How to produce glitch effects I wonder how one could produce animated video glitch effects, like digital codec or connection problems or even analog cable problems.

I wonder how one could do something that can work on top of a video (to displace parts of it, mess up the colors in rectangular areas, create different noise patterns etc).

Reference 1:
This movie poster, even though completely static, has very nice blocky artifacts. That are dependant on input image (the photo):
http://www.motionelements.com/stock-video-8919500-noise-glitch-video-damage



Reference 2:
(follow the link and watch video demos)
http://www.motionelements.com/stock-video-8919500-noise-glitch-video-damage

What can I do to achieve similar effects?
I used particles with refraction shader, with random rotation in Global Y axis.

The particles were rectangular planes, and their material used the "Object info > Random" value to randomize what each particle does.

I used Math > Multiply and Modulo to vary the randomized value into multiple different values to change the IOR for Refract shaders, optionally use some stretched noise texture for bump-map to add extra horizontal stripes.

It uses an orthogonal camera that looks down at a textured plane - whatever you put as a texture on that plane will be the source image or video.

Result: https://youtu.be/m-h_f6KX-dw