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Apparatus for encoding digital data with reduction of perceptible noise

  • US 5,502,789 A
  • Filed: 03/12/1993
  • Issued: 03/26/1996
  • Est. Priority Date: 03/07/1990
  • Status: Expired due to Term
First Claim
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1. Apparatus for encoding a digital signal comprised of a plurality of samples, said apparatus comprising:

  • frequency dividing means for dividing said digital signal comprised of said plurality of samples into a plurality of frequency divided signals within respective frequency bands;

    encoding means for encoding said frequency divided signals including block segmentation means for segmenting each of said frequency divided signals into respective size blocks each having a respective number of said samples, orthogonal transformation means for orthogonally transforming said blocks to form coefficient data, and quantization means for quantizing said coefficient data with a number of bits to form an encoded digital signal;

    transient detection means receiving at least the one of said plurality of frequency divided signals within the lowest of said frequency bands for detecting a transient in the received frequency divided signal within the lowest frequency band and for generating an output signal indicating that said transient has been detected; and

    control means responsive to said output signal from said transient detection means for controlling the encoding performed by said encoding means of at least said frequency divided signal within said lowest frequency band so as to reduce the perceptibility of noise in the encoded digital signal.

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