Are there instructions available how to compile Xvid with my compiler?
Have a look at the install readme file that comes along with Xvid. It describes how to use the Xvid build scripts to compile Xvid with gcc under Linux or MinGW/CygWin. Xvid can also be compiled with Microsoft Visual C++ compiler using the provided project files included in the build directory. For other compilers youre pretty much on your own. It should be not very difficult however to make the code compile with a different compiler.
