FPGA player uses same hardware part as in Super Nintendo game console. It plays .SPC music files stored in flash memory through Sony SPC700 8-bit sound chip. SPC files are more complex than usual mp3 files as they contain so called memory state of SNES sound module. Anyway this is more or less a theory, which you have to study well before start doing something.
The project is developed by using Altera DE2 board equipped with Cyclone II FPGA chip. Hardware part is written with VHDL language. 8 bit microprocessor that executes program is also emulated in software. Seems to be it is very valuable source to study, as project directory can be downloaded freely.