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Teleconference terminal

  • US 5,512,938 A
  • Filed: 03/30/1995
  • Issued: 04/30/1996
  • Est. Priority Date: 04/06/1994
  • Status: Expired due to Fees
First Claim
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1. A teleconference terminal using a personal computer for sending and receiving video code, audio code and data to and from another teleconference terminal, using an ISDN line switching method wherein AV multiframes are defined for an H series recommendation for CCITT, comprising:

  • audio coding means for encoding and compressing an inputted audio signal in accordance with an audio sampling signal, for generating transmission audio code and outputting the transmission audio code to a computer bus, as well as receiving reproduction audio code from the computer bus, and generating a reproduction audio signal by decompressing and decoding the reproduction audio code in accordance with the audio sampling signal;

    video coding means for encoding and compressing an inputted video signal, for generating transmission video code and outputting the transmission video code to the computer bus, as well as receiving reproduction video code from the computer bus, and generating a reproduction video signal by expanding and decoding the reproduction video code;

    AV multiframe conversion means for generating transmission AV multiframes by performing multiplex conversion of the transmission audio code and the transmission video code inputted from the computer bus according to a CCITT recommendation, and outputting the generated transmission AV multiframes to the computer bus;

    transfer means for transmitting the transmission AV multiframes inputted from the computer bus via an ISDN line to the other teleconference terminal, and for receiving reproduction AV multiframes from the other teleconference terminal according to a CCITT recommendation via the ISDN line, and outputting the received reproduction AV multiframes to the computer bus;

    AV separation means for receiving the received reproduction AV multiframes from the computer bus and for separating the reproduction video code and the reproduction audio code from the received reproduction AV multiframes, as well as outputting the reproduction video code and reproduction audio code to the computer bus;

    internal clock supplying means for independently generating an internal clock for the personal computer, as well as supplying the audio sampling signal synchronized with the internal clock to the audio coding means, wherein the audio sampling signal has a frequency of 8 kHz; and

    adjustment means for adjusting surpluses and shortages in the transmission audio code to be included in the transmission AV multiframes, which occur due to synchronization slips between a network clock of the ISDN line and the internal clock, and surpluses and shortages in the reproduction audio code separated from the reproduction AV multiframes, which occur due to synchronization slips between the network clock of the ISDN line and the internal clock.

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