AEO-light 2 Project Completed

The AEO-light team at the University of South Carolina is pleased to announce the successful conclusion of the grant-funded phase of AEO-light 2. Funded by the National Endowment for the Humanities’ Division of Preservation and Access, the AEO-light 2 project has produced a robust, flexible and open-source software tool to improve the immediate and long term preservation conditions for optically recorded motion picture film soundtracks.

AEO-light two windows image

AEO-light 2 software for capturing optical soundtracks.

 The free software (available for Windows, Macintosh and Linux computers) can be downloaded at the project’s Github code repository site. Video tutorials for its use are at the project’s YouTube Channel.

In the 1920s, film producers began to record synchronized sound to accompany motion pictures. The American film industry’s conversion from “silent” films to “talkies” was rapid once the new technologies proved their worth. Vitaphone ad Movietone were the first film sound products to hit the market. Vitaphone used a separate record player synchronized to a film projector. Movietone recorded its sounds on the motion picture film itself in the form of an optical sound track positioned next to the image portion of the film.

Vitaphone’s “disc” system quickly showed its limitations and optical soundtracks like Movietone became the norm. Throughout the 1930s and 1940s the variety and complexity of optical tracks grew, but the guiding principle underlying the technology was unchanged. Electrical audio signals generated during filmmaking (usually by a microphone) were used to produce varying light impulses, which, in turn, exposed light sensitive motion picture film, creating a visual record of the audio. Once the movie was complete and screened in theaters, the process was reversed. A light in the film projector’s “sound head” was shown through the optical sound track. On the other side of the film strip a light sensitive electric cell converted the changes in the quality and quantity of light falling on it into electrical audio signals that were amplified and push through theater sound systems. Optical sound tracks are still in use today as redundant audio tracks to support digital audio systems where film prints are still run through a projector.

This long, integral history of optical sound makes the documentation and preservation of optical sound technologies critical to the preservation of moving image culture in the 20th century.

AEO-light 2 is a wholly new software solution designed to provide digital audio of high quality for present uses and to create a future-proofing tool to ensure that the audio recorded onto optical sound tracks during the 20th century remain accessible to users in the distant future. Built from the successes and the lessons learned from the AEO-light 1 project (2010-2013), AEO-light 2 reliably generates audio from practically any known optical sound format (e.g., negative or positive, stereo, push-pull).


AEO-light 2 extraction from projection print.


AEO-light 2 extraction from stereo negative track.


AEO-light 2 extraction from camera negative with push-pull noise reduction.

It has been tested in commercial and archival environments and is now included in the Federal Agencies Digitization Guidelines Initiative’s (FADGI) specifications for preservation of motion picture film materials.

The AEO-light 2 team is comprised of Dr. Greg Wilsbacher (principle investigator, Moving Image Research Collections), Dr. Pencho Petrshev (co-PI, Interdisciplinary Mathematics Institute), Tommy Aschenbach (Contributing consultant, President of Video & Film Solutions) and L. Scott Johnson (programmer, Interdisciplinary Mathematics Institute). Additional support for Linux development was provided by Dr. Jason Bakos and Krishna Kalusani (College of Engineering and Computer Science). An amazing Board of Advisors provided support and guidance throughout: Dr. Dimitar Deliyski (Michigan State University), Bob Heiber (President [now retired] of Chace Audio by Deluxe), Ralph Sargent (President [now retired] Film Technologies, Inc.), and Ken Weissman (Supervisor of the Library of Congress’ Film Preservation Laboratory [now retired]).

~Written by Greg Wilsbacher

*This post has been edited with updated videos.

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