The Parametric Stereo technology is the next major step to enhance the efficiency of audio compression for low bit rate stereo signals. Parametric Stereo is fully standardized in MPEG-4 and the new component within aacPlus v2. As of today, Parametric Stereo is optimized for the range of 16-40 kbps and provides high audio quality at bit rates as low as 24 kbps.

The Parametric Stereo encoder extracts a parametric representation of the stereo image of an audio signal, whereas only a monaural representation of the original signal is encoded in a conventional fashion. The stereo image information is represented as a small amount of high quality parametric stereo information and transmitted along with the monaural signal in the bit stream. Based on the parametric stereo information, the decoder is capable of regenerating the stereo image.

As a result, the perceived audio quality of a low bit rate audio bit stream of e.g. 24 kbps incorporating Parametric Stereo is significantly higher compared to the quality of a similar bit stream without Parametric Stereo.

For more information on the role of the Parametric Stereo technology inside the aacPlus audio codec family, please refer to the aacPlus products page. For more information on licensing, please refer to our licensing page.

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