How to datamosh a video

The fast way: MOSH_UNIT (Windows)

MOSH_UNIT is a standalone app built only for this. It runs on 64-bit Windows 10 and 11, works completely offline, and costs $7.99 as a one-time purchase. The four steps below are the whole workflow.

1. 1

   Import your clip

   Open MOSH_UNIT and drag a video onto the timeline. It reads MP4, MOV, AVI, MKV, WebM and more through the bundled FFmpeg, so there is nothing to convert first.

2. 2

   Draw the effect

   Pick an effect (Bloom, Freeze, Reverse or Shuffle) and draw across the clip where it should hit. You paint the glitch on directly, no keyframes.

3. 3

   Stack and preview

   Stack more effects onto the same zone and reorder them, then press preview to watch the glitch render. Reordering the stack changes the result.

4. 4

   Export an MP4

   Export the result as an MP4 at highest quality. Your original audio is kept and stutters along with the effects, so picture and sound stay in sync.

The free way: Avidemux or ffmpeg

You can datamosh for free if you are comfortable with codecs. The idea is always the same: encode to a format with sparse keyframes, then remove or repeat frames.

• Re-encode your clip to an interframe codec (for example Xvid in an AVI) so it has long gaps between keyframes.
• In Avidemux, use copy mode and delete the I-frames (keyframes) where you want the melt to begin.
• To bloom instead, duplicate P-frames so a single motion repeats and pumps.
• Save, then re-encode to MP4 for sharing. Expect trial and error: some clips mosh beautifully, others barely react.

ffmpeg can do the same from the command line and is fully scriptable, but there is no visual feedback until you play the output.

The After Effects way

After Effects can produce datamosh looks with a paid plugin or with manual frame work, but it needs an Adobe subscription and a real learning curve. If you already live in After Effects it is an option; if you just want the look, it is the slow road.

Fast vs free, at a glance