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AUDIO DECODER WITH CORE DECODER AND SURROUND DECODER

  • US 20170148450A1
  • Filed: 02/07/2017
  • Published: 05/25/2017
  • Est. Priority Date: 04/16/2004
  • Status: Active Grant
First Claim
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1. A method performed in an audio decoder for reconstructing N audio channels from M audio channels, the method comprising:

  • receiving an encoded audio bitstream, the encoded audio bitstream including a downmixed audio signal and surround data, the downmixed audio signal having M audio channels and the surround data including a set of spatial parameters, the set of spatial parameters including at least one inter-channel intensity difference parameter and at least one inter-channel coherence parameter;

    decoding, in a surround data decoder, the surround data to produce decoded surround data;

    decoding, in a core decoder, the downmixed audio signal having M audio channels to obtain a decoded frequency domain representation of the M audio channels, wherein the decoded frequency domain representation of the M audio channels includes a plurality of frequency bands, and each frequency band includes one or more spectral components;

    reconstructing, in a surround decoder, a frequency domain representation of the N audio channels from the decoded frequency domain representation of the M audio channels, mode information used to select one of a plurality of different mixing schemes, and the decoded surround data; and

    synthesizing, with one or more synthesis filterbanks, the frequency domain representation of the N audio channels to create a time domain representation of the N audio channels;

    wherein M is one or more, M is less than N, the audio decoder is implemented at least in part with hardware, and the reconstructing includes generating a decorrelated signal using an all-pass filter.

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