Parametric stereo

Parametric stereo (abbreviated as PS) is an audio compression algorithm used as an audio coding format for digital audio. It is considered an Audio Object Type of MPEG-4 Part 3 (MPEG-4 Audio) that serves to enhance the coding efficiency of low bandwidth stereo audio media. Parametric Stereo digitally codes a stereo audio signal by storing the audio as monaural alongside a small amount of extra information. This extra information (defined as "parametric overhead") describes how the monaural signal will behave across both stereo channels, which allows for the signal to exist in true stereo upon playback.