IL193786A

Apparatus and method for generating audio subband values and apparatus and method for generating time-domain samples

Abstract

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IL193786A, drawing sheet 1
Sheet 1 of 35

Term

No projected expiry on record.

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15 claims: 9 independent, 6 dependent

  1. 1
    Claims 1. Apparatus for generating audio subband values in audio subband channels, comprising :an analysis windower (110) for windowing a frame (120) of time-domain audio input samples being in a time sequence extending from an early sample to a later sample using an analysis window function (190) comprising a sequence of window coefficients to obtain windowed samples, the analysis window function comprising a first number of window coefficients derived from a larger window function comprising a sequence of a larger second number of window coefficients, wherein the window coefficients of the window function are derived by an interpolation of window coefficients of the larger window function;and wherein the second number is an even number;and a calculator (170) for calculating the audio subband values using the windowed samples.
  2. 3
    Apparatus (100) according to any of the preceding claims, wherein the apparatus (100) or the analysis windower (110) is adapted such that the window coefficients of the analysis window function are interpolated based on two consecutive window coefficients of the larger window function according to the sequence of the window coefficients of the larger window function to obtain one window coefficient of the window function.
  3. 4
    Apparatus (100) according to any of the preceding claims, wherein the apparatus (100) or the analysis windower (110) is adapted to obtain the window coefficients c (n) of the analysis window function based on the equation Φ) = f (c 2 (2n) + c 2 (2n + 1)) , wherein n is an integer indicating an index of the window coefficients c(n), and c 2 (n) is a window coefficient of the larger window function.
  4. 6
    Apparatus (100) according to any of the preceding claims, wherein the analysis windower (110) is adapted such that the larger window function is asymmetric with respect to the sequence of window coefficients .
  5. 7
    Apparatus (300) for generating time-domain audio samples, comprising:a calculator (310) for calculating a sequence (330) of intermediate time-domain samples from audio subband values in audio subband channels, the sequence comprising earlier intermediate time-domain samples and later time-domain samples;a synthesis windower (360) for windowing the sequence (330) of intermediate time-domain samples using a synthesis window function (370) comprising a sequence of window coefficients to obtain windowed intermediate time-domain samples, the synthesis window function comprising a first number of window coefficients derived from a larger window function comprising a sequence of a larger second number of window coefficients, wherein the window coefficients of the window function are derived by an interpolation of window coefficients of the larger window function;and wherein the second number is even;and an overlap-adder output stage (400) for processing the windowed intermediate time-domain samples to obtain the time-domain samples.
  6. 9
    Apparatus (300) according to any of the claims 7 or 8, wherein the apparatus (300) is adapted such that the window coefficients of the synthesis window function are interpolated based on two consecutive window coefficients of the larger window function according to the sequence of window coefficients of the larger window function to obtain one window coefficient of the window function.
  7. 10
    Apparatus (300) according to any of the claims 7 to 9, wherein the apparatus (300) is adapted to obtain the window coefficients c(n) of the synthesis window function based on equation c(n) = i ( c 2( 2n ) + c 2 (2n + 1)) , wherein c 2 (n) are window coefficients of a larger window function corresponding to the index n.
  8. 12
    Apparatus (300) according to any of the claims 7 to 11, wherein the synthesis windower (360) is adapted such that the larger window function is asymmetric with respect to a sequence window coefficients.
  9. 13
    Method for generating audio subband values in audio subband channels, comprising:windowing a frame of time-domain audio input samples being in a time sequence extending from an early sample to a later sample using an analysis window function to obtain windowed samples, the analysis window function comprising a first number of window coefficients derived from a larger window function comprising a sequence of a larger second number of window coefficients, wherein the window coefficients of the window function are derived by an interpolation by window coefficients of the larger window function;and wherein the second number is an even number;and calculating the audio subband values using the windowed samples.
  10. 14
    Method for generating time-domain audio samples, comprising :calculating a sequence of intermediate time-domain samples from audio subband values in audio subband channels, the sequence comprising earlier intermediate time-domain samples and later intermediate time-domain samples;windowing the sequence of intermediate time-domain samples using a synthesis window function to obtain windowed time-domain samples, the synthesis window function comprising a first number of window coefficients derived from a larger window function comprising a sequence of a larger second number of window coefficients, wherein the window coefficients of the window function are derived by an interpolation of window coefficients of the larger window function;and wherein the second number is even;and overlap-adding the windowed time-domain samples to obtain the time-domain samples.