At ((25fps - 1 i-frame)) * 15 or (24 * 15) a single second of 24 frames turns into 360 frames which is (360 frames / 25 fps) = 14.4 seconds.Īfter we’re done mucking around with i-frames and p-frames the results are fed to ffmpeg which locks in the glitches and makes a twitter-ready video. So that’s what the repeat_p_frames variable does and that’s why “it sounds like a dying printer”- Because we’re repeating p-frames the video length may get much longer. However the glitchers eventually grew bored of this and discovered if they repeated p-frames that the calculations would cause a blooming effect and the results were real rowdy. Initially datamoshing was just deleting the extra i-frames maybe smooshing some p-frames in from another video and seeing what you got. The encoding algorithm then makes inter-frame calculations and sometimes interesting effects happen. The first i-frame is the only one that’s required and after that we use p-frames to calculate from frame to frame. A video can be entirely i-frames but the file size is much larger than setting an i-frame every 10 or 20 frames and making the rest p-frames. I-frames (aka key frames) give a full frame’s worth of information while p-frames are used to calculate the difference from frame to frame and avoid storing lots of redundant frame information. There are 2 types of frames that we’re dealing with: i-frames and p-frames. What’s happening in the Python datamosh tool is that first the video file is converted to AVI format which is glitch friendly as it sort-of doesn’t care if you delete frames from the middle willy-nilly (mp4 gets real mad if you delete stuff in a video file). We datamosh because we can, and because it looks really cool. In plain English, datamoshing is an umbrella term for an array of cool effects you get by glitching, altering, or otherwise breaking the fundamental structure of video files’ data. There’s no decent datamoshing addon written yet, and I think this could be interesting for a lot of people in the oF community. The Python tool already needs some maintenance (found some broken stuff), and I thought it would be a nice exercise (C++, Python) to refactor the “ you-can-datamosh-on-linux ” as an openFrameworks addon.

The Python script also has the algorithm to edit i-frames and p-frames. Ffmpeg is used for the video format conversion. It is basically a Python script that wraps around the famous ffmpeg, a vast software tool suite of libraries and programs for handling video, audio, and other multimedia files and streams. I could only find one single datamoshing tool that is able to run on Linux: I was reading about datamoshing and fell in love with it.

Video datamoshing