Audio encoder and decoder for interleaved waveform coding

An audio decoder for decoding an encoded audio signal, the audio decoder comprising:

• an input interface configured to receive a first waveform-coded signal having a spectral content up to a first cross-over frequency, a second waveform-coded signal having a spectral content corresponding to a subset of the frequency range above the first cross-over frequency, a control signal comprising data relating to one or more time ranges and one or more frequency ranges above the first cross-over frequency for which the second waveform-coded signal is available, and high frequency reconstruction parameters;
• a high frequency reconstructor configured to receive the first waveform-decoded signal and the high frequency reconstruction parameters from the receiving stage and to perform high frequency reconstruction using the first waveform-coded signal and the high frequency reconstruction parameters so as to generate a frequency extended signal having a spectral content above the first cross-over frequency;
• and an interleaver configured to receive the frequency extended signal from the high frequency reconstruction stage and the second waveform-coded signal from the receiving stage, and to interleave the frequency extended signal with the second waveform-coded signal based on the control signal,
• wherein the control signal comprises a vector indicating the one or more frequency ranges above the first cross-over frequency for which the second waveform-coded signal is available for interleaving with the frequency extended signal and indicating the one or more time ranges for which the second waveform-coded signal is available for interleaving with the frequency extended signal,
• wherein the audio decoder is implemented at least in part with hardware.

An encoding method in an audio processing system, comprising the steps of:

• receiving an audio signal to be encoded;
• calculating, based on the received audio signal, high frequency reconstruction parameters enabling high frequency reconstruction of the received audio signal above a first cross-over frequency;
• identifying, based on the received audio signal, a subset of the frequency range above the first cross-over frequency for which the spectral content of the received audio signal is to be waveform-coded and subsequently, in a decoder, be interleaved with a high frequency reconstruction of the audio signal;
• generating a first waveform-coded signal by waveform-coding the received audio signal for spectral bands up to the first cross-over frequency;
• a second waveform-coded signal by waveform-coding the received audio signal for spectral bands corresponding to the identified subset of the frequency range above the first cross-over frequency, and a control signal comprising data relating to one or more time ranges and one or more frequency ranges above the first cross-over frequency for which the second waveform-coded signal is available,
• wherein the control signal comprises vector indicating the one or more frequency ranges above the first cross-over frequency for which the second waveform-coded signal is available for interleaving with the high frequency reconstruction of the audio signal and indicating the one or more time ranges for which the second waveform-coded signal is available for interleaving with the high frequency reconstruction of the audio signal,
• wherein the audio processing system is implemented at least in part with hardware.