The following is a brief explanation of what video codecs are:
The video codec is the device or software that enables video compression and or decompression for digital video.
Digital video codecs are found in DVD (MPEG-2), VCD (MPEG-1), in emerging satellite and terrestrial broadcast systems, and on the Internet. Online video material is encoded in a variety of codecs:
This codec is used mostly for videos CD’s, and also sometimes used for online video.
This codec is used for videoconferencing, videotelephony, and internet video. H.263 represented a significant step forward in standardized compression capability for progressive scan video. Especially at low bit rates, it could provide a substantial improvement in the bit rate needed to reach a given level of fidelity.
An MPEG standard that can be used for internet, broadcast, and on storage media. It offers improved quality relative to MPEG-2 and the first version of H.263. Its major technical features beyond prior codec standards consisted of object-oriented coding features and a variety of other such features not necessarily intended for improvement of ordinary video coding compression capability.
DivX, Xvid, FFmpeg MPEG-4 and 3ivx
Different implementations of MPEG-4.
Used by Apple's QuickTime, basically the ancestor of H.264. Many of the QuickTime movie trailers found on the web use this codec.
Licensed to Macromedia for use in its Flash Player 6. In the same family as H.263.
WMV (Windows Media Video)
Microsoft's family of video codec designs including WMV 7, WMV 8, and WMV 9. It can do anything from low resolution video for dial up internet users to HDTV. The latest generation of WMV is standardized by SMPTE as the VC-1 standard.
Standardized video compression standard (SMPTE 421M). Based on Microsoft's WMV9 video codec. One of the 3 mandatory video codecs in both HD-DVD and Blu-Ray high-definition optical disc standards.
Hard vs. Soft Codecs
Hard codecs are hardware codecs, normally a computer chip. You supply power and raw video at one end, and get compressed video out the other end in real time. Flip a switch and pump in compressed video, and raw, uncompressed video comes out.
Soft codecs are software modules that do the same thing, such as the DV codecs supplied by QuickTime or Microsoft. Modern computers are fast enough that soft codecs can compress or decompress in real time or even faster.
Both hard and soft codecs provide excellent quality and results if they are used properly.