The m_iSelection array could probably be made unsigned... IF we were
confident we never try to assign it a negative number, of which fact I'm
not convinced.
JACK processes every channel separately, so we need this. The audio data is
interlaced all the way back at RageSound::GetDataToPlay(), so this is an easier
hack for now than using deinterlaced until it's needed.
Devin J. Pohly