It's an Actions Semiconductor SoC. I'd be pretty surprised if it's not an ATJ2127 (or one of its familial siblings) -- ie <512KB RAM and HW codecs.
How much RAM does Rockbox normally need? Could something be removed (for example, games, tag-based browsing, etc) to reduce the memory requirement?
There seem to be plenty of cheap mp3 players on the market, all with pretty poor firmware, it'd be great if at least some of them supported Rockbox.