Video Basics, MPEG-2 Encoder Compression

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.

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.

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-Frameis a full video picture. Because it is likely that a future frame will be similar to a

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