How to best spec animations/transitions for engineering team handoff

I have an app prototype built using Pixate which demonstrates the entire flow of the app I am working on. There are transitions between views and animations for certain elements on the page. I have shown the prototype to the engineers who are working on the project but they would like a detailed breakdown of what transitions and animations I am using. How would I best communicate these animations in a spec document? Are there any resources or tools to help with animation specs?

(Here is a catch, all of the engineers are using either Linux or Windows machines, whereas I am using a mac. So the solution should be a cross-platform one.)

Since animation is becoming more prevalent in app design, especially in Material Design, I thought this would be an easy question Google search could answer, but no luck. Any help would be amazing. Thank you in advance.

Aaron J.