Penteo is a digital audio, stereo-to-5.1 surround conversion process based on a mashup

Mashup (web application hybrid)

In Web development, a mashup is a Web page or application that uses and combines data, presentation or functionality from two or more sources to create new services...

 of Avery Lee's open source Center Cut algorithm from VirtualDub

VirtualDub

VirtualDub is a video capture and video processing utility for Microsoft Windows written by Avery Lee.It is designed to process linear video streams, including filtering and recompression...

 combined with Hans Van Zutphen's freeware

Freeware

Freeware is computer software that is available for use at no cost or for an optional fee, but usually with one or more restricted usage rights. Freeware is in contrast to commercial software, which is typically sold for profit, but might be distributed for a business or commercial purpose in the...

 Tape Restore Live azimuth corrector. The process was integrated into a real-time unit and audio remastering service by John Wheeler

John Wheeler (audio/video technologist)

John Henry Wheeler is an audio/video engineer, computer programmer, developer of the Penteo surround-sound process....

 of Berkeley, CA, and now marketed by the company PenteoSurround, Inc.

The process is based on Lee's DSP

Digital signal processing

Digital signal processing is concerned with the representation of discrete time signals by a sequence of numbers or symbols and the processing of these signals. Digital signal processing and analog signal processing are subfields of signal processing...

 cross-correlation

Cross-correlation

In signal processing, cross-correlation is a measure of similarity of two waveforms as a function of a time-lag applied to one of them. This is also known as a sliding dot product or sliding inner-product. It is commonly used for searching a long-duration signal for a shorter, known feature...

 algorithm

Algorithm

In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...

, that parses out individual stereo components that the original mixer channeled to the specific panorama locations of a stereo

STEREO

STEREO is a solar observation mission. Two nearly identical spacecraft were launched into orbits that cause them to respectively pull farther ahead of and fall gradually behind the Earth...

phonic mix.

It was first demonstrated publicly at the Surround Expo in Los Angeles in 2005.

The technology was used extensively on the Watchmen

Watchmen (film)

Watchmen is a 2009 superhero film directed by Zack Snyder and starring Malin Åkerman, Billy Crudup, Matthew Goode, Jackie Earle Haley, Jeffrey Dean Morgan, and Patrick Wilson. It is an adaptation of the comic book of the same name by Alan Moore and Dave Gibbons...

 and Quentin Tarantino

Quentin Tarantino

Quentin Jerome Tarantino is an American film director, screenwriter, producer, cinematographer and actor. In the early 1990s, he began his career as an independent filmmaker with films employing nonlinear storylines and the aestheticization of violence...

's Inglourious Basterds motion picture productions.