Methods, encoder and decoder for linear predictive encoding and decoding of sound signals upon transition between frames having different sampling rates

  • US 9,852,741 B2
  • Filed: 04/02/2015
  • Issued: 12/26/2017
  • Est. Priority Date: 04/17/2014
  • Status: Active Grant
First Claim
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1. A method for encoding a sound signal, comprising:

  • producing, in response to the sound signal, parameters for encoding the sound signal during successive sound signal processing frames, wherein the sound signal encoding parameters include linear predictive (LP) filter parameters, wherein producing the LP filter parameters comprises, when switching from a first one of the frames using an internal sampling rate S1 to a second one of the frames using an internal sampling rate S2, converting the LP filter parameters from the first frame from the internal sampling rate S1 to a the internal sampling rate S2, the and wherein converting the LP filter parameters from the first frame comprises;

    computing, at the internal sampling rate SI, a power spectrum of a LP synthesis filter using the LP filter parameters;

    modifying the power spectrum of the LP synthesis filter to convert it from the internal sampling rate S1 to the internal sampling rate S2;

    inverse transforming the modified power spectrum of the LP synthesis filter to determine autocorrelations of the LP synthesis filter at the internal sampling rate S2; and

    using the autocorrelations to compute the LP filter parameters at the internal sampling rate S2; and

    encoding the sound signal encoding parameters into a bitstream; and

    wherein modifying the power spectrum of the LP synthesis filter to convert it from the internal sampling rate S1 to the internal sampling rate S2 comprises;

    if S1 is less than S2, extending the power spectrum of the LP synthesis filter based on a ratio between S1 and S2;

    if S1 is larger than S2, truncating the power spectrum of the LP synthesis filter based on the ratio between S1 and S2.

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