Video
A video phone has a video screen and camera for visual output and input. The screen on older designs used cathode ray tubes (CRT) similar to analog TV screens and, as such, was quite bulky. Newer designs have liquid crystal display (LCD) screens and are much smaller. Digital technology has also made the camera, which is usually attached just above or below the screen, more compact in size.
Audio
As two-way audio communication is the original function of the telephone, the traditional handset for audio output and input remains intact. However, the speaker or hands-free mode is a common feature in all video phones (as well as regular telephones) because of the added convenience to the user.
Data Handling
Inside the video phone is a data conversion device. This device enables compression of outgoing video and audio and decompression of incoming video and audio. This device also handles translation of the signal from digital to analog as transmission goes through analog telephone lines.
Bandwidth
Video data create a heavy load to transmit even through a digital telecommunication network. The video quality of a video call depends on bandwidth (i.e., the amount of available data communication resources in the network). Bandwidth, often measured in terms of how fast data can be transmitted, is commonly expressed in kilobits per second (kbps) or megabits per second (Mbps). Networks that can transfer data at a speed of at least 1.5 to 2 Mbps are called broadband. A video call needs a network with this much capacity to be successful.
Data Compression
The video quality of a video call also depends on how efficiently the data are compressed and decompressed. Data compression is essentially a way of encoding information such that it uses the least possible amount of bits--the smallest unit of information. Compressed data are easier to transmit because they take up less network resources. However, for the data to be usable, they must be decompressed once they reach the destination. Because a video call occurs in real time, this process operates simultaneously and must be synchronized for both communicating parties. Efficiency then is largely based on the hardware and the encoding scheme or format used. One of the most recent compression formats utilized by video phones is MPEG-4. MPEG stands for Moving Picture Experts Group, which is the organization that developed this form of data compression.
Tags: video call, output input, quality video, quality video call, This device