Does Android 1.5 Cupcake support WMA decoder? I pushed some WMA files to emulator yesterday, and I found all of these music files can be played well by the music player, So I was confused. 

I found that Android 1.5 didn't support the WMA codec, which is announced in the SDK 
documentation. I also didn't find a WMA decoder in PV OMX. 

How does this happen?
There isn't just one thing called WMA, WMA describes a whole set of different audio formats and technologies that all normally have a .WMA ending. Some of these are DRM encrypted, some have higher or lower level quality than others, some are optimized for voices. It's entirely possible that although your audio file has a .WMA extension and container, inside that it's actually a type of codec that Android can already natively handle.

See these links for a bit more explanation: Gentle Introduction to Video Encoding: Lossy Audio Codecs and Wikipedia - WMA