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Method and apparatus for frame accurate access of digital audio-visual information

DC
  • US 5,659,539 A
  • Filed: 07/14/1995
  • Issued: 08/19/1997
  • Est. Priority Date: 07/14/1995
  • Status: Expired due to Term
First Claim
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1. A method for playing at a second presentation rate an audio-visual work that has been digitally encoded in a digital data stream for playback at a first presentation rate, wherein said digital data stream includes a sequence of video frame data, each video frame data in said sequence of video frame data corresponding to a video frame in said audio-visual work, the method comprising the computer-implemented steps of:

  • selecting a selected set of video frames from said audio-visual work based on said second presentation rate;

    constructing a second digital data stream that includes the video frame data that corresponds to each video frame of said selected set of video flames; and

    transmitting said second digital data stream to a decoder;

    wherein said step of selecting said selected set of video flames includes repeatedly performing the steps of;

    determining a bit budget based on a first time value associated with a most recently selected video frame, a second time value associated with a current frame, said second presentation rate and a data transfer rate;

    determining a size of the frame data that corresponds to the current frame;

    if the size of the frame data that corresponds to the current frame exceeds said bit budget, thennot selecting said current frame as a video frame in said selected set of video flames, andselecting a new frame as a new current frame; and

    if the size of the frame data that corresponds to the current frame does not exceed said bit budget, then selecting said current frame as a video frame in said selected set of video frames;

    wherein said step of selecting said selected set of video flames includes the steps of;

    determining whether selection of said current frame would cause said second digital data stream to have a padding rate less than a predetermined padding rate; and

    if selection of said current frame would cause said second digital data stream to have a padding rate less than said predetermined padding rate, then not selecting said current frame as a video frame in said selected set of video flames.

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