I have multiple audio devices with optical S/PDIF outputs and want a way not just to switch between them, but being able to have multiple ones enabled at the same time. So while in the process of learning FPGA development I thought it would make a good project to build a digital audio mixer.
It's being implemented on a Altera DE0-Nano FPGA board with an external I/O-board for the S/PDIF transmitters and receivers. It can currently decode samples from the inputs and does some very basic mixing to generate a new sample, however it can't yet generate a new S/PDIF stream. It does however use the on-board LEDs as a level meter, which looks kinda cool :)
When the entire mixing system is working I'll be looking at adding basic DSP-support and expanding the I/O-board with volume controls and level meters per channel.