Hierarchical encoding/decoding device

• US 8,374,853 B2
• Filed: 07/07/2006
• Issued: 02/12/2013
• Est. Priority Date: 07/13/2005
• Status: Expired due to Fees

• Current Assignee: Orange S.A.
• Original Assignee: Orange S.A.
• Inventors: Virette, David, Ragot, Stephane
• Primary Examiner(s): Guerra-Erazo, Edgar
• Application Number:
  US11/988,758
• Publication Number:
  US 20090326931A1
• Time in Patent Office: 2,412 Days
• Field of Search: 704/500, 704/502, 704/503, 704/504, 704/216, 704/219, 704/220, 704/223, 704/224, 704/225, 704/262, 704/222, 704/201, 704/205, 704/200.1, 704/501
• US Class Current: 704/220
• 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

A system for coding a hierarchical audio signal, comprising, at least, a core layer using parametric coding by analysis by synthesis in a first frequency band, a band extension layer for widening said first frequency band into a second frequency band, or wideband. The system also comprises a wideband audio coding quality enhancement layer based on transform coding using a spectral parameter obtained from said band extension layer. Application to transmitting speech and/or audio signals over packet networks.

Claims

1. A system for coding a hierarchical audio signal, comprising, at least, a core coding module using parametric coding by analysis by synthesis in a first frequency band, a band extension coding module for widening said first frequency band into a second frequency band, or wideband, wherein said system also comprises a wideband audio coding quality enhancement module based on transform coding using a spectral parameter obtained from said band extension coding module.

2. A coding system according to claim 1, wherein said system also comprises a first frequency band audio coding quality enhancement module.

3. The coding system according to claim 1, wherein said spectral parameter is a spectral envelope obtained from the band extension coding module.

4. The coding system according to claim 3, wherein said spectral envelope is specified by a wideband linear prediction filter.

5. The coding system according to claim 3, wherein said spectral envelope is given by the energy per sub-band of the signal.

6. The coding system according to claim 1, wherein said spectral parameter is at least a portion of a transform signal obtained from the signal synthesized by the band extension coding module.

7. The coding system according to claim 6, wherein said system comprises a module for progressive adjustment of the energy in sub-bands of the transform signal obtained from the signal synthesized by the band extension coding module.

8. A method for coding an audio signal, comprising the steps of:

coding an original signal in a first frequency band;

coding the original signal in an extension of the first frequency band;

calculating a residual signal from the original signal and the signals obtained from the preceding coding operations; and

producing an audio coding quality enhancement layer using transform coding, said transform coding of said residual signal using a spectral parameter obtained from the said extension of the first frequency band.

9. The method according to claim 8, wherein said spectral parameter is a spectral envelope obtained from the said extension of the first frequency band.

10. The method according to claim 8, wherein said spectral parameter is at least a portion of a transform signal obtained from the signal synthesized by the said extension of the first frequency band.

11. The method according to claim 8, wherein said method comprises a step of progressively adjusting the energy in sub-bands of the transform signal obtained from the signal synthesized by the said extension of the first frequency band.

12. A computer program stored on a non-transitory computer-readable medium and comprising program instructions for implementing the steps of the method according to claim 8, when said program is executed by a computer.

13. A hierarchical audio decoder, comprising:

a core decoder using parametric coding by analysis by synthesis, adapted to decode in a first frequency band a received signal coded by a coder comprising a core coding module using parametric coding by analysis by synthesis in the first frequency band, and a band extension coding module for widening said first frequency band into an extended frequency band;

a decoding module for decoding the extended frequency band of the first frequency band; and

a wideband audio decoding quality enhancement stage using transform decoding including an inverse transform using a spectral parameter obtained from the decoding of the extended frequency band of the first frequency band.

14. The decoder according to claim 13, wherein said spectral parameter is a spectral envelope obtained from the decoding of the extended frequency band of the first frequency band.

15. The decoder according to claim 13, wherein said spectral parameter is at least a portion of a transform signal obtained from the signal synthesized by the decoding of the extended frequency band of the first frequency band.

16. The decoder according to claim 13, wherein said decoder comprises a module for progressive adaptation of the energy in sub-bands of the spectrum generated by transform coding.

17. The decoder according to claim 13, wherein said core decoder includes a first frequency band audio decoding quality enhancement module.