Audio Coding System Using Temporal Shape of a Decoded Signal to Adapt Synthesized Spectral Components

• US 20090144055A1
• Filed: 02/04/2009
• Published: 06/04/2009
• Est. Priority Date: 06/17/2002
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Davidson, Grant Allen, Truman, Michael Mead, Vinton, Mark Stuart, Fellers, Matthew Conrad
• Granted Patent: US 8,050,933 B2
• Time in Patent Office: Days
• US Class Current: 704/226
• CPC Class Codes: G10L 19/035 Scalar quantisation
• CPC Class Codes: G10L 21/038 using band spreading techniques

Abstract

A receiver in an audio coding system receives a signal conveying frequency subband signals representing an audio signal. The subband signals are examined to assess one or more characteristics of the audio signal including temporal shape. Spectral components are synthesized having the one or more assessed characteristics, integrated with the subband signals and passed through a synthesis filterbank to generate an output signal.

Claims

1. A method for processing encoded audio information, wherein the method comprises:

receiving the encoded audio information and obtaining therefrom subband signals representing spectral components of an audio signal;

examining some but not all of the subband signals to obtain an indication of temporal shape of the audio signal;

generating synthesized signal components and modifying the synthesized signal components in response to the indication of temporal shape to obtain modified synthesized signal components;

integrating the modified synthesized signal components with the subband signals to obtain a set of modified subband signals; and

generating the audio information by applying a synthesis filterbank to the set of modified subband signals.

2. The method of claim 1, wherein the method modifies the synthesized signal components in response to the indication of temporal shape by applying a filter to at least some of the generated synthesized signal components.

3. The method of claim 2 that obtains control information from the encoded information and adapts the filter in response to the control information.

4. The method of claim 1 that obtains the set of modified subband signals by combining the modified synthesized signal components with respective components of the subband signals.

5. The method of claim 1 that

obtains the indication of temporal shape of the audio signal by examining components of one or more subband signals in a first portion of spectrum;

and

generates the synthesized signal components by copying one or more components of the subband signals in the first portion of spectrum to a second portion of spectrum to form synthesized subband signals and modifying the copied components in response to the indication of temporal shape.

6. An apparatus for processing encoded audio information, wherein the apparatus comprises:

an input terminal that receives the encoded audio information;

memory; and

processing circuitry coupled to the input terminal and the memory;

wherein the processing circuitry is adapted to;

receive the encoded audio information and obtain therefrom subband signals representing spectral components of an audio signal;

examine some but not all of the subband signals to obtain an indication of temporal shape of the audio signal;

generate synthesized signal components and modify the synthesized signal components in response to the indication of temporal shape to obtain modified synthesized signal components;

integrate the modified synthesized signal components with the subband signals to obtain a set of modified subband signals; and

generate the audio information by applying a synthesis filterbank to the set of modified subband signals.

7. The apparatus of claim 6, wherein the processing circuitry is adapted to modify the synthesized signal components in response to the indication of temporal shape by applying a filter to at least some of the generated synthesized signal components.

8. The apparatus of claim 7, wherein the processing circuitry is adapted to obtain control information from the encoded information and adapt the filter in response to the control information.

9. The apparatus of claim 6, wherein the processing circuitry is adapted to obtain the set of modified subband signals by combining the modified synthesized signal components with respective components of the subband signals.

10. The apparatus of claim 6, wherein the processing circuitry is adapted to:

obtain the indication of temporal shape of the audio signal by examining components of one or more subband signals in a first portion of spectrum; and

generate the synthesized signal components by copying one or more components of the subband signals in the first portion of spectrum to a second portion of spectrum to form synthesized subband signals and modifying the copied components in response to the indication of temporal shape.

11. A storage medium that is readable by a device and that records a program of instructions executable by the device to perform a method for processing encoded audio information, wherein the method comprises:

receiving the encoded audio information and obtaining therefrom subband signals representing spectral components of an audio signal;

examining some but not all of the subband signals to obtain an indication of temporal shape of the audio signal;

generating synthesized signal components and modifying the synthesized signal components in response to the indication of temporal shape to obtain modified synthesized signal components;

integrating the modified synthesized signal components with the subband signals to obtain a set of modified subband signals; and

generating the audio information by applying a synthesis filterbank to the set of modified subband signals.

12. The of claim 11, wherein the method modifies the synthesized signal components in response to the indication of temporal shape by applying a filter to at least some of the generated synthesized signal components.

13. The storage medium of claim 12, wherein the method obtains control information from the encoded information and adapts the filter in response to the control information.

14. The storage medium of claim 11, wherein the method obtains the set of modified subband signals by combining the modified synthesized signal components with respective components of the subband signals.

15. The storage medium of claim 11, wherein the method:

obtains the indication of temporal shape of the audio signal by examining components of one or more subband signals in a first portion of spectrum; and

generates the synthesized signal components by copying one or more components of the subband signals in the first portion of spectrum to a second portion of spectrum to form synthesized subband signals and modifying the copied components in response to the indication of temporal shape.