lossless

Digital media has been forced by the constraints of media and hardware into new representational strategies. Example: a 100 minute Hollywood film is composed of 144,000 discrete 35 mm frames plus two or more tracks of audio track. Scanning these frames at “2k” (which is on the low end of a scan meant for standard definition) results in something like 1.7 terabytes of data (assuming 12 megabytes of data per uncompressed frame). The best lossless techniques reduces that number to about 400 digital video disks (DVDs). How do you reduce the data to 1/400 of the data contained in a 35mm film print?

1. Start by tossing out color that we can't see–this is prejudicing the information towards the sweet spots of our perceptual kit. This is a branch of psychology called psychophysics and results in lossy compression.

2. Now describe the image as instructions for reconstituting each compressed frame. Example: A solid black frame may be described as the color black painted over every pixel. Call this an algorithm for reconstituting each frame. This is a true lossless compression called Run Length Encoding (RLE). There are many variation on RLE. Note that this compression is lossless.

These two strategies gets your data down to maybe forty disks. That's a reduction by a factor of ten, leaving another factor of ten to go. What else may be done to reduce the data and still have a recognizable image?

3. Try a hybrid approach combining the approaches of 1. and 2. Apply the perceptual approach and spatial approach over time. If a pixel doesn't need updating over time then tell it to stay the same as it was in the last frame. That creates temporal streams of colors that we don't notice because they're not changing. Be sure to update the whole frame every two seconds or so and you have a pretty good image that fits on a DVD.

The combination of color reduction and spatial & temporal RLE is radically different from the flickering sequence of 24 still 35mm film frames projected on a screen. Digital media is constrained picture and sound data ¹⁾ sent as instructions to a graphics chip and projector which result in a performance of light and color. This results in what we call a phenomenology of digital media.

We like the way that this relates to the material manipulations of light and sound that brakhage et alia promote. This provides another link to the aesthetic phenomenologies discussed in the canon of experimental film.