I see, Ive myself got a rk2706 player. This .img file you linked to in your post is a FAT image, if you mount it you should see something like this:
Code:
/:
appdata resource rk27boot.bin rk28img.chk system system00 version.bin
/appdata:
pytable.bin
/resource:
bid font language sid
/resource/bid:
bmp0.bin
/resource/font:
ft12.bin ft16.bin ft24.bin ft32.bin
/resource/language:
chinese codepage english
/resource/language/chinese:
gbk2u.bin ouft12.bin ouft16.bin ouft24.bin ouft32.bin ouft36.bin u2gb.bin
/resource/language/codepage:
cp1250.bin cp1253.bin cp1256.bin cp863.bin cp932.bin cp950.bin
cp1251.bin cp1254.bin cp1257.bin cp865.bin cp936.bin
cp1252.bin cp1255.bin cp437.bin cp874.bin cp949.bin
/language/english:
cwidth12.bin cwidth24.bin ouft12.bin ouft24.bin ouft36.bin
cwidth16.bin cwidth32.bin ouft16.bin ouft32.bin
/resource/sid:
stringid.bin
/system:
base.rkw jpgenc.bfw rk_h263.bin rk_mpeg2.out rock_flv.bin zzzz.rkz
div3_tab.bin realobj.bin rk_mjpg.out rk_mpeg4.out save.bin
dvenc.bfw register.dat rk_mp4v.bin rk_wmv2.bin wmv2_tab.bin
jpg.bfw rk_divx3.out rk_mpeg0.out rk_wmv3.bin wmv3_tab.bin
/system00:
base.rkw realobj.bin rk_mjpg.out rk_wmv2.bin wmv3_tab.bin
div3_tab.bin regcmm.dat rk_mp4v.bin rk_wmv3.bin zzzz.rkz
dvenc.bfw register.dat rk_mpeg0.out rock_flv.bin
jpg.bfw rk_divx3.out rk_mpeg2.out Save.bin
jpgenc.bfw rk_h263.bin rk_mpeg4.out wmv2_tab.bin
where "system/base.rkw" is the firmware. I've heard somewhere that this "new-style" firmware cannot be modded but I haven't tried this myself.
Also somebody mentioned to me that the free version of IDA doesn't contain ARM support (rk2706 main processor is an ARM, the DSP is a zsp500) but the demo version should work (
Hex-Rays IDA Page : Interactive Disassembler download page). To load the base.rkw into ida, open the file, choose ARM as the processor type
and 0x5fffffd4" as the loading address.
then goto address 0x60000000 and hit "c". For further info you may read this: "http://alemaxx.al.funpic.de./rk27/rkwfwpatch.html
Good luck