Just received a 9.1.4 file from the 2L record label. When I play this on my 7.1.4 system, MC says "Convert from 14 channels to 7.1.4 channels." This is fine, but I don't know what it's doing. Technically I know that channels 5 and 6 in the file are supposed to be phantom between the front L and side L and front R and side R respectively for a 7.1.4 system (straight from the recording engineer).
Question: What is MC doing in this conversion?