Video Conferencing
CS461
Summer 1998
- What is Video Conferencing?
- d=>full motion interactive two-way or multi-way broadcasts.
- Point to Point
- Point to Multipoint
- Video Conferencing History
- 1960s-Picture Phone
- 1970s-Full-motion two-way close circuit and one-way noninteractive
- 1980s-Full-motion two-way interactive. Major breakthroughs:
- Video Conferencing Overview (people perspective)
- Increased managerial productivity
- Increased quality of meetings
- Improved quality of life
- Video Conference System Components
- Camera
- Monitors
- Audio
- Control System
- CODEC (CODER/DECODER)
- Communications Link (unchannelized T1, Fractional T1, satellite, microwave, etc.)
- Video Conference System Transmission Technologies
- Microwave
- Satellite
- C-Band
- Ku-Band
- Dishes
- antenna
- low-noise amplifier
- downconverter
- Bandwidth and Compression
- What can be compressed, lowered, or lost?
- Frame rate=> 30 frames per second (FPS) is broadcast quality.
- Luminance=> Light (contrast, brightness)
- Chrominance=> Color (depth of color, hue, saturation)
- Lossless vs. Lossy Compression
- Video Standards
- Px64
- JPEG
- MPEG
- MPEG1
- MPEG2
- Video Conference Standards
- H.320
- H.261
- Multipoint Control Units (MCUs)
- Connecting the Pieces
- Boardroom video conferencing systems
- Typically uses unchannelized T1 for 30 frames per second resolution or fractional T1 (384Kbps) for slightly lower quality.
- All equipment is "fixed" (permanently installed) in a room
- User interface on controller makes using camera presets and other equipment easier
- About $100,000 for all equipment, plus circuit charges per month
- Roll-about video conferencing systems
- System is on highly engineered cart that can be rolled into various rooms for flexibility in scheduling and maximum use of system
- Typically uses fractional T1 (128Kbps) for 15-20 frames per second resolution.
- Cost of system is around $25,000 for equipment, plus circuit charges per month.
- Desktop video conferencing systems
- Can operate over 28.8Kbps dial-up connection up to ISDN and/or LAN connections (4Mbps).
- Equipment ranges from $100 (Connectix Quick-Take) to $1500 (Intel ProShare or PictureTel desktop system) plus connect charges.
- Most systems deliver between 8 and 15 frames per second--relatively low quality video and sound.