There are basically two kinds of videoconferencing and videophone systems: Dedicated systems have all required components packaged into a single piece of equipment, usually a console with a high quality remote controlled video camera.
These cameras can be controlled at a distance to pan left and right, tilt up and down, and zoom. They became known as PTZ cameras. The console contains all electrical interfaces, the control computer, and the software or hardware-based codec. There are several types of dedicated videoconferencing devices: Large group videoconferencing are non-portable, large, more expensive devices used for large rooms and auditoriums.
Small group videoconferencing are non-portable or portable, smaller, less expensive devices used for small meeting rooms. Individual videoconferencing are usually portable devices, meant for single users, have fixed cameras, microphones and loudspeakers integrated into the console.
Desktop systems are add-ons hardware boards or software codec to normal PCs and laptops, transforming them into videoconferencing devices. A range of different cameras and microphones can be used with the codec, which contains the necessary codec and transmission interfaces. Most of the desktops systems work with the H. WebRTC Platforms are video conferencing solutions that are not resident by using a software application but is available through the standard web browser. Solutions such as Adobe Connect and Cisco WebEX can be accessed by going to a URL sent by the meeting organizer and various degrees of security can be attached to the virtual "room".
Often the user will be required to download a piece of software, called an "Add In" to enable the browser to access the local camera, microphone and establish a connection to the meeting. WebRTC technology doesn't require any software or Add On installation, instead a WebRTC compliant internet browser itself acts as a client to facilitate 1-to-1 and 1-to-many videoconferencing calls.
Videoconferencing modes[ edit ] Videoconferencing systems use two methods to determine which video feed or feeds to display. Continuous Presence simply displays all participants at the same time,  usually with the exception that the viewer either does not see their own feed, or sees their own feed in miniature.
Voice-Activated Switch selectively chooses a feed to display at each endpoint, with the goal of showing the person who is currently speaking. This is done by choosing the feed other than the viewer which has the loudest audio input perhaps with some filtering to avoid switching for very short-lived volume spikes. Often if no remote parties are currently speaking, the feed with the last speaker remains on the screen. Echo cancellation[ edit ] Acoustic echo cancellation AEC is a processing algorithm that uses the knowledge of audio output to monitor audio input and filter from it noises that echo back after some time delay.
If unattended, these echoes can be re-amplified several times, leading to problems including: The remote party hearing their own voice coming back at them usually significantly delayed Strong reverberation , which makes the voice channel useless Howling created by feedback Bandwidth requirements[ edit ] Deutsche Telekom T-View ISDN type videophone meant for home offices and small businesses with a lens cover which can be rotated upward to assure privacy when needed Broadband Internet access Videophones have historically employed a variety of transmission and reception bandwidths, which can be understood as data transmission speeds.
Data transfer rates and live video image quality are related, but are also subject to other factors such as data compression techniques. Some early videophones employed very low data transmission rates with a resulting sketchy video quality. Broadband bandwidth is often called "high-speed", because it usually has a high rate of data transmission. Such devices need to route calls through a Video Communication Server to be able to reach H. In addition, an attractive factor for IP videoconferencing is that it is easier to set up for use along with web conferencing and data collaboration.
These combined technologies enable users to have a richer multimedia environment for live meetings, collaboration and presentations. The organization's vision is to maximize the interoperability of UC based on existing standards.
A number of call-setup methods based on instant messaging protocols such as Skype also now provide video. Another protocol used by videophones is H. Videophones that work on regular phone lines typically use H. A slightly modified version of H. It applied mostly to dedicated circuit-based switched network point-to-point connections of moderate or high bandwidth, such as through the medium-bandwidth ISDN digital phone protocol or a fractionated high bandwidth T1 lines.
Modern products based on H. While additional software is required to patch together multiple video feeds for conference calls or convert between dissimilar video standards, SIP calls between two identical handsets within the same PBX were relatively straightforward. Many in the industry have encountered both types of interfaces, and normally graphical interfaces are encountered on a computer. User interfaces for conferencing have a number of different uses; they can be used for scheduling, setup, and making a videocall.
Through the user interface the administrator is able to control the other three layers of the system. Conference Control performs resource allocation, management and routing.
This layer along with the User Interface creates meetings scheduled or unscheduled or adds and removes participants from a conference. These signals control incoming and outgoing connections as well as session parameters. The Media Plane controls the audio and video mixing and streaming. The RTP and UDP normally carry information such the payload type which is the type of codec, frame rate, video size and many others.
RTCP on the other hand acts as a quality control Protocol for detecting errors during streaming. Multipoint Control Unit Simultaneous videoconferencing among three or more remote points is possible in a hardware-based system by means of a Multipoint Control Unit MCU. This is a bridge that interconnects calls from several sources in a similar way to the audio conference call. There are MCUs which are pure software, and others which are a combination of hardware and software.
An MCU is characterised according to the number of simultaneous calls it can handle, its ability to conduct transposing of data rates and protocols, and features such as Continuous Presence, in which multiple parties can be seen on-screen at once. MCUs can be stand-alone hardware devices, or they can be embedded into dedicated videoconferencing units.
The MCU consists of two logical components: The MC controls the conferencing while it is active on the signaling plane, which is simply where the system manages conferencing creation, endpoint signaling and in-conferencing controls.
This component negotiates parameters with every endpoint in the network and controls conferencing resources. While the MC controls resources and signaling negotiations, the MP operates on the media plane and receives media from each endpoint. The MP generates output streams from each endpoint and redirects the information to other endpoints in the conference. Some systems are capable of multipoint conferencing with no MCU, stand-alone, embedded or otherwise.
These use a standards-based H. The advantages of this technique are that the video and audio will generally be of higher quality because they don't have to be relayed through a central point. Also, users can make ad-hoc multipoint calls without any concern for the availability or control of an MCU.
This added convenience and quality comes at the expense of some increased network bandwidth, because every station must transmit to every other station directly. They can also come with a video recording function to archive past meetings. Please update this article to reflect recent events or newly available information. February A mobile video call between Sweden and Singapore made on a Sony-Ericsson K High speed Internet connectivity has become more widely available at a reasonable cost and the cost of video capture and display technology has decreased.
Consequently, personal videoconferencing systems based on a webcam, personal computer system, software compression and broadband Internet connectivity have become affordable to the general public. Also, the hardware used for this technology has continued to improve in quality, and prices have dropped dramatically.
The availability of freeware often as part of chat programs has made software based videoconferencing accessible to many. The widest deployment of video telephony now occurs in mobile phones. Nearly all mobile phones supporting UMTS networks can work as videophones using their internal cameras, and are able to make video calls wirelessly to other UMTS users in the same country or internationally. Deaf, hard-of-hearing and mute individuals have a particular interest in the development of affordable high-quality videotelephony as a means of communicating with each other in sign language.
Unlike Video Relay Service , which is intended to support communication between a caller using sign language and another party using spoken language, videoconferencing can be used directly between two deaf signers.
Videophones are increasingly used in the provision of telemedicine to the elderly and to those in remote locations, where the ease and convenience of quickly obtaining diagnostic and consultative medical services are readily apparent.
Such units are capable of relaying both regular audiovideo plus medical data over either standard POTS telephone or newer broadband lines. Videotelephony has also been deployed in corporate teleconferencing , also available through the use of public access videoconferencing rooms.
A higher level of videoconferencing that employs advanced telecommunication technologies and high-resolution displays is called telepresence. Today the principles, if not the precise mechanisms of a videophone are employed by many users worldwide in the form of webcam videocalls using personal computers, with inexpensive webcams, microphones and free videocalling Web client programs.
Thus an activity that was disappointing as a separate service has found a niche as a minor feature in software products intended for other purposes.
According to Juniper Research, smartphone videophone users will reach 29 million by globally. In Hall County, Georgia , videoconferencing systems are used for initial court appearances. The systems link jails with court rooms, reducing the expenses and security risks of transporting prisoners to the courtroom.
Social Security Administration SSA , which oversees the world's largest administrative judicial system under its Office of Disability Adjudication and Review ODAR ,  has made extensive use of videoconferencing to conduct hearings at remote locations. This continues the SSA's effort to use video hearings as a means to clear its substantial hearing backlog. Distance education Videoconferencing provides students with the opportunity to learn by participating in two-way communication forums.
Furthermore, teachers and lecturers worldwide can be brought to remote or otherwise isolated educational facilities. Students from diverse communities and backgrounds can come together to learn about one another through practices known as telecollaboration   in foreign language education and virtual exchange , although language barriers will continue to persist.
Such students are able to explore, communicate, analyze and share information and ideas with one another. Through videoconferencing, students can visit other parts of the world to speak with their peers, and visit museums and educational facilities.
Such virtual field trips can provide enriched learning opportunities to students, especially those in geographically isolated locations, and to the economically disadvantaged. Small schools can use these technologies to pool resources and provide courses, such as in foreign languages, which could not otherwise be offered. A few examples of benefits that videoconferencing can provide in campus environments include: