Video and the Internet
CODECS
Codecs are the technology that allows video to be reduced to a reasonable file size for use on CD-ROMs and the Web.
Codec is an abbreviation for compression/decompression.
A codec can be either a software application or a piece of hardware that processes video through complex algorithms, which compress the file and then decompress it for playback.
CODECS
Unlike other kinds of file-compression packages, codecs decompress the video on the fly, allowing you to view the file from its compressed original.
Codecs work in two ways Temporal and Spatial, both work with "lossy" or eliminating information that is redundant or unnoticeable to the viewer.
Temporal Compression
This method of compression looks for information that is not necessary to the human eye or ear.
It looks at video information frame by frame for changes between frames.
It compares one frame with the next and keeps only the information that has changed.
This reduces the size of the file quite a bit.
If there is a scene change it tags this as a key frame (just as in Flash).
The more key frames, the bigger the file size.
Spatial Compression
Spatial Compression uses a different method to delete information that is common to the entire file.
It also looks for redundant information, but instead of specifying each pixel in an area, it defines that area with coordinates.
Hardware CODECS
Hardware codecs are the most efficient way to compress and decompress video files.
They are faster and require less CPU power than their software counterparts.
Hardware codecs are generally quite expensive, but the results are very good.
Hardware codecs also require the person viewing the file to have the same hardware.
Software CODECS
Software codecs are less expensive and freeware version exist.
The big drawback is that they are CPU intensive.
Architectures
Now we need to discuss how your machine reads that file.
An architecture is a software package that allows information to be traded in a standard format.
Architectures in digital video support file, storage, and playback formats, and allow you to specify which codecs are used.
There are several architectures for Web clients available including QuickTime, VDOLive, and Real Video.