Videoconferencing Technology

Image quality : Better image quality means more realistic conferences, with every participant clearly visible. Ultimately, subjective quality is limited by resolution a measure of the number of pixels making up a picture. For comparison, a modern notebook PC screen can offer a resolution of 1024 x 768 or even higher. Higher image resolutions also allow documents and diagrams from a connected computer to be seen more clearly by other conference participants but higher resolutions demand higher data rates. Sony systems such as the PCS-G70NP support video image qualities as high as 4CIF roughly equivalent to standard definition television broadcasts

Frame Rates: the number of images displayed per second has a dramatic effect on the quality and intelligibility of any videoconference. Low-cost webcam systems are often limited to just a few frames per second. This results in jerky, unnatural looking pictures that can be a distraction during a conference, particularly when the picture isn't smoothly synchronised with what the speaker is saying.

Using latest coding methods, Sony systems such as the PCS-G70NP support frame rates of up to 30 fps, or up to 50 interlaced fields (alternately scanned half frames) per second. Sony uses a range of QoS features including Real-time ARQ (Automatic Repeat reQuest), ARC (Adaptive Rate Control) and FEC (Forward Error Correction) to optimise frames rates plus audio quality under a wide range of real-world network conditions

Compression formats: All videoconferencing systems send video and audio across IP network connections or ISDN phone links as a stream of digitised data. There are several internationally-agreed standards for compressing data to deliver optimum sound and picture quality for a given bit-rate. The high efficiency of current standards such as H.264 now enables the transmission of high quality video and high bandwidth audio right up to High Definition

QOS: Frozen picture frames and annoying audio glitches: they're symptomatic of lost or degraded data packets sent over IP networks. It's a common problem, and congested networks or limited bandwidth can seriously impair the Quality of Service (QoS) enjoyed by videoconferencing users. Sony PCS Series videoconferencing systems use a range of QoS features including Real-time ARQ, ARC and FEC to optimise audio and picture quality under a wide range of real-world network conditions