Write a C++ commandline application that encodes a set of WAV files to MP3

This was a takehome excercise from a job interview.

Requirements:

• call application with path to folder as argument
• use all cpu cores
• statically link libmp3lame
• should compile and run on linux and windows
• ignore non-wav files
• portable multithread (pthread?)
• no frameworks such as boost or qt
• reasonable standard settings

Build

• the libmp3lame.a in lib/ was compiled on linux with ./configure --disable-shared --enable-static --disable-frontend.
• at least on linux this builds by running cmake CMakeLists.txt followed by make
• I'm not good with c++ build tools so I know this is pretty scuffed
• havent put much thought into the settings
• should have done some error checking. non wav files with a .wav ending would probably cause this to crash