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created with moshy's pdupe options

moshy is a command line datamoshing utility kit for AVI files, based heavily on aviglitch. It's designed to make common datamoshing tasks easier without having to open avidemux or other GUI tools. It lets you do stuff like:

  • Convert video files into AVI video files with minimal I-Frames and no B-frames for ultimate moshability
  • Create P-Frame duplication effects quickly
  • Split a long video file into multiple clips based on its I-Frames
  • "Bake" your datamoshed video, encoding the corruption as actual video content for uploading to video services or moshing even further!
  • Identifying keyframe and deltaframe indexes in any AVI file
  • ...and more!

If you don't know how to use the command line, this is a great opportunity to learn:

Get it!

You'll need to install Ruby. If you're on Mac OS X, you probably already have a local version of Ruby installed. Once that's done, you can use Rubygems (which comes with Ruby) to install moshy:

gem install moshy

From there, you can use moshy from the command line.

For a couple commands (prep and bake), you need to have ffmpeg installed locally. You can get it for your OS here.

What's it do?

Moshy currently has six different modes:

  • prep - Preps a video file for datamoshing with moshy by converting it into an AVI with no B-Frames (they're not good for moshing), and placing as few I-Frames as possible. Requires ffmpeg be installed locally.
  • isplit - Extracts individual clips from an AVI where each clip is separated by I-frames in the original AVI. Great for getting specific clips out of a larger video and later doing I-frame moshing.
  • inspect - Reads an .avi file and prints which video frames are keyframes (I-Frames) and which frames are delta frames (P-frames or B-frames). moshy cannot tell the difference between a P-frame or a B-frame, so you will want to use avidemux or another program if you need to know.
  • pdupe - Duplicates a P-frame at a given frame a certain amount. To find out which frames are P-frames, use software like avidemux to look at the frame type. WARNING: This mode is a little glitchy. You may need to set the interval 1 or 2 above or below the frame number you actually want to duplicate. I'm not sure why this happens, but try it with a small duplication amount first. NOTE: This can mode take a while to process over 60-90 frame dupes.
  • ppulse - Takes c number of frames and every n frames and duplicates them a given amount, resulting in a consistent P-duplication datamosh that's good for creating rhythmic effects. This was originally created to create mosh effects in sync with a beat for a music video.
  • bake - "Bakes" your datamosh by creating a new video file from your datamoshed .avi, causing the datamosh effects to be treated as the actual content of the new video instead of an error. Requires ffmpeg to be installed locally.

You can access detailed info on how to use each of them from the command line with the command moshy -m <mode> --help.


If you think this is cool, you'll probably find my list of glitch art resources useful as well as the Glitchet newsletter, a free weekly futuristic news and glitch aesthetic e-zine.

Quick tutorial

Here's a short example of how you might use moshy to create a P-dupe mosh:

  1. Choose a YouTube video you want to mosh (I'll use "Charlie bit my finger":
  2. Download it with KeepVid (
  3. "Prep" it with moshy to turn it into an .AVI with minimal I-Frames and all P-frames (because B-frames don't mosh well):
    moshy -m prep -i charlie.mp4 -o charlie.avi
  4. Open charlie.avi in avidemux and clip it down to the segment I want (moshy will soon be able to do this with a "clip" command):
  5. Open charlie_clip.avi and find the frame I want to P-dupe mosh (here, frame 196):
  6. Use moshy in pdupe mode to dupe frame 196 60 times:
    moshy -m pdupe -i charlie_clip.avi -f 196 -d 60 -o charlie_clip-dupe.avi
    Open it in a video player (I use VLC) and see if it looks good.
  7. Awesome, I love it, but I want to clip it down to size. However, since it has so few I-frames, if I just clip it anywhere, the beginning of the video will become corrupted because of lack of pixel data. Let's use moshy to bake the mosh:
    moshy -m bake -i charlie_clip-dupe.avi -o charlie_clip-dupe-bake.avi
  8. Done. Let's open it back up in avidemux, clip it down to size, and save our final result:
  9. Looks good to me. Let's save it as an MP4 so that I can upload it to Giphy, which will convert it into a .gif for me. (I'm hoping to add modes to moshy that convert videos to .gif and .mp4 directly, too.)
  10. Done!


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