VBrick Systems VB6000 Series, Руководство по началу работы

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VBrick Appliance Getting Started Guide 17
Chapter 4
Streaming Video Basics
Topics in this chapter
Video Basics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Getting the Best Video . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Network Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Typical Applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
VBrick Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Serial Port Passthrough . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
MPEG Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
WM Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Video Basics
It is important that the source of the video to be encoded and networked be of the highest
possible quality in order to avoid using unnecessary bandwidth to transport source video
artifacts, distortion, etc. If using a camera, exercise common sense; good lighting and a steady
camera will improve overall performance. Cameras, VCR tape players, DVD players, and live
television broadcast feeds from a TV tuner can all be used as video sources. VBrick supports
standard video via BNC connectors, or S-Video via mini-DIN connectors. BNC-to-RCA
adapters are readily available if RCA type cables are used.
MPEG-2
MPEG-2 (Moving Picture Experts Group) is a standard method of transmitting digital video
and sound in a compressed format that uses less bandwidth than the traditional analog
method. MPEG-2 is the de-facto standard in the digital TV world. MPEG-2 gives high
resolution, scalability and handling of interlaced video for digital video above approximately
2 Mbps. It allows for an excellent picture and allows multiple channels at various bit rates to
be multiplexed into a single data stream. It was officially adopted by ISO and has the catalog
number ISO 13818-1.
MPEG-2 Encoder Compression
Understanding I, B, P Frames, Delay, and Synchronization
In compressed video, each frame is compressed using a "lossy" compression scheme that
takes advantage of the fact that the human eye does not detect certain types of visual
information loss. MPEG compresses files based on I, B, P frames, which contain information
from previous pictures and predictions about future pictures in a Group of Pictures (GOP).
An
I-Frame is a full video picture. Because it is likely that a future frame will be similar to a
Note Where possible VBrick recommends using S-Video or optional SDI. S-Video output
from the VBrick to S-Video Input on the monitor yields the best video quality and the
Billboard, Program and Conference Guides will be much clearer.