From Hydrogenaudio Knowledgebase
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| ''Information <u>adapted</u> from [http://en.wikipedia.org/wiki/Parametric_stereo wikipedia]''
| | #REDIRECT [[Joint stereo#Parametric stereo]] |
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| '''Parametric stereo''' is a feature used in [[AAC]] to further enhance efficiency in low bandwidth stereo media. It, along with [[SBR]], is part of '''[[aacPlus]] v2''', and MPEG-4 HE-AACv2.
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| Parametric stereo works by taking the two mono streams that make up a stereo stream and combining them together to form a new single mono audio stream, but 2-3 kbit/s of side info (the parametric stereo) is also recorded. By having the parametric stereo side info along with the mono audio stream, the decoder (player) can '''approximate''' the original stereo. | |
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| Because only one real audio signal is sent, along with the negligible side info, a 24 kbit/s stereo stream of audio and a 24 kbit/s stream of audio with parametric stereo will be drastically different in quality. This can be modeled as:
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| :12 kbit/s mono + 12 kbit/s mono = 24 kbit/s
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| But, with parametric stereo:
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| :22 kbit/s mono + 2 kbit/s PS side info = 24 kbit/s
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| This makes the overall sound quality sound like a 22 kbit/s per channel piece of audio, rather than a 12 kbit/s piece of audio. That's 10 kbit/s more per channel, making the comparison more like:
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| :24 kbit/s vs. 44 kbit/s
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| for the same amount of data.
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| ==External link==
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| * [http://www.codingtechnologies.com/products/paraSter.htm Parametric Stereo at Coding Technologies]
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| [[Category:Technical]]
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| [[Category:Algorithms]]
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Latest revision as of 05:26, 16 July 2023
