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Switching between coding schemes

  • US 20060173675A1
  • Filed: 03/11/2003
  • Published: 08/03/2006
  • Est. Priority Date: 03/11/2003
  • Status: Active Grant
First Claim
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1. Method for supporting a switching from a first coding scheme to a second coding scheme at an encoding end of a hybrid coding system, both coding schemes coding signals on a frame-by-frame basis, which second coding scheme is a Modified Discrete Cosine Transform based coding scheme calculating at the encoding end a Modified Discrete Cosine Transform with a window (h(n)) of a first type for a respective coding frame, a window (h(n)) of said first type satisfying constraints of perfect reconstruction, said method comprising:

  • providing for each first coding frame, which is to be encoded based on said second coding scheme after a preceding coding frame has been encoded based on said first coding scheme, a sequence of windows (h0(n),h1(n),h2(n)), wherein said window sequence splits the spectrum of a respective first coding frame into nearly uncorrelated spectral components when used as basis for forward Modified Discrete Cosine Transforms, and wherein the second half of the last window (h2(n)) of said sequence of windows is identical to the second half of a window (h(n)) of said first type; and

    calculating for a respective first coding frame a forward Modified Discrete Cosine Transform with each window (h0(n),h1(n),h2(n)) of said window sequence and providing the resulting samples as encoded samples of said respective first coding frame.

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