High-band signal coding using multiple sub-bands

An apparatus comprising:

• a low-band encoder of a vocoder configured to:
• receive an audio signal sampled at a first sample rate;
• and
• generate a low-band excitation signal based on a low-band portion of the audio signal;
• a high-band encoder of the vocoder configured to:
• generate a first baseband signal, wherein generating the first baseband signal includes performing a spectral flip operation on a nonlinearly transformed version of the low-band excitation signal, the first baseband signal corresponding to a first sub-band of a high-band portion of the audio signal;
• generate a second baseband signal corresponding to a second sub-band of the high-band portion of the audio signal, wherein the first sub-band is distinct from the second sub-band;
• output high-band side information to a decoder, the high-band side information based at least in part on the first baseband signal and the second baseband signal.

A non-transitory computer-readable medium comprising instructions that, when executed by a processor within a vocoder, cause the processor to perform operations comprising:

• receiving an audio signal sampled at a first sample rate;
• generating, at a low-band encoder of the vocoder, a low-band excitation signal based on a low-band portion of the audio signal;
• generating a first baseband signal at a high-band encoder of the vocoder, wherein generating the first baseband signal includes performing a spectral flip operation on a nonlinearly transformed version of the low-band excitation signal, the first baseband signal corresponding to a first sub-band of a high-band portion of the audio signal;
• generating a second baseband signal corresponding to a second sub-band of the high-band portion of the audio signal, wherein the first sub-band is distinct from the second sub-band;
• and
• outputting high-band side information to a decoder, the high-band side information based at least in part on the first baseband signal and the second baseband signal.

An apparatus comprising:

• means for receiving an audio signal sampled at a first sample rate;
• and
• means for generating a low-band excitation signal based on a low-band portion of the audio signal;
• means for generating a first baseband signal, wherein generating the first baseband signal includes performing a spectral flip operation on a nonlinearly transformed version of the low-band excitation signal, the first baseband signal corresponding to a first sub-band of a high-band portion of the audio signal;
• means for generating a second baseband signal corresponding to a second sub-band of the high-band portion of the audio signal, wherein the first sub-band is distinct from the second sub-band;
• and
• means for outputting high-band side information to a decoder, the high-band side information based at least in part on the first baseband signal and the second baseband signal.