Convert AAC to OGG (Vorbis) Online
Convert AAC files to OGG Vorbis, the open and patent-free audio format. Free, in your browser, no file uploads.
.aac, .m4a · up to 100 MB
What you can do
AAC to OGG: open audio for Linux, Android, and game engines
Linux and Android native
OGG Vorbis is a native format on Linux and Android since their earliest versions. No additional licenses.
100% private
Your audio files never leave your device. Local processing without servers.
Patent-free
Vorbis and the OGG container are completely royalty-free under Xiph.Org's BSD license.
Game engines
Unity, Godot, and GameMaker use OGG as a native format for music and sound effects.
How it works
Three steps, no hassle
Upload your AAC file
Drag or select your .aac (or .m4a with AAC audio) file. No signup or installs required.
Vorbis re-encoding in the browser
The AAC audio is decoded and re-encoded to Vorbis in the OGG container, entirely on your device via WebAssembly.
Download your OGG
OGG Vorbis file ready for Linux/Android players, game engines, or any platform that prefers open formats.
FAQ
Got questions?
Yes, there is additional loss. Both AAC and Vorbis are lossy codecs: the AAC already discarded information from the original audio during its first compression. Re-encoding to Vorbis produces a second generation of loss on top of the already-degraded audio, which can amplify artifacts like pre-echo, 'metallic' resonance, or smearing of transients. The magnitude of this additional loss depends on the target bitrate: at 192 kbps OGG, the difference from Apple Music's 256 kbps AAC is imperceptible for most listeners in a double-blind test; at 96 kbps, artifacts become more audible. Lossy-to-lossy conversion is always a degradation, though practically inaudible at high bitrates.
Both are second-generation codecs (post-MP3) with similar efficiency. AAC was published as an ISO standard in 1997; Vorbis was released by the Xiph.Org Foundation in July 2002. Subjective quality studies (listening tests) conducted by Hydrogenaudio and the EBU (European Broadcasting Union) in 2007 and 2010 showed that AAC-LC at 128 kbps and Vorbis q5 (~160 kbps) offer very similar subjective quality. At low bitrates (64–96 kbps), AAC-HE (High Efficiency AAC) outperforms Vorbis thanks to SBR (Spectral Band Replication). At medium-high bitrates (128–256 kbps), Vorbis is considered comparable or slightly superior in transparency for voices and acoustic instruments.
Linux: all major players (VLC, mpv, Rhythmbox, Amarok) support OGG Vorbis natively. Android: since Android 1.0 (2008), OGG Vorbis is a native audio format supported by the OS. Firefox and Chrome: both browsers decode OGG Vorbis without plugins since their early versions (Firefox 3.5 in 2009, Chrome 3 in 2009). Portable players: Rockbox (open firmware for portable players like iPod) supports OGG. Game engines: Unity, Godot, and GameMaker use OGG Vorbis as a native audio format for sound effects and music. Notable exceptions are iOS/Safari (without native support until recently) and conventional CD/DVD players.
The main reason is not quality but philosophy and ecosystem compatibility. OGG Vorbis is completely patent-free and its specification is public under the BSD license: Xiph.Org (the foundation behind Vorbis, FLAC, Opus, and Theora) was created with the explicit goal of providing royalty-free audio and video codecs. AAC has active patents managed by the Via Licensing pool (formerly MPEG LA) that require licenses for commercial implementations. For open-source projects, Linux distributions, indie game engines, and platforms that prefer to avoid legal restrictions, OGG is the natural choice. Additionally, Android and Firefox have native support for OGG Vorbis, simplifying audio distribution in cross-platform applications.
AAC in M4A containers uses iTunes tags (MP4 atoms: ©nam, ©ART, ©alb, ©day, gnre, trkn). OGG Vorbis uses Vorbis Comment, a system of key=value pairs in plain text (TITLE, ARTIST, ALBUM, DATE, GENRE, TRACKNUMBER). Conversion maps standard tags between both systems: title, artist, album, year, genre, and track number are correctly transferred by most converters. Cover artwork is stored in Vorbis Comment as base64-encoded METADATA_BLOCK_PICTURE blocks, and most modern converters transfer it from M4A. Proprietary iTunes tags like 'podcast', 'rating', or ratings have no direct equivalent in Vorbis Comment.
Yes, it is the de facto standard in the indie game development industry and open-source engines. Unity supports OGG Vorbis as one of its native audio formats and recommends it for background music due to its good quality-to-size ratio. Godot Engine uses OGG Vorbis as its primary audio format for streaming (long music and voices). GameMaker Studio 2 supports OGG for streaming audio. The advantage of OGG in games is the absence of distribution royalties (unlike MP3, which required licenses until 2017) and native support on all common target platforms (Windows, Linux, Android, Web/HTML5 via WebAudio API). For short sound effects, WAV or FLAC is preferred to avoid the startup latency of lossy decoding.
Convert AAC to OGG Vorbis: from the Apple ecosystem to open audio
The AAC (Advanced Audio Coding) codec was developed by Fraunhofer IIS, Dolby, Sony, and AT&T and published as ISO standard 13818-7 in 1997, designed as a successor to MP3 with better quality at the same bitrate thanks to a higher-resolution MDCT filter bank and a more sophisticated psychoacoustic model. Apple adopted AAC as iTunes' native codec in 2003 and made it the de facto standard for digital music distribution in the Apple ecosystem (iTunes Store, Apple Music, M4A podcasts). Despite its technical superiority over MP3, AAC is subject to patents managed by the Via Licensing consortium — formerly MPEG LA — that impose royalties for commercial implementations, which has created persistent friction in free software and open-source ecosystems. Vorbis, in contrast, was developed by the Xiph.Org Foundation — founded by Chris Montgomery, creator of the experimental Ogg Squish codec — and published in its stable version 1.0 in July 2002 with the explicit goal of offering a high-quality audio codec completely free of patents and royalties. Xiph.Org has produced a complete family of open codecs: FLAC (2001), Vorbis (2002), Speex (2003), Theora (2004), Opus (2012), and the experimental Daala. The OGG container is a multipurpose format capable of holding streams of any of these codecs, though the OGG Vorbis combination for audio is the most widely used. The complete Vorbis specification was published under the BSD license, enabling free implementation in any project without commercial license agreements. This makes OGG Vorbis the format of choice for open-source projects, Linux distributions, and any developer or organization that needs to distribute audio content without incurring licensing costs or legal uncertainty about patent coverage across jurisdictions.
The technical comparison between AAC and Vorbis is an ongoing subject of debate in the audiophile community and audio engineering literature. Both codecs use MDCT (Modified Discrete Cosine Transform) transforms as the foundation of their encoding process, and both apply psychoacoustic models to determine what information can be discarded without the listener noticing. The main difference lies in implementation details: AAC uses 1024- or 128-point MDCT windows with adaptive transitions (short window mode for transients), while Vorbis uses 2048- or 256-point windows with variable overlap. The most cited subjective quality studies are those of the Hydrogenaudio community (2007) and the EBU (European Broadcasting Union, Technology and Innovation Report 3335, 2010): both showed that AAC-LC at 128 kbps and Vorbis at quality q5 (approximately 160 kbps) offer comparable perceived quality in double-blind tests. At very low bitrates (below 96 kbps), AAC-HE gains an advantage thanks to SBR (Spectral Band Replication), which reconstructs high frequencies from the low-frequency data. In the context of AAC-to-OGG conversion, it is critical to remember that this is a lossy-to-lossy conversion: audio already degraded by AAC is degraded again passing through Vorbis, potentially amplifying artifacts like pre-echo or smearing of percussive transients. To minimize this additional degradation, using q6 or higher in Vorbis — equivalent to approximately 192 kbps — is recommended. Another strategy to reduce additional loss is to first decode the AAC to uncompressed WAV and then encode directly to Vorbis, avoiding any toolchain that might introduce additional rounding during the decoding stage, though in practice the measurable difference is imperceptible above q5 in a double-blind test with trained listeners.
The most relevant use case for AAC to OGG conversion in 2025 is the indie video game development ecosystem and Linux and Android platforms. Unity Technologies, in its updated official documentation, recommends OGG Vorbis as the preferred format for background music in game projects, for its native support across all Unity target platforms (Windows, macOS, Linux, Android, iOS, WebGL) and for the complete absence of distribution royalties. Godot Engine, the most popular open-source game engine according to the 2024 Stack Overflow developer survey, uses OGG Vorbis as its primary audio format for streaming music and long voice tracks, while reserving WAV or FLAC for short sound effects where decoding latency is critical for interactive response. For developers who obtain music under Creative Commons licenses or purchase audio packs in Apple formats (M4A/AAC), converting to OGG greatly simplifies integration in these cross-platform development environments. In the Linux ecosystem, OGG Vorbis is the audio format recommended by the Free Software Foundation and is included by default in all major distributions, including Ubuntu, Fedora, Arch Linux, and Debian. Firefox and Chrome implemented native support for OGG Vorbis in 2009 (Firefox 3.5 in June 2009, Chrome 3 in October 2009), enabling direct playback in the HTML5 <audio> element without additional plugins. Convertir.ai performs all conversion in the browser via WebAssembly, without servers or file uploads. The conversion runs entirely offline once the page has loaded, making it suitable for environments with restricted network access or for users who need to process sensitive audio files without sending them to third-party infrastructure.