Video Phone Dynamic Images

Video Phone Dynamic images

Video telephony from the concept of technology development to market start, experienced a variety of ups and downs and twists and turns. Especially in China, the video phone market in the long-term thunder, raindrops small situation, the market has yet to start. Very few user terminals after decades of research and development is still basically stay in the book, failed to obtain large-scale application, and video phone is precisely in this unfortunate ranks.

As early as the fifties and sixties of last century, it was suggested that the concept of video phone, that should use the telephone line to transmit voice while transmitting images. In 1964, the United States Bell Labs officially put forward video phone related programs. However, due to the limitations of traditional network and communication technology conditions, video telephony has not made substantial progress. Until the late 1980s, with the chip technology, transmission technology, digital communications, video codec technology and integrated circuit technology continues to develop and become more mature, suitable for commercial and civilian video phone was able to surfaced, to people's vision.

Video phone according to the different image display, divided into static image video phone and dynamic video video phone. The image displayed on the phosphor screen 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 the still picture of the user.

A video telephone 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 is digitized by the large amount of information contained in the video signal and can not be directly transmitted on the subscriber line. The digital image signal needs to be digitized and then the frequency band compression technology , The digital image signal "compression", so that the frequency band narrowed, so that the user line transmission. Motion picture video phone signal is a digital signal, so in the digital network transmission. Video calls can also be added to video equipment, just like a recording phone, the image is 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.