Inter-channel bandwidth extension spectral mapping and adjustment

A method of encoding audio data, the method comprising:

• identifying a non-reference target channel based on temporal shift values in a current frame;
• generating a synthesized non-reference high-band channel based on a non-reference high-band excitation corresponding to the non-reference target channel;
• estimating one or more spectral mapping parameters based on a maximum-likelihood measure applied to the synthesized non-reference high-band channel and a high-band portion of the non-reference target channel;
• applying the one or more spectral mapping parameters to the synthesized non-reference high-band channel to generate a spectrally shaped synthesized non-reference high-band channel;
• generating an encoded bitstream based on the one or more spectral mapping parameters and the spectrally shaped synthesized non-reference high-band channel;
• and
• transmitting the encoded bitstream to a second device.

A device comprising:

• means for identifying a non-reference target channel based on temporal shift values in a current frame;
• means for generating a high-band portion of the non-reference target channel;
• means for generating a synthesized non-reference high-band channel based on a non-reference high-band excitation corresponding to the non-reference target channel;
• means for estimating one or more spectral mapping parameters based on a maximum-likelihood measure applied to the synthesized non-reference high-band channel and the high-band portion of the non-reference target channel;
• means for applying the one or more spectral mapping parameters to the synthesized non-reference high-band channel to generate a spectrally shaped synthesized non-reference high-band channel;
• means for generating an encoded bitstream based on the one or more spectral mapping parameters and the spectrally shaped synthesized non-reference high-band channel;
• and
• means for transmitting the encoded bitstream to a second device.

A device comprising:

• a decoder configured to:
• generate a reference channel and a non-reference target channel from a received low-band bitstream, the low-band bitstream received from an encoder of a second device;
• identify a non-reference target channel based on temporal shift values in a current frame;
• generate a synthesized non-reference high-band channel based on a maximum-likelihood measure applied to the non-reference high-band excitation corresponding to the non-reference target channel;
• extract one or more spectral mapping parameters from a received spectral mapping bitstream, the spectral mapping bitstream received from the encoder of the second device;
• generate a spectrally shaped synthesized non-reference high-band channel by applying the one or more spectral mapping parameters to the synthesized non-reference high-band channel;
• and
• generate an output signal based at least on the spectrally shaped synthesized non-reference high-band channel, the reference channel, and the non-reference target channel.