The basic function of video phone
Video phone can also join the video equipment, like recording the same phone, the image recorded in order to retain. Still images Video telephones are now available on public telephone networks, while motion picture video telephony has not been widely used because of the high cost. But it is expected that with the development of microelectronics technology, the extensive use of large-scale, very large scale integrated circuits, and the rapid development of integrated services digital network, dynamic video video phone will play an important role in future communications.
A video phone device can be used as a regular telephone to access the public telephone network. The dynamic image video phone displays the image that is active, and the user can see each other's smiling or talking image. The image signal of the moving picture video telephone has a large amount of information and can not be transmitted directly on the user line. It is necessary to digitize the original image signal into a digital image signal, and then it is necessary to use the band compression technique , The digital image signal "compression", so that the frequency band narrowed, so that the user line can be transmitted. Motion picture video phone signal is a digital signal, so in the digital network transmission.
The image is still, the image signal and the voice signal are alternately transmitted using the existing analog telephone system, that is, the picture can not be transmitted when the image is transmitted; it takes 5-10 seconds to transmit a half picture of the user's half body.
