What is a matrix decoder and what does it do?

Question

What is a matrix decoder and what does it do?

Answer 1

If you are talking about audio, it refers to a mechanism for converting a coded stereo audio signal into surround sound by decoding the phase differences in the two channels.

Matrix encoding refers to the encoding of several (usually 4 or 5) channels of sound into a coded stereo signal.

The most well known matrix decoders today include Dolby Prologic and Prologic II, although different brands of A/V receivers often include other matrix decoder formats to process stereo or surround sound into 6 or 7 channels (e.g DTS neo:6, DTS ES).

Answer 2

Simply, it is an audio technology where a finite number of discrete audio channels  are decoded into a larger number of channels when being played back.

For example a stereo signal (2 channel), input into your receiver is manipulated to create more channels.

It gets complicated but many different formats can be created, Dolby Surround, TruHD, Pro logic etc.