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Method device and system for an efficient noise injection process for low bitrate audio compression

  • US 5,692,102 A
  • Filed: 10/26/1995
  • Issued: 11/25/1997
  • Est. Priority Date: 10/26/1995
  • Status: Expired due to Term
First Claim
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1. A system for efficient noise injection for low bitrate audio compression to maximize audio quality, wherein the system includes at least one of A-B;

  • A) the encoder including a noise substitution and normalization unit comprising;

    1) an encoder zero detection unit, coupled to receive a frequency domain quantized signal, for determining a control signal that indicates whether noise injection is implemented in accordance with a predetermined audio compression scheme;

    2) a normalization computation unit, coupled to receive at least unquantized subband values and the control signal from the encoder zero detection unit, for determining an energy normalization term based on the unquantized subband values when the control signal indicates all zero values for predefined regions;

    B) the decoder including a noise normalization and injection unit comprising;

    1) a decoder zero detection unit, coupled to receive a frequency domain quantized signal, for determining, a control signal that indicates implementation of noise injection is implemented in accordance with a predetermined audio compression scheme when values of the frequency domain quantized signal are zero; and

    2) a noise generation and normalization unit, coupled to receive the energy normalization term and the control signal from the decoder zero detection unit, for substituting a predetermined noise signal multiplied by the energy normalization term where indicated by the control signal,wherein the predetermined audio compression scheme comprises one of A-B;

    A) coding an individual quantizer step-size for each pre-defined frequency region; and

    B) coding a single global step-size for an entire frame of audio data.

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