Penteo
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Penteo® is the registered trademark for a process developed by John Wheeler of Berkeley, CA for professionally upconverting stereo to surround sound (stereo upmixing) using a Fast Hartley Transform followed by a coorelation algorithm and an artifact scavenger. The process is able to cleanly recover stereo sounds that the original mixer sent to the left, center, right of a stereophonic mix, with discrete separation between the channels. Those channels can then be re-collated with the original stereo mix to create a surround environment based on the original stereo mixer's stereo panorama choices.
Unlike other attempts to upconvert existing stereo recordings, the Penteo process starts with a complete remastering of the original stereo source, bringing the left and right channels into absolute synchronization (micro-azimuth error correction) and balance (within .2 db) so that the upconverting algorithm has a perfected master from which to work. It is a painstaking manual process which has to compensate for physical tape damage, splices, and recording-deck mis-alignment. For this reason, the Penteo process can only be applied at the mastering level by an engineer in a mastering lab.
It is designed to produce professional 5.1 masters which can then be mass-produced or incorporated into motion picture soundtrack production.
It was first demonstrated publicly at the Surround Expo in Los Angeles in 2005. It is being used extensively for production of classic rock surround source material for the HD Radio surround broadcast program at WZLX Boston.
