I've downloaded PVRTC_REL_2.firstname.lastname@example.org and used Linux_x86_32 version of libPVRTC.a library.
It appeared that pvrtc_decompress function produces RGBA image, which is strange, because the description in pvrtc.h states it should produce ARGB data. It also sorts ill with the pvrtc_compress function, which consumes ARGB data (not RGBA) and works well.
Whilst internally the compress function actually uses RGBA, I believe in the past it used ARGB and when we changed it we had various users requesting we continue using ARGB, so we changed it back. There’s never been such a request on the decompressor however, hence the disparity.
Unfortunately this is likely to remain the case now as we’re deprecating this library and will only provide bug fixes for the next release.