GHOST IN THE CODEC

Authors: Ryan Maguire and Joselyn McDonald

The Ghost in the Codec was installed at Virginia Tech University. The work demonstrated the concept of what is lost in compression - a visual representation of the standard codec used for MP3s. Visitors to the installation would have their picture taken a computer-based camera. The image would be compressed at the from standard PNG to JPG format. The data that was lost was coded, colored, and printed for the user to see. Participants could keep their copy or hang it on the wall to engage in a participatory collage.

GhostInCodec.jpg

The work was in collaboration with Ryan Maguire, the renowned composer and a leading expert on MP3 compression, who writes more on the Ghost in the MP3 work below:
The MPEG-1 or MPEG-2 Layer III standard, more commonly referred to as MP3, has become a nearly ubiquitous digital audio file format. First published in 1993, this codec implements a lossy compression algorithm based on a perceptual model of human hearing. Listening tests, primarily designed by and for western-european men, and using the music they liked, were used to refine the encoder. These tests determined which sounds were perceptually important and which could be erased or altered, ostensibly without being noticed. What are these lost sounds? Are they sounds which human ears can not hear in their original context due to universal perceptual limitations or are they simply encoding detritus? It is commonly accepted that MP3's create audible artifacts such as pre-echo, but what does the music which this codec deletes sound like? In the work presented here, techniques are considered and developed to recover these lost sounds, the ghosts in the MP3, and reformulate these sounds as art.