I need an mp3 decoder, for windows and mac os x, I own IPP 6, but it seems that UMC has been deprecated (??) and is not available for OSX 64-bit, so the alternative is "Media SDK", but:
"Media SDK for Windows* - A cross-platform API for developing media apps (foundation)." - What on earth is that? Is it crossplatform then or is it not? Is it available for OSX 32 & 64?
I'm sorry to say but INDE Media SDK and INDE Audio are not supported on OSX. Cross platform actually mostly means cross HW platform. Also, there are Media SDK and Audio libraries for Linux (within Intel Media Server Studio). But nothing for OSX either now or in short term plans.
You can use INDE Audio for MP3 decoding on Windows only.