Video telephone system
First Claim
1. A method for transmitting and receiving video and audio signals over an ordinary telephone line in substantially real time, comprising:
- generating at a transmitting station a video signal having video information;
generating at said transmitting station an audio signal having audio information;
producing a signal wherein said signal includes a mixture of compressed video information and compressed audio information, with said video and audio information being provided to form said signal in a manner that permits accurate restoration thereof at a receiving station and proper synchronization of said video information and said audio information;
modulating said signal;
transmitting said signal after said modulating step using an ordinary telephone line having a limited bandwidth in the range of 300-3,400 Hz;
receiving said signal at a receiving station after having been sent over the ordinary telephone line;
demodulating said signal after said receiving step; and
reproducing said video information and said audio information at the receiving station using said signal.
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Accused Products
Abstract
Apparatus and method are provided for the simultaneous transmission of video information and audio information in substantially real time over an ordinary voice grade telephone line having limited bandwidth in the range of about 300-3400 Hz. Because of the limited bandwidth of the ordinary telephone line, the video and audio information are compressed before transmission thereof. Each of the video information and audio information is separately compressed, mixed together and then further compressed. After the further compression, a composite signal, which includes the mixture of video and audio information, is asynchronously transmitted over the same bandwidth of the ordinary telephone line. Upon reception, the compressed information is expanded and separate video information and audio information are reproduced for viewing and hearing by the receiving party. To reduce the size of the apparatus, application specific integrated circuits (ASICs) are employed. A state machine controller apparatus is integrated with the ASIC technology to control the transfer and storing of video information and audio information and also to control the operation of the various compression and expansion stages associated with the transmitting and receiving channels.
84 Citations
39 Claims
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1. A method for transmitting and receiving video and audio signals over an ordinary telephone line in substantially real time, comprising:
- generating at a transmitting station a video signal having video information;
generating at said transmitting station an audio signal having audio information;
producing a signal wherein said signal includes a mixture of compressed video information and compressed audio information, with said video and audio information being provided to form said signal in a manner that permits accurate restoration thereof at a receiving station and proper synchronization of said video information and said audio information;
modulating said signal;transmitting said signal after said modulating step using an ordinary telephone line having a limited bandwidth in the range of 300-3,400 Hz; receiving said signal at a receiving station after having been sent over the ordinary telephone line; demodulating said signal after said receiving step; and reproducing said video information and said audio information at the receiving station using said signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
- generating at a transmitting station a video signal having video information;
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25. An apparatus for substantially simultaneously transmitting and receiving video and audio signals over an ordinary voice grade telephone line, comprising:
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first means for generating video information; second means for generating audio information; third means for producing compressed video information and compressed audio information for transmission, in substantially real time, over an ordinary voice grade telephone line having a bandwidth in the range of 300-3,400 Hz, and said compressed video information and said compressed audio information being transmitted using the same bandwidth, one of said compressed video information and said compressed audio information being used as real numbers and the other one of said compressed video information and said compressed audio information being used as imaginary numbers, said third means including means for determining a difference between previously transmitted video information and current video information; fourth means for reproducing video information and audio information from said compressed video information and said compressed audio information after transmission thereof; fifth means for displaying images using said video information; and sixth means for generating sounds using said audio information. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
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Specification