A device comprising: a receiver configured to receive a bitstream from an encoder, the bitstream comprising at least a low-band mid channel bitstream, a high-band mid channel bandwidth extension, BWE, bitstream, and a stereo downmix/upmix parameter bitstream; a decoder configured to: decode the low-band mid channel bitstream to generate a low-band mid signal and a low-band mid excitation signal; generate a non-linear harmonic extension of the low-band mid excitation signal corresponding to a high-band BWE portion; decode the high-band mid channel BWE bitstream to generate a synthesized high-band mid signal based on the non-linear harmonic extension of the low-band mid excitation signal and based on high-band mid channel BWE parameters; determine an inter-channel bandwidth extension, ICBWE, gain mapping parameter corresponding to the synthesized high-band mid signal, the ICBWE gain mapping parameter based on a selected frequency-domain gain parameter that is extracted from the stereo downmix/upmix parameter bitstream, wherein the selected frequency-domain gain parameter is selected based on a spectral proximity of a frequency range of the selected frequency-domain gain parameter and a frequency range of the synthesized high-band mid signal; and perform a gain scaling operation on the synthesized high-band mid signal based on the ICBWE gain mapping parameter to generate a left high-band channel and a right high-band channel; and one or more speakers configured to output a first audio channel and a second audio channel, the first audio channel based on the left high-band channel, and the second audio channel based on the right high-band channel. a receiver configured to receive a bitstream from an encoder, the bitstream comprising at least a low-band mid channel bitstream, a high-band mid channel bandwidth extension, BWE, bitstream, and a stereo downmix/upmix parameter bitstream; a decoder configured to: decode the low-band mid channel bitstream to generate a low-band mid signal and a low-band mid excitation signal; generate a non-linear harmonic extension of the low-band mid excitation signal corresponding to a high-band BWE portion; decode the high-band mid channel BWE bitstream to generate a synthesized high-band mid signal based on the non-linear harmonic extension of the low-band mid excitation signal and based on high-band mid channel BWE parameters; determine an inter-channel bandwidth extension, ICBWE, gain mapping parameter corresponding to the synthesized high-band mid signal, the ICBWE gain mapping parameter based on a selected frequency-domain gain parameter that is extracted from the stereo downmix/upmix parameter bitstream, wherein the selected frequency-domain gain parameter is selected based on a spectral proximity of a frequency range of the selected frequency-domain gain parameter and a frequency range of the synthesized high-band mid signal; and perform a gain scaling operation on the synthesized high-band mid signal based on the ICBWE gain mapping parameter to generate a left high-band channel and a right high-band channel; and decode the low-band mid channel bitstream to generate a low-band mid signal and a low-band mid excitation signal; generate a non-linear harmonic extension of the low-band mid excitation signal corresponding to a high-band BWE portion; decode the high-band mid channel BWE bitstream to generate a synthesized high-band mid signal based on the non-linear harmonic extension of the low-band mid excitation signal and based on high-band mid channel BWE parameters; determine an inter-channel bandwidth extension, ICBWE, gain mapping parameter corresponding to the synthesized high-band mid signal, the ICBWE gain mapping parameter based on a selected frequency-domain gain parameter that is extracted from the stereo downmix/upmix parameter bitstream, wherein the selected frequency-domain gain parameter is selected based on a spectral proximity of a frequency range of the selected frequency-domain gain parameter and a frequency range of the synthesized high-band mid signal; and perform a gain scaling operation on the synthesized high-band mid signal based on the ICBWE gain mapping parameter to generate a left high-band channel and a right high-band channel; and one or more speakers configured to output a first audio channel and a second audio channel, the first audio channel based on the left high-band channel, and the second audio channel based on the right high-band channel.