Applications in video conferencing

A video conference system links people at two or more places, letting them see and hear each other in real time using audio, video and data channels.

Components

 Site A                           Site B
 Camera+Mic -> Codec -> Network -> Codec -> Display+Speaker
 Display+Spk <- Codec <- Network <- Codec <- Camera+Mic

• Camera, microphone, display and speakers at each site.
• Codec to compress/decompress audio and video (H.261/H.263/H.264 video, G.711/G.728 audio).
• Network: ISDN, IP network or internet.
• MCU (multipoint control unit) to link three or more sites.
• Software for control, chat and data sharing.

Applications

1. Business meetings: remote teams meet without travel, saving cost and time.
2. Distance education: a teacher at one campus teaches students at several centres.
3. Telemedicine: specialist consultation with a remote patient.
4. Government and courts: remote hearings and meetings between district offices and the capital.
5. Customer support, job interviews and recruitment from different cities or countries.
6. Personal communication: family calls across countries, important for Nepali families with members abroad.
7. Collaborative work: shared whiteboard, screen sharing, joint documents, file transfer.
8. Press conferences and seminars (webinars).

Example: a company with offices in Kathmandu and Pokhara holds its weekly meeting using Zoom. Participants share a presentation and talk, and the meeting is recorded.

Requirements: low delay (under about 150 ms), lip synchronisation of audio and video, adequate bandwidth, and echo cancellation. Audio quality matters more than video quality for understanding.