Compression = Video takes up a lot of space. Uncompressed footage from a camcorder takes up about 17MB per second of video. Because it takes up so much space, video must be compressed before it is put on the web. “Compressed” means that the information is packed into a smaller space. There are two kinds of compression: lossy and lossless.
Lossy compression = Lossy compression means that the compressed file has less data in it than the original file. In some cases this means lower quality files, because information has been “lost,” hence the name. However, a relatively large amount of data is lost before being noticed as a difference by the human eye. Lossy compression makes up for the loss in quality by producing comparatively small files. For example, DVDs are compressed using the MPEG-2 format, which can make files 15 to 30 times smaller.
Lossless compression = Lossless compression is compression where none of the information is lost. This is not as useful because files often end up being the same size as they were before compression. This may seem pointless, as reducing the file size is the primary goal of compression. However, if file size is not an issue, using lossless compression will result in a perfect-quality picture. For example, transferring files from one computer to another using a hard drive might choose to use lossless compression to keep the quality.
Codecs = Codec is a short name for coder-decoder, the software that takes a raw data file and turns it into a compressed file. Because compressed files only contain some of the data found in the original file, the codec is the “translator” that decides what data makes it in to the compressed version and what data gets discarded.
Different codecs translate in different ways, so a video file compressed using the Intel Indeo codec will be different from a file compressed using the Cinepak codec, for example. Sometimes the difference is noticeable, sometimes not, such examples consist of codecs codes like MP4, MPEG, h.264 (used the most) etc.
This is the preferred method of transmitting Flash video over the web and can be seen at YouTube, Google Video, MySpace, and almost any other video-enabled social video networking site.
What colour saturation does = removes the colour therefore the image becomes black and white
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