I'm using the Explore EP91H0 chip, because it's the simplest way I could find to add HDMI ARC (that's all the chip does, no video stuff).
What's ARC? "Audio Return Channel". When you plug your amplifier to your TV with an HDMI cable, the TV is able to send audio *back* to the amplifier, despite the TV's HDMI socket being an input (in HDMI parlance the TV is a "sink", and the amplifier is supposedly a "source").
I've also made the schematics a bit modular, using a common sheet for stuff that I expect to be used on most modules (in future I will refine this with further sub-sheets for mandatory / optional bits).