MOGG File Format

MOGG files are often used in Harmonix games for all platforms except for PS2 and DS. They are an extension of the OGG Vorbis container with an extra header prepending it, and almost all official MOGGs starting with Rock Band shipped on-disk and as DLC are encrypted.

The version value in the MOGG header is used to indicate which encryption key and format should be used for decryption.

Structure

MOGG Header

Name	Type	Size	Function
Version	Integer (LE)	4 bytes	Version of the MOGG file. Related to encryption (10 / 0xA = unencrypted)
Header Size	Integer (LE)	4 bytes	Length of the MOGG header / offset in the file where the OGG begins.
Map Version	Integer (LE)	4 bytes	Version of the MOGG map. (usually 16 / 0x10)
Buffer Size	Integer (LE)	4 bytes	Usually 20000 / 0x4E20. (TODO: what purpose?)
Entry Count	Integer (LE)	4 bytes	The number of entries in the MOGG header.
Entries	#MOGG Entry Array	sizeof(MOGG Entry) * Entry Count	Presumably a table to help the game stream the OGG file from disk.
AES Key	Byte Array	16 bytes	An AES key used to encrypt the file. Only present if MOGG version is >= 11 / 0xB.

MOGG Entry

TODO: is this correct?

Entry	Type	Size	Function
Byte Offset	Integer (LE)	4 bytes	Offset into the file that the entry starts.
Sample	Integer (LE)	4 bytes	The sample in the OGG stream that corresponds to the byte offset.

OGG File

Past this point is a regular OGG Vorbis format file containing multiple tracks. The tracks corresponding to instruments are defined in the songs.dta file.

Encryption

Generation	Info	Games
10 / 0xA	Unencrypted. Lacks key in MOGG header.	Used in Guitar Hero 2
11 / 0xB	128-bit AES EBC encryption with a static key. Uses key in MOGG header as IV.	Used in Rock Band on-disc songs

Tools

Several tools are available for working with MOGG files (creation/extraction, encryption, etc)

• Onyx Music Game Toolkit
• Magma
• ArkTool
• C3 CON Tools
• Audacity (supports reading smaller unencrypted MOGG files directly)

References

• xorloser's ScoreHero post
• Onyx Source Code