Efficient techniques for modifying audio playback rates

  • US 7,664,558 B2
  • Filed: 04/01/2005
  • Issued: 02/16/2010
  • Est. Priority Date: 04/01/2005
  • Status: Active Grant
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First Claim
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1. An audio playback system, comprising:

  • a user interface that enables a user of the audio playback system to specify a selected playback rate SR for an input audio stream that is faster or slower than a normal playback rate NR;

    a memory for storage of at least one rate adjustment parameter, the at least one rate adjustment parameter comprising an overlap frequency OF, wherein the overlap frequency OF is related to the selected playback rate SR;

    a processing device having limited computational resources operatively connected to the user interface and the memory, the processing device being operable to;

    receive the input audio stream associated with the normal playback rate NR,wherein the input audio stream is comprised of a plurality of audio blocks,determine the overlap frequency OF based on the selected playback rate SR;

    generate a modified audio stream for any value of the selected playback rate SR by modifying every Nth audio block of the plurality of audio blocks, wherein N is an integer value corresponding to an integer portion of the overlap frequency OF; and

    an audio output device for outputting the modified audio stream, wherein if the selected playback rate SR is greater than 1.0 and less than 2.0, indicating faster than normal playback, then the overlap frequency OF is equal to 1/(SR−

    1), and if the selected playback rate SR is less than 1.0, indicating slower than normal playback, then the overlap frequency OF is equal to 0.5/((1/SR)−

    1).

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