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Audio encoder and decoder using a frequency domain processor with full-band gap filling and a time domain processor

  • US 10,332,535 B2
  • Filed: 01/24/2017
  • Issued: 06/25/2019
  • Est. Priority Date: 07/28/2014
  • Status: Active Grant
First Claim
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1. An audio encoder for encoding an audio signal to generate an encoded audio signal, comprising:

  • a first encoding processor for encoding a first audio signal portion in a frequency domain, wherein the first encoding processor comprises;

    a time frequency converter for converting the first audio signal portion into a frequency domain representation comprising spectral lines up to a maximum frequency of the first audio signal portion;

    an analyzer for analyzing the frequency domain representation up to the maximum frequency to determine first spectral portions to be encoded with a first spectral resolution and second spectral portions to be encoded with a second spectral resolution, the second spectral resolution being lower than the first spectral resolution, wherein the analyzer is configured to determine a first spectral portion from the first spectral portions, the first spectral portion being placed, with respect to frequency, between two second spectral portions from the second spectral portions;

    a spectral encoder for encoding the first spectral portions with the first spectral resolution and for encoding the second spectral portions with the second spectral resolution, wherein the spectral encoder comprises a parametric coder for calculating spectral envelope information comprising the second spectral resolution from the second spectral portions;

    a second encoding processor for encoding a second different audio signal portion in the time domain, wherein the second encoding processor comprises;

    a sampling rate converter for converting the second audio signal portion to a lower sampling rate representation, the lower sampling rate being lower than a sampling rate of the audio signal, wherein the lower sampling rate representation does not comprise a high band of the audio signal;

    a time domain low band encoder for time domain encoding the lower sampling rate representation; and

    a time domain bandwidth extension encoder for parametrically encoding the high band of the audio signal;

    a controller configured for analyzing the audio signal and for determining, which portion of the audio signal is the first audio signal portion encoded in the frequency domain and which portion of the audio signal is the second audio signal portion encoded in the time domain; and

    an encoded signal former for forming the encoded audio signal comprising a first encoded signal portion for the first audio signal portion and a second encoded signal portion for the second audio signal portion,wherein the analyzer is configured to perform a temporal tile shaping or temporal noise shaping analysis or an operation of setting to zero spectral values in the second spectral portions, wherein the first encoding processor is configured to perform a shaping of spectral values of the first spectral portions using prediction coefficients derived from the first audio signal portion, and wherein the first encoding processor is furthermore configured to perform a quantization and entropy coding operation of shaped spectral values of the first spectral portions, and wherein spectral values of the second spectral portions are set to zero,the audio encoder further comprising a cross-processor, wherein the cross-processor comprises;

    a noise shaper for shaping quantized spectral values of the first spectral portions using LPC coefficients derived from the first audio signal portion;

    a spectral decoder for decoding the spectrally shaped spectral portions of the first spectral portion with a high spectral resolution and for synthesizing second spectral portions using a parametric representation of the second spectral portions and at least a decoded first spectral portion to acquire a decoded spectral representation;

    a frequency-time converter for converting the decoded spectral representation into the time domain to acquire a decoded first audio signal portion, wherein a sampling rate associated with the decoded first audio signal portion is different than a sampling rate of the audio signal, and a sampling rate associated with an output signal of the frequency-time converter is different from a sampling rate of an audio signal input into the time-frequency-converter,wherein at least one of the first encoding processor, the time frequency converter, the analyzer, the spectral encoder, the second encoding processor, the sampling rate converter, the time domain low band encoder, the time domain bandwidth extension encoder, the controller, the encoded signal former, the cross-processor, the noise shaper, the spectral decoder and the frequency-time converter is implemented, at least in part, by a hardware element of the audio encoder.

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