EZC3D is an easy to use reader, modifier and writer for C3D format files. It is
written en C++ with proper binders for Python and MATLAB scripting langages.

C3D (http://c3d.org) is a format specifically designed to store biomechanics
data. Hence many biomechanics softwares can produce C3D files in order to share
data. However, there is a lack in the biomechanics community of an easy to use,
free and open source library to read, modify and write them as needed when it
gets to the data analysis.