Hybrid encoding of higher frequency and downmixed low frequency content of multichannel audio

A method for decoding an encoded audio signal indicative of waveform coded data and parametrically coded data, where the encoded audio signal has been generated by generating a downmix of low frequency components of at least some channels of a multichannel audio input signal, waveform coding each channel of the downmix, thereby generating the waveform coded data such that said waveform coded data are indicative of audio content of the downmix, performing parametric encoding on at least some higher frequency components of each channel of the input signal, thereby generating the parametrically coded data such that said parametrically coded data are indicative of said at least some higher frequency components of said each channel of the input signal, and generating the encoded audio signal in response to the waveform coded data and the parametrically coded data, said method including the steps of:

• (a) extracting the waveform encoded data and the parametrically encoded data from the encoded audio signal;
• (b) performing waveform decoding on the waveform encoded data extracted in step (a) to generate a first set of recovered frequency components indicative of low frequency audio content of each channel of the downmix;
• and
• (c) performing parametric decoding on the parametrically encoded data extracted in step (a) to generate a second set of recovered frequency components indicative of at least some higher frequency audio content of each channel of the multichannel audio input signal.

An audio decoder configured to decode an encoded audio signal indicative of waveform coded data and parametrically coded data, where the encoded audio signal has been generated by generating a downmix of low frequency components of at least some channels of a multichannel audio input signal having N channels, where N is an integer, waveform coding each channel of the downmix, thereby generating the waveform coded data such that said waveform coded data are indicative of audio content of the downmix, performing parametric encoding on at least some higher frequency components of each channel of the input signal, thereby generating the parametrically coded data such that said parametrically coded data are indicative of said at least some higher frequency components of said each channel of the input signal, and generating the encoded audio signal in response to the waveform coded data and the parametrically coded data, said decoder including:

• a first subsystem configured to extract the waveform encoded data and the parametrically encoded data from the encoded audio signal;
• and
• a second subsystem coupled and configured to perform waveform decoding on the waveform encoded data extracted by the first subsystem to generate a first set of recovered frequency components indicative of low frequency audio content of each channel of the downmix, and to perform parametric decoding on the parametrically encoded data extracted by the first subsystem to generate a second set of recovered frequency components indicative of at least some higher frequency audio content of each channel of the multichannel audio input signal.