Tuesday, March 04, 2008

5 Important Video Codecs You Must Know

A video codec is a 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.

Below are 5 Must Know Video Codecs and their features

1. H.263 – use for video conferencing
This codec is a good choice for the business community. It’s ideal for a video conference where you do not need high-quality pictures and where audio is going to take priority. It is best with low movement films, so a more or less stationary talking head is going to be just perfect. The data rate for thiswould be small, but much quality is lost. Perhaps the only use of this codec is if you wanted to send aquick version of a film for viewing by a co-worker; you may not worry too much about the way it looksas you just want quick feedback.

2. Cinepak – use for CD-ROMs
This is a good, well-established system which works best with small image sizes. This codec is outperformed by many others, even though its small picture size, at 120x90 pixels, is now getting bigger as computers improve. It is better used on low-end machines but is not usually the first option for web film, being more suited to CD-ROMs. A big advantage with this codec is that it allows the sender to customize settings throughout a film, so you can apply heavier compression to places where there is notmuch movement but lighter compression to where you need more detail on screen, perhaps during anaction sequence. This process avoids ‘data spikes’, where sudden increases in data cause a movie to stopplaying on the user’s PC because too much data is needed.

3. RealG2 – good for web work, not for other uses
This codec is widely used on the web. It uses ‘temporal scaleability’, which means that the result forthe user is smoother than others even on a wide range of computers or devices. This means movies encoded with it play at a high frame rate for fast processors and low for slow ones. This codec is hard to beat in terms of the number of users who may have access to it on the web and the ease with which the rest can download it (for free).

4. Sorenson – good all-rounder
This is a really good, high-quality codec and looks better than most at a screen size of 320x240. It’sa good solution for movies that are going to be viewed over broadband connections, but some editions (notably the Developer Edition) cater for the other users by enabling scaleable streaming. One aspect which puts many people off using this codec is the length of time it takes to encode a movie in this way,but it remains the method of choice for most short movies, for the web and CD.

5. Intel Indeo 4 and 5 – good, but mainly for high power
With this method of compression you get a good result with high picture quality, but it is only viablefor high-powered PCs or Macs. Version 5 allows for progressive downloads. Intel’s codec is generally better than Cinepak, but cannot match the picture quality of the Sorenson.

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