What is the MOGG file format?
Files with the .mogg extension store compressed audio data in binary notation. They are referred to as a container-style format since they carry multiple separate instrument stems - drums, bass, guitar, vocals and more - multiplexed into a single Ogg Vorbis bitstream. The .mogg format was developed by Harmonix Music Systems and is used primarily in music rhythm games such as Rock Band and Guitar Hero.
Thanks to .mogg files, a rhythm game engine can mute or solo each stem in real time during gameplay. A song file most often contains tracks for:
- vocals,
- guitars,
- drums,
- bass,
- synthesizers.
Some channels may appear duplicated - in reality they are mono recordings for the left and right stereo sides, which together create spatial sound. Files are often sourced from original multitrack tape recordings, where each instrument is separated on a dedicated workstation before being mixed down to a single .mogg file.
Plain .mogg files begin with the standard OggS signature at byte offset 0, identical to a regular .ogg file. Many retail Rock Band and Guitar Hero releases, however, prefix the stream with an encrypted header - a 4-byte Harmonix version word, commonly 0x0A or 0x0B and higher - that must be stripped or decrypted before the audio becomes playable. Tools such as Onyx Music Game Toolkit handle this step automatically.
Upon opening a .mogg file in audio creation and editing software, such as Audacity or Avid Pro Tools, there is also the option to save it in another format. This allows conversion to more widely supported formats, for example .MP3, .FLAC, .WAV or .wma. It is possible to export all stems or only a selected subset using the export function for a selected audio track or the entire file.
Security & safety
RISK: LOWMOGG is plain game audio data with no executable code, so the file itself is low risk. The practical caution is legal/copyright: ripped retail MOGGs contain licensed master recordings. Third-party "demogg" utilities should be obtained from the known custom-songs community projects (Onyx, Magma) rather than random sites.
Format details
in a nutshell- Generic Ogg variants mislabeled .mogg - Occasional non-Harmonix multitrack Ogg exports reuse the extension but follow the same Ogg Vorbis structure.
Programs that open MOGG files
Windows3 apps
Audacity
Open-source First decrypt if needed, rename .mogg → .ogg, then File → Import → Audio; each stem loads as a track. 
VLC media player
Open-source Rename a plain/decrypted MOGG to .ogg and open it; plays the multichannel mix. 
Onyx Music Game Toolkit
Open-source Use to decrypt/encrypt and inspect Rock Band MOGGs and split stems. 
macOS1 app
Linux1 app
Technical details
deep spec| Container format | Ogg (Xiph) bitstream - identical page structure to a standard `.ogg` file |
| Audio codec | Vorbis (lossy compression) |
| Encoding | Binary, little-endian byte order |
| Channel structure | Multiple interleaved mono stems (drums, bass, guitar, vocals, keys, etc.) multiplexed into one Ogg stream, allowing a game engine to mute or solo each stem at runtime |
| Typical sample rate | 44.1 kHz |
| Source bit depth | 16-bit |
| Typical file size | 10 MB - 60 MB per song (varies with stem count and track duration) |
| Magic bytes | `OggS` (hex: `4F 67 67 53`) at offset 0 for plain files; encrypted retail MOGGs prefix the stream with a Harmonix header, pushing `OggS` to a non-zero offset |
| Integrity checking | Per-page CRC32 checksum inherent to the Ogg container specification |
| Encryption | None in plain or community-created files; official Rock Band / Guitar Hero titles use a Harmonix obfuscation header (version words `0x0A`-`0x10`) |
| MIME type | `audio/ogg` (also served as `application/octet-stream` in some contexts) |
| Platform support | Windows, macOS, Linux, Xbox 360, PlayStation 3, Wii |
| Developer | Harmonix Music Systems (built on the open Xiph Ogg Vorbis standard) |
| Stem mapping | Channel-to-instrument assignments are stored in an external `.mid` or song-metadata file, not inside the `.mogg` itself |
| Decryption output | Stripping the Harmonix header yields a standard multichannel `.ogg` playable in any Ogg-compatible player |
| Released | 2007 (Rock Band, Harmonix); built on Xiph Ogg Vorbis (1.0, 2002) |
| Latest version | Ogg Vorbis I; encrypted variants in later Rock Band / Guitar Hero titles |
| Open standard | Yes · royalty-free |
| Specification | xiph.org |
MOGG conversions
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