Efficient and scalable parametric stereo coding for low bitrate audio coding applications

A method of decoding a bit stream comprising an encoded lowband signal and an encoded power spectral envelope of a stereo or multichannel signal having a first channel and a second channel, the method comprising:

• receiving the encoded lowband signal included in the bit stream;
• producing a lowband output signal, the lowband output signal having a lowband stereo signal;
• receiving the encoded power spectral envelope of the stereo signal or the multichannel signal having the first channel and the second channel, the first channel and the second channel having a set of frequency bands, the encoded power spectral envelope being represented by a balance parameter for each frequency band and a level parameter representing a total power of the first channel and the second channel for each frequency band;
• converting the balance parameters and the level parameters into power values of the first channel and the second channel;
• generating a synthetic highband signal using the lowband output signal;
• adjusting a spectral envelope of the synthetic highband signal using the power values of the first channel and the second channel to obtain an adjusted highband signal;
• and
• combining the adjusted highband signal and the lowband output signal to obtain a decoded stereo signal or a decoded multichannel signal.

A non-transitory storage medium having stored thereon a computer program for performing a method of decoding a bit stream comprising an encoded lowband signal and an encoded power spectral envelope of a stereo or multichannel signal having a first channel and a second channel, the method comprising:

• receiving the encoded lowband signal included in the bit stream;
• producing a lowband output signal, the lowband output signal having a lowband stereo signal, wherein the lowband core decoder is configured for receiving the encoded lowband signal included in the bit stream;
• receiving the encoded power spectral envelope of the stereo signal or the multichannel signal having the first channel and the second channel, the first channel and the second channel having a set of frequency bands, the encoded power spectral envelope being represented by a balance parameter for each frequency band and a level parameter representing a total power of the first channel and the second channel for each frequency band;
• converting the balance parameters and the level parameters into power values of the first channel and the second channel;
• generating a synthetic highband signal using the lowband output signal;
• adjusting a spectral envelope of the synthetic highband signal using the power values of the first channel and the second channel to obtain an adjusted highband signal;
• and
• combining the adjusted highband signal and the lowband output signal to obtain a decoded stereo signal or a decoded multichannel signal.