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Because multimedia typically derives from data sampled by a device such as a camera or a microphone, and because such data contains large amounts of random noise, traditional lossless compression algorithms tend to do a poor job compressing multimedia. Multimedia compression algorithms, traditionally known as codecs, work in a lossy fashion:

1. Transform the data according to a model designed to reduce sample-to-sample correlation, concentrating the important signal in a few data values.
2. Quantize the data, most of which has become noise. Some codecs use a scalar quantizer followed by run-length encoding; others use vector quantization.
3. Use entropy coding such as Huffman coding to reduce the number of bits that the most common values use.

This method is called transform coding.

Multimedia compression has become the primary focus of compression research, primarily in a search for more efficient models. It is the most important part in video coding formats.

See also:

• Video compression
• Audio compression
• General data compression
• Digital signal processingDigital signal processing DSP is the study of signals in a digital representation and the processing methods of these signals. DSP and analog signal processing are subsets of signal processing. It has three major subfields: audio signal processing, digita