:

a combined innovation codebook coding device including (a) a pre-quantizer of a first, adaptive-codebook excitation residual, the pre-quantizer operating in transform-domain; and

(b) a CELP innovation-codebook module responsive to a second excitation residual produced from the first, adaptive-codebook excitation residual.

14. A combined innovation codebook comprising:

a de-quantizer of pre-quantized coding parameters into a first innovation excitation contribution, the de-quantizer comprising an inverse transform calculator responsive to the coding parameters; and

a CELP innovation-codebook structure responsive to CELP innovation-codebook parameters to produce a second innovation excitation contribution.

15. A combined innovation codebook as defined in claim 14, wherein the de-quantizer comprises a decoder for de-quantizing the pre-quantized coding parameters.

16. A combined innovation codebook as defined in claim 15, wherein the decoder comprises an AVQ decoder.

17. A combined innovation codebook comprising:

a de-quantizer of pre-quantized coding parameters into a first innovation excitation contribution, the de-quantizer comprising an inverse transform calculator responsive to the coding parameters; and

a CELP innovation-codebook structure responsive to CELP innovation-codebook parameters to produce a second innovation excitation contribution;

wherein the de-quantizer comprises a decoder for de-quantizing the pre-quantized coding parameters, and wherein the inverse transform calculator is responsive to the de-quantized coding parameters.

18. A combined innovation codebook as defined in claim 17, wherein the inverse transform is an inverse DCT transform.

19. A combined innovation codebook comprising:

a de-quantizer of pre-quantized coding parameters into a first innovation excitation contribution, the de-quantizer comprising an inverse transform calculator responsive to the coding parameters; and

a CELP innovation-codebook structure responsive to CELP innovation-codebook parameters to produce a second innovation excitation contribution;

wherein the de-quantizer comprises a decoder for de-quantizing the pre-quantized coding parameters, wherein the inverse transform calculator is responsive to the de-quantized coding parameters, and wherein the de-quantizer comprises a de-emphasis filter supplied with the inverse-transformed, de-quantized coding parameters to produce the first excitation contribution.

20. A CELP decoder, comprising:

a combined innovation codebook including (a) a de-quantizer of pre-quantized coding parameters into a first innovation excitation contribution, the de-quantizer comprising an inverse transform calculator responsive to the coding parameters; and

(b) a CELP innovation-codebook structure responsive to CELP innovation-codebook parameters to produce a second innovation excitation contribution.

21. A combined innovation codebook coding method, comprising:

pre-quantizing a first, adaptive-codebook excitation residual, the pre-quantizing being performed in transform-domain; and

searching a CELP innovation-codebook in response to a second excitation residual produced from the first, adaptive-codebook excitation residual.

22. A combined innovation codebook coding method as defined in claim 21, comprising obtaining the first, adaptive-codebook excitation residual by subtracting an adaptive codebook contribution from an LP residual.

30. A combined innovation codebook coding method as defined in claim 21, wherein the CELP innovation-codebook search is an ACELP innovation-codebook search.

31. A combined innovation codebook coding method as defined in claim 21, wherein pre-quantizing the first, adaptive-codebook excitation residual comprises pre-quantizing only frequency-domain transform coefficients having an energy exceeding a specified threshold, so that spectral dynamics of the second excitation residual are reduced or maintained within a desired range.

23. A combined innovation codebook coding method, comprising:

pre-quantizing a first, adaptive-codebook excitation residual, the pre-quantizing being performed in transform-domain; and

searching a CELP innovation-codebook in response to a second excitation residual produced from the first, adaptive-codebook excitation residual;

wherein pre-quantizing the first, adaptive-codebook excitation residual comprises calculating a transform of the first, adaptive-codebook excitation residual to frequency-domain.

24. A combined innovation codebook coding method as defined in claim 23, wherein the transform is a DCT transform.

25. A combined innovation codebook coding method, comprising:

pre-quantizing a first, adaptive-codebook excitation residual, the pre-quantizing being performed in transform-domain; and

searching a CELP innovation-codebook in response to a second excitation residual produced from the first, adaptive-codebook excitation residual;

wherein pre-quantizing the first, adaptive-codebook excitation residual comprises calculating a transform of the first, adaptive-codebook excitation residual to frequency-domain, and quantizing the transformed, first adaptive-codebook excitation residual.

26. A combined innovation codebook coding method as defined in claim 25, wherein quantizing the transformed, first adaptive-codebook excitation residual comprises algebraic vector quantizing said transformed, first adaptive-codebook excitation residual.

29. A combined innovation codebook coding method as defined in claim 25, comprising calculating an inverse transform of the quantized and transformed, first adaptive-codebook excitation residual, de-emphasis filtering the inverse-transformed adaptive-codebook excitation residual to produce a time-domain contribution, and subtracting the time-domain contribution from an adaptive-codebook contribution to produce the second excitation residual.

32. A combined innovation codebook coding method as defined in claim 25, wherein quantizing the transformed, first adaptive-codebook excitation residual comprises encoding transform coefficients related to lower frequencies only, depending on an available bit-budget.

27. A combined innovation codebook coding method, comprising:

pre-quantizing a first, adaptive-codebook excitation residual, the pre-quantizing being performed in transform-domain; and

searching a CELP innovation-codebook in response to a second excitation residual produced from the first, adaptive-codebook excitation residual;

wherein pre-quantizing the first, adaptive-codebook excitation residual comprises calculating a transform of the first, adaptive-codebook excitation residual to frequency-domain, and wherein said method comprises pre-emphasis filtering the first, adaptive-codebook excitation residual prior to calculating the transform of the first adaptive-codebook excitation residual.

28. A combined innovation codebook coding method as defined in claim 27, wherein pre-emphasis filtering comprises emphasizing low frequencies of the first, adaptive-codebook excitation residual.

33. A combined innovation codebook decoding method comprising:

de-quantizing pre-quantized coding parameters into a first innovation excitation contribution, wherein de-quantizing the pre-quantized coding parameters comprises calculating an inverse transform of the coding parameters; and

applying CELP innovation-codebook parameters to a CELP innovation-codebook structure to produce a second innovation excitation contribution.

34. A combined innovation codebook decoding method as defined in claim 33, wherein de-quantizing the pre-quantized coding parameters comprises decoding the pre-quantized coding parameters to produce de-quantized coding parameters.

35. A combined innovation codebook decoding method as defined in claim 34, wherein decoding the pre-quantized coding parameters comprises AVQ decoding said pre-quantized coding parameters.

36. A combined innovation codebook decoding method comprising:

de-quantizing pre-quantized coding parameters into a first innovation excitation contribution, wherein de-quantizing the pre-quantized coding parameters comprises calculating an inverse transform of the coding parameters; and

applying CELP innovation-codebook parameters to a CELP innovation-codebook structure to produce a second innovation excitation contribution;

wherein de-quantizing the pre-quantized coding parameters comprises decoding the pre-quantized coding parameters to produce de-quantized coding parameters, and wherein calculating an inverse transform of the coding parameters comprises calculating the inverse transform of the de-quantized coding parameters.

37. A combined innovation codebook decoding method as defined in claim 36, wherein the inverse transform is an inverse DCT transform.

38. A combined innovation codebook decoding method comprising:

de-quantizing pre-quantized coding parameters into a first innovation excitation contribution, wherein de-quantizing the pre-quantized coding parameters comprises calculating an inverse transform of the coding parameters; and

applying CELP innovation-codebook parameters to a CELP innovation-codebook structure to produce a second innovation excitation contribution;

wherein de-quantizing the pre-quantized coding parameters comprises decoding the pre-quantized coding parameters to produce de-quantized coding parameters, wherein calculating an inverse transform of the coding parameters comprises calculating the inverse transform of the de-quantized coding parameters, and wherein the combined innovation codebook decoding method comprises de-emphasis filtering the inverse-transformed, de-quantized coding parameters to produce the first innovation excitation contribution.