Idolm@ster 2 voice bnsf files by min at 7:49 AM EST on December 18, 2016
I've been trying to extract the voice audio files form this game but with no luck (BGM converts fine). There is a 2 at 0x14 in the header which should typically be a 0. Changing this to 0 and then converting it in vgmstream gives scrambled audio. I would appreciate any help on these files.
It might possibly be encryption since a lot of the games files are encrypted, I was surprised to see the nub2 files weren't. I will take a look in the ps3's ram with the game running and see if anything gets decrypted.
Bizarrely enough, I also just started looking into this just this night. I believe it's just a slight modification or set of settings to the Siren codec, since we are getting some valid samples out of it. We're hitting the "frame error" case in Siren causing it to blank out samples. When I get a bit more spare time I can look into which frame error we're hitting.
Apparently bxaimc was looking into this back in 2011, but I assume didn't make any progress.
Have been comparing the bitstream we have with the specification at: http://www.itu.int/rec/T-REC-G.722.1-200505-I/en
The current libsiren we use has problems decoding some frames that Polycom's decoder doesn't, and also has various modes currently hardcoded. I was hoping check it later but it'd be great if you can take a look. https://github.com/kode54/libg7221_decode/
From the extra samples min provided you can see clean patterns, probably no encryption. I tried a few tricks (big/little endian swap, xor frame header, etc) but nothing. Polycom's decoder can't decode it either: http://docs.polycom.com/global/downloads/company/about_us/technology/siren14_g7221c/Siren14PCExecutable.zip
Here is a variation of Polycom's implementation maybe we could use to compare: https://github.com/traviscross/freeswitch/tree/master/libs/libg722_1