(clip A) I - P - B - P - B - P - (clip B) I - P - B - P - B - P - B (clip A) I - P - P - P - P - P - (clip B) I - P - P - P - P - P - P These can be used to create datamoshing effects also, but the effects are less predictable so I'll leave that up to you to experiment with.)įollowing are some examples of normal frame structures. (note: There are also B-frames, these are similar to P-frames but a B-frame references both the frame before AND after itself. This is their attraction for video compression codecs: the higher the P-frame to I-frame ratio the smaller the file size. Naturally, P-frames contain less data than I-frames, so they take up less memory. Thus, only areas of motion or changing luminance values are described in a P-frame, making them more like a set of instructions than an image. P-frames, on the other hand, are reference files that inform the video player of changes in the image since the previous frame. Effectively, they are still images containing all the color and luminance information of that frame.
I-frames (also referred to as keyframes) are full representations of a single frame of the video. Digital video files are made up of sequences of different types of frames. To understand datamoshing, you need to know about I- and P-frames. Regardless, it recently hit the mainstream in the form of music videos for Chairlift and Kanye West, so there has been a lot of digital press on the subject. It seems likely that someone was doing this before 2005, after all, there were poorly compressed DVD rips to inspire them. The effect has been in use by digital media artists since at least 2005, though exactly when it was first produced intentionally is a matter of some debate. If you've ever skipped ahead in a poorly compressed DVD rip and seen the moving outlines of actors ghosted behind the pixels of the scene you were just watching then you know what I'm talking about. Datamoshing, as it has been coined by the Providence, RI / Pittsburg, PA artist collective Paper Rad (warning, site may induce seizures), refers to a technique of exploiting video compression to create intentional artifacting and distortion.
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