Codec stands for Coder-Decoder (some say Compressor-Decompressor) and is used to describe anything which turns data into another form for storage or transmission, then changes it back for use.
In
traditional broadcasting, a codec is a physical device which turns
analog video and audio data into digital form to be sent out over the
air. It is also capable of turning received digital information back
into an analog format. In computers, a codec is used as a way of
compressing video, images and audio to a more manageable size. The
majority of codecs use a lossy method of compression, but some are
lossless. Lossless codecs, such as MSU or Huffyuv, reproduce the
original video exactly, with no subsequent loss if the video is
re-encoded. The more common lossy codecs lose varying degrees of
information, but can save substantial amounts of space.
A lossy
codec may be transformative, predictive, or a combination of both. A
transformative codec cuts up the original image(s) or sound and
quantizes it into a more efficient space, then encodes it. A predictive
codec compares a chunk of known data to adjacent data and eliminates
excess information to save size. There are many types of codec
available, each attempting to strike an ideal balance between the loss
of information and file size. Other factors, such as openness and the processor power needed to decode, are also important when considering a codec.
