I followed MlNDBOMB's guide on installing MPC-HC, LAV, and madVR. (thanks!) I'm upgrading from DVD to Blu-ray, so everything looks and sounds amazing to me. Almost.
My problem is with movies encoded with 5.1 PCM (e.g. Chicago, Cars). My receiver says it's receiving 7.1 channels of audio, so it doesn't expand the 5.1 to 7.1. The surround audio comes out my rear speakers, and my side speakers have nothing.
I don't know if the problem is with MPC-HC, LAV, the Nvidia drivers, or something else. Dolby and DTS movies play fine (I set them to bitstream).
How do I tell my HTPC to output 5.1 channels when it's playing a PCM 5.1 movie (and 7.1 channels for 7.1 movies)?