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Variable length coding using a plurality of region bit allocation patterns

  • US 5,924,064 A
  • Filed: 10/07/1996
  • Issued: 07/13/1999
  • Est. Priority Date: 10/07/1996
  • Status: Expired due to Term
First Claim
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1. A method for encoding an audio signal, comprising the steps of:

  • converting overlapping groups of digitized samples of the audio signal into frames of transform coefficients;

    grouping the transform coefficients in each frame into adjacent regions;

    determining power in each region from the transform coefficients in the region;

    deriving a plurality of categorizations to the transform coefficients, each categorization specifying, for each region, a predetermined rule for performing a scalar, non-uniform quantization with a predetermined step size;

    grouping a predetermined number of quantization scalars to form vectors; and

    performing statistically based variable-bit length encoding of the vectors;

    determining, for each one of the categorizations, the number of bits required to transmit the encoded transform coefficients to a decoder;

    quantizing and encoding the transform coefficients in accordance with one of the categorizations selected in accordance with a predetermined fidelity criteria and maximum bit rate;

    transmitting the quantized power, the quantized and encoded transform coefficients, and an identification of the selected one of the categorizations to a decoder.

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