Hmm, for MIPS, as far as processing a 48kHz signal, to produce a phantom center would be at most 96,000 integer "add" operations per second, on top of what ever else was going on at the same time. A phantom center requires adding half the center signal to the left and right signals. Halving the center signal is just a bit-shift operation, which on most CPUs is extremely little work. Even if it requires a full "operation," that's still only 144,000 opertions per second, hardly a drop in the bucket when you're talking Millions of OPS.

So I don't think not supporting a phantom center in some modes is a matter of MIPS, I think it's a software oversight. Either someone didn't think to include it, or somebody didn't want to write the code to do it.

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Matthew J. Hill
matt@idsi.net