Easy datamoshing with Python!
This is a ffglitch wrapper that allows implementing vector motion moshing in python.
Requirements
mosh.py requires ffmpeg to be installed.
vector_motion.py and style_transfer.py depend on ffedit and ffgac, which can be downloaded from ffglitch.org
Effects you can achieve
i-frame removal
This type of glitch creates the transition effect. Example:
| Original | Moshed |
|---|---|
 |
 |
$ python mosh.py input.mp4 -s 40 -e 90 -o output.mp4
removes all the i-frames from the input video starting at frame 40 and ending at frame 90, and outputs the final result
to output.mp4
p-frame duplication
Repeats a series of p-frames (aka delta frames), which can give a 'melting' effect. This type of glitch is triggered by the -d flag. Example:
| Original | Moshed |
|---|---|
 |
 |
$ python mosh.py dog.mp4 -d 5 -s 165 -o moshed_dog.mp4
copies 5 frames starting at frame 165, then replaces all subsequent groups of 5 frames with the copied data (in this case until the video ends, as no -e flag was specified).
Vector motion
While the previous effects copy and delete whole frames, this one changes the actual frame data. As explained in
this article on ffglitch.org, you need to write a custom JavaScript file
that can change the frame data. vector_motion.py is just a wrapper for ffedit and ffgac and makes moshing
possible through only one command.
Example:
$ python vector_motion.py input.mp4 -s your_script.js -o output.mp4
WARNING No matter what name the output file has, it will always be of type mpg (and because we glitched it, video players
will probably have trouble reading its length). To convert it to mp4, you can use ffmpeg:
$ ffmpeg -i input.mpg output.mp4
It will complain about corrupt p-frame data, but the result should look the same as in the mpg.
Vector motion with Python
If you prefer to use python to glitch the frames, you can specify a python script for the -s argument (see previous section for usage).
The script must contain a function called mosh_frames that takes as argument an array of frames (warning: some of the frames
might be empty), where each non-empty frame represents a 3D array of shape (height, width, 2). The function should
return an array of the same shape, representing the modified vectors. For reference, I have included two examples:
horizontal_motion_example.py contains the equivalent python code of the js script from this
ffglitch tutorial.
average_motion_example.py is the equivalent of ffglitch average motion tutorial
using numpy. Neat!
Style transfer
This means combining the motion vectors of two videos, by simply adding them together (see example below). Note that if the videos do not have the same resolution (and framerate), the results might not look as desired.
Examples:
$ python style_transfer.py -e clouds.mp4 -t trees.mp4 output.mp4
extracts vector data from clouds.mp4, transfers it to trees.mp4 and outputs the video to output.mp4.
| Extract style from | Transfer style to | Result |
|---|---|---|
 |
 |
 |
Applying vector data manually
You can also apply already extracted vector motion data, similar to ffglitch:
$ python style_transfer.py -e clouds.mp4 vectors.json
extracts the vector data from clouds.mp4 and outputs it to vectors.json.
$ python style_transfer.py -v vectors.json -t trees.mp4 output.mp4
loads vector data from vectors.json, transfers it to trees.mp4 and outputs the video to output.mp4.