ARTIFACTS



"Whatever you now find weird, ugly, uncomfortable and nasty about a new medium will surely become its signature. CD distortion, the jitteriness of digital video, the crap sound of 8-bit - all of these will be cherished and emulated as soon as they can be avoided. It’s the sound of failure: so much modern art is the sound of things going out of control, of a medium pushing to its limits and breaking apart. The distorted guitar sound is the sound of something too loud for the medium supposed to carry it. The blues singer with the cracked voice is the sound of an emotional cry too powerful for the throat that releases it. The excitement of grainy film, of bleached-out black and white, is the excitement of witnessing events too momentous for the medium assigned to record them." - Brian Eno (1996)
......................................................................................................................................................

Every medium imprints itself on the subject it represents. For this activity, we will look closely at a one of today's most common digital compression techniques. We will analyze the artifacts it leaves in its wake and, like archaeologists, pull those artifacts to the video surface.

1) Download and install FFMEGX and AVIDEMUX

2) Open FFmpegX and install the binaries.
- Set the video codec to Xvid avi. Keep the video bitrate high (20000 is high) and make sure video parameters are all consistent between different video clips. Set the keyframe interval to a HUGE number (999999999). This increases the number of P frames in our video. ENCODE.

3) Open avidemux
Open your first clip. Import your second clip by choosing file > append. Use the double arrows to skip between I-frames and set 'in-point' and 'out-point' around all the I-frames except the first one. Choose edit > delete. SAVE YOUR VIDEO (be sure to manually include the file extension '.avi')

note: if your computer doesn't play the final video, bring it back into FFmpegX and re-export it in a more stable format.
......................................................................................................................................................

AN EXPLANATION OF THIS PROCESS
A digitally-encoded video is not like a film. It isn't a sequence of still images. In fact it only contains a few full-image frames. These are called I-frames. The rest of the frames are encoded as the change between different frames. These are called P-frames. The P-frame contain data that represents changes in color, movement, etc. When you remove I-frames you remove the reference points for the codec, so when you play your altered video the movie player recalculates the moving image based on assumptions that we have broken down. By removing these reference points the codec's assumptions are now wrong and we get this distinctly digital effect.
......................................................................................................................................................

VOCABULARY:
-I‑FRAME- An 'Intra-coded picture' is like a conventional static image file.
-P‑FRAME- A 'Predicted picture' holds only the changes in the image from the previous frame.
-CODEC- An algorithm capable of encoding and/or decoding a digital data stream. The word codec is a  blending of 2 words: 'compressor-decompressor'.
-COMPRESSION ARTIFACT- A noticeable error that is the result of data compression. It is often the result of an incorrectly determined data compression scheme.
-GLITCH ART-  the aestheticization of digital or analog errors.

-->NEXT TOPIC-->