Audio encoder and decoder for interleaved waveform coding
AssigneeDolby International AB
InventorsKristofer KJOERLING, Robin THESING, Harald MUNDT, Heiko PURNHAGEN, Karl Jonas ROEDEN
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Abstract
There is provided methods and apparatuses for decoding and encoding of audio signals. In particular, a method for decoding includes receiving a waveform-coded signal having a spectral content corresponding to a subset of the frequency range above a cross-over frequency. The waveform-coded signal is interleaved with a parametric high frequency reconstruction of the audio signal above the cross-over frequency. In this way an improved reconstruction of the high frequency bands of the audio signal is achieved.
Claims25
1-20. (canceled)
A method for decoding an audio signal in an audio processing system, the method comprising:
- receiving a first waveform-coded signal having a spectral content up to a first cross-over frequency;
- receiving a second waveform-coded signal having spectral content corresponding to a subset of a frequency range above the first cross-over frequency;
- receiving high frequency reconstruction parameters;
- performing high frequency reconstruction using at least a portion of the first waveform-coded signal and the high frequency reconstruction parameters so as to generate a frequency extended signal having spectral content above the first cross-over frequency;
- adjusting energy levels of subbands of the frequency extended signal based on a target energy levels for the subbands;
- and
- interleaving the frequency extended signal with the second waveform-coded signal to generate an interleaved signal, such that spectral envelope energy levels for subbands of the interleaved signal corresponding to the target energy levels for the subbands.
An apparatus for decoding an encoded audio signal, the apparatus 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 spectral content corresponding to a subset of a frequency range above the first cross-over frequency, and high frequency reconstruction parameters;
- high frequency reconstructor configured to receive the first waveform-coded signal and the high frequency reconstruction parameters from the input interface 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 spectral content above the first cross-over frequency, adjust energy levels of subbands of the frequency extended signal based on target energy levels for the subbands;
- and
- an interleaver configured to receive the frequency extended signal from the high frequency reconstructor and the second waveform-coded signal from the input interface, and to interleave the frequency extended signal with the second waveform-coded signal to generate an interleaved signal, such that spectral envelope energy levels for subbands of the interleaved signal corresponding to the target energy levels.
An encoding method in an audio processing system, comprising:
- receiving an audio signal to be encoded;
- identifying, based on the received audio signal, a subset of a frequency range above a first cross-over frequency for which spectral content of the received audio signal is to be waveform-coded resulting in an waveform signal;
- determining a second waveform-coded signal based on at least one tonal component of the waveform signal;
- generating a first waveform-coded signal by waveform-coding the received audio signal for spectral bands up to the first cross-over frequency and the 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
- calculating, based on the received audio signal, high frequency reconstruction parameters enabling high frequency reconstruction, in a decoder, of the received audio signal above the first cross-over frequency, wherein said high frequency reconstruction uses the first waveform-coded signal and the high frequency reconstruction parameters so as to generate a frequency extended signal having spectral content above the first cross-over frequency and the frequency extended signal is to be interleaved with the second waveform-coded signal.
Dependencies are inferred from the claim text.