SIGNAL PROCESSING APPARATUS AND METHOD, AND PROGRAM

• US 20190164558A1
• Filed: 01/31/2019
• Published: 05/30/2019
• Est. Priority Date: 08/03/2010
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Yamamoto, Yuki, Chinen, Toru, Hatanaka, Mitsuyuki
• Granted Patent: US 11,011,179 B2
• Time in Patent Office: Days
• CPC Class Codes: G10L 19/02 using spectral analysis, e.g. transform vocoders or subband vocoders
• CPC Class Codes: G10L 19/26 Pre-filtering or post-filtering
• CPC Class Codes: G10L 21/038 using band spreading techniques

Abstract

A method, system, and computer program product for processing an encoded audio signal is described. In one exemplary embodiment, the system receives an encoded low-frequency range signal and encoded energy information used to frequency shift the encoded low-frequency range signal. The low-frequency range signal is decoded and an energy depression of the decoded signal is smoothed. The smoothed low-frequency range signal is frequency shifted to generate a high-frequency range signal. The low-frequency range signal and high-frequency range signal are then combined and outputted.

Claims

1. A computer-implemented method for processing an audio signal, the method comprising:

decoding an encoded signal corresponding to the audio signal to produce a decoded signal having an energy spectrum of a shape including an energy depression;

performing filter processing on the decoded signal, the filter processing separating the decoded signal into low-frequency range band signals by using a QMF analysis filter;

computing an average energy of a plurality of the low-frequency range band signals;

computing a ratio for a selected one of the low-frequency range band signals by computing a ratio of the average energy of the plurality of the low-frequency range band signals to an energy for the selected low-frequency range band signal;

multiplying the selected low-frequency range band signal by the computed ratio for smoothing the energy depression of the low-frequency range band signals;

performing a frequency shift on the smoothed low-frequency range band signals, the frequency shift generating high-frequency range band signals from the low-frequency range band signals;

combining the low-frequency range band signals and the high-frequency range band signals to generate an output signal by using a QMF synthesis filter; and

outputting the output signal.

2. A device for processing an audio signal, the device comprising:

a low-frequency range decoding circuit configured to decode an encoded signal corresponding to the audio signal to produce a decoded signal having an energy spectrum of a shape including an energy depression;

a filter processor configured to perform filter processing on the decoded signal, the filter processing separating the decoded signal into low-frequency range band signals by using a QMF analysis filter;

a high-frequency range generating circuit configured to;

compute an average energy of a plurality of the low-frequency range band signals;

compute a ratio for a selected one of the low-frequency range band signals by computing a ratio of the average energy of the plurality of the low-frequency range band signals to an energy for the selected low-frequency range band signal;

multiply the selected low-frequency range band signal by the computed ratio for smoothing the energy depression of the low-frequency range band signals; and

perform a frequency shift on the smoothed low-frequency range band signals, the frequency shift generating high-frequency range band signals from the low-frequency range band signals; and

a combinatorial circuit configured to combine the low-frequency range band signals and the high-frequency range band signals to generate an output signal by using a QMF synthesis filter, and to output the output signal.

3. A non-transitory computer-readable storage medium including instructions that, when executed by a processor, perform a method for processing an audio signal, the method comprising:

decoding an encoded signal corresponding to the audio signal to produce a decoded signal having an energy spectrum of a shape including an energy depression;

performing filter processing on the decoded signal, the filter processing separating the decoded signal into low-frequency range band signals by using a QMF analysis filter;

computing an average energy of a plurality of the low-frequency range band signals;

computing a ratio for a selected one of the low-frequency range band signals by computing a ratio of the average energy of the plurality of the low-frequency range band signals to an energy for the selected low-frequency range band signal;

multiplying the selected low-frequency range band signal by the computed ratio for smoothing the energy depression of the low-frequency range band signals;

performing a frequency shift on the smoothed low-frequency range band signals, the frequency shift generating high-frequency range band signals from the low-frequency range band signals;

combining the low-frequency range band signals and the high-frequency range band signals to generate an output signal by using a QMF synthesis filter; and

outputting the output signal.