Update: Updated once more today, ArkTool with Source Code and GUI v6.1 for PS3 is available which now includes additional fixes and Linux support.
Recently xorloser released ArkTool with Source Code and GUI v5.2 for PS3 which can edit ARK/HDR files found in games including Guitar Hero 1, Guitar Hero 2, Guitar Hero 80s, Rockband, and Karaoke Revolution.
Today, he has updated it to ArkTool with Source Code and GUI v6.0 for PS3!
To quote from his page- v6.0 changes:
* now decrypts rockband song files on the fly when extracting them from ARK files
I've said it before, but these tools and source code will work with the following games for any system including PS2, PS3, X-Box, X-Box 360.
Games: Guitar Hero 1, Guitar Hero 2, Guitar Hero 80s, Rockband, Karaoke Revolution. (Sorry but Guitar Hero 3 uses a different format to all the above)
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