Compression

Compression is the process of reducing the amount of data and/or the data rate, contained within a digital file. This can apply to any form of data but in this context it refers to digital video and audio files. Usually the amount of data (and its rate) recieved at the sensor of the recording device is greater than that retained in the recorded digital file. This is because the data has been compressed by clever mathematics that, like trigonometry, can have an absence of some the information and still retain the information of the whole. IE some of the information is 'chucked out' and not recorded because the computer within the playback device can 're-create' the missing 'bits'. The more a file is compressed, the more information is chucked out, the mathematics involved becomes more complicated, errors are more likely, and the resulting quality of playback diminishes with greater compression. A particular set of mathematic sums (or algorithms) that is used for a particular compression technique is called a codec. AVR77 is a codec, as is DVcam