Convert ALAC to OGA — Free Online Tool
Convert ALAC audio files (.m4a) to OGA format using Vorbis encoding directly in your browser. This tool transcodes Apple's lossless audio into an open, streaming-friendly Ogg Vorbis stream — ideal for replacing proprietary Apple audio with a royalty-free alternative compatible with Linux media players and web applications.
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FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
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Settings
Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
ALAC stores audio as lossless PCM data compressed inside an MPEG-4 container. During this conversion, FFmpeg fully decodes the ALAC stream back to raw PCM, then re-encodes it using the libvorbis encoder into a Vorbis audio stream, which is wrapped in an Ogg container and saved as an .oga file. Because ALAC is lossless, the decoded PCM represents the original audio perfectly — the only quality loss introduced is from the Vorbis encoding step itself. At the default quality setting of -q:a 4 (roughly 128–160 kbps variable bitrate), the output is perceptually transparent for most listeners. The Ogg container supports chapter markers, which are preserved from the ALAC source if present.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg binary — the open-source multimedia processing engine that handles decoding the ALAC stream from the MPEG-4 container and re-encoding it as Vorbis inside an Ogg container. |
-i input.m4a
|
Specifies the input file — an .m4a file containing an ALAC (Apple Lossless) audio stream. FFmpeg reads the MPEG-4 container and identifies the ALAC codec internally, regardless of the .m4a extension. |
-c:a libvorbis
|
Selects the libvorbis encoder to produce Vorbis audio in the output — the open, royalty-free lossy codec that is the standard audio stream type for OGA files. This replaces the lossless ALAC codec from the source. |
-q:a 4
|
Sets the Vorbis variable bitrate quality level to 4 on a 0–10 scale, targeting approximately 128–160 kbps. This is a balanced default that provides good perceptual quality from the decoded lossless ALAC source without unnecessarily large file sizes. |
output.oga
|
Defines the output filename and tells FFmpeg to write an Ogg container (.oga extension), which wraps the encoded Vorbis audio stream in the open Ogg format used by Linux media players and web audio APIs. |
Common Use Cases
- Moving an iTunes or Apple Music library to a Linux desktop where ALAC playback support is limited but Ogg Vorbis is natively supported by players like Rhythmbox or Amarok
- Preparing lossless Apple audio recordings for upload to open-source platforms or self-hosted music streaming servers such as Navidrome or Subsonic that prefer open formats
- Reducing the file size of large ALAC audiobook or podcast recordings before distributing them, since Vorbis OGA files are significantly smaller than lossless ALAC sources
- Converting ALAC instrument samples or field recordings into OGA for use in open-source game engines like Godot, which natively support Ogg Vorbis audio assets
- Stripping Apple ecosystem dependency from audio files in archival workflows where long-term format openness and royalty freedom are a requirement
- Preparing audio tracks from ALAC music collections for embedding in web applications using the HTML5 audio element, where OGA/Vorbis has broad support in Firefox and Chrome
Frequently Asked Questions
Yes, there is a quality trade-off: ALAC is lossless, so the conversion to Vorbis (a lossy codec) introduces some degree of irreversible compression. At the default quality setting of -q:a 4, Vorbis targets roughly 128–160 kbps variable bitrate, which is considered perceptually transparent by most listeners on typical audio content. However, if you are archiving master recordings, you may want to either use a higher -q:a value (up to 10) or choose FLAC inside the OGA container instead to stay lossless.
Yes. The OGA container supports FLAC audio streams in addition to Vorbis and Opus. To do this, change the FFmpeg command to use '-c:a flac' instead of '-c:a libvorbis' and remove the '-q:a 4' flag, since FLAC does not use a quality scale. The resulting .oga file will contain a lossless FLAC stream, preserving every bit of the original ALAC audio. This is the best option if you need to retain the original audio fidelity while switching away from the Apple-proprietary container.
ALAC audio is stored inside an MPEG-4 container, which uses the .m4a file extension — the same container Apple uses for AAC audio. The difference is in the audio codec inside: .m4a files can contain either AAC (lossy) or ALAC (lossless). FFmpeg identifies the actual codec from the file's internal metadata rather than the extension, so it correctly decodes ALAC regardless of the .m4a extension.
ALAC in an MPEG-4 container supports chapter metadata, and the Ogg container also supports chapters. However, chapter format compatibility between the two containers is not guaranteed during this conversion — FFmpeg may not automatically translate MPEG-4 chapter atoms into Ogg chapter markers. If chapters are critical, verify the output in a player like VLC after conversion and consider using tools like 'ffprobe' to inspect the output metadata.
The '-q:a 4' flag controls Vorbis quality on a scale from 0 (lowest, ~64 kbps) to 10 (highest, ~500 kbps). To increase quality, raise the value — for example, '-q:a 6' targets approximately 192 kbps and '-q:a 8' targets approximately 256 kbps. Since you are starting from a lossless ALAC source, increasing the quality setting will produce output closer to the original, at the cost of a larger file size.
On Linux or macOS, you can loop over all .m4a files in a directory with: 'for f in *.m4a; do ffmpeg -i "$f" -c:a libvorbis -q:a 4 "${f%.m4a}.oga"; done'. On Windows PowerShell, use: 'Get-ChildItem *.m4a | ForEach-Object { ffmpeg -i $_.FullName -c:a libvorbis -q:a 4 ($_.BaseName + ".oga") }'. This processes each file sequentially, applying the same Vorbis quality setting to all conversions.
Technical Notes
ALAC is a bit-perfect lossless codec proprietary to Apple, stored in the MPEG-4 (.m4a) container. Because the source is lossless, FFmpeg decodes it to raw PCM with zero degradation before passing it to the libvorbis encoder. Vorbis is a psychoacoustic lossy codec — it discards audio information deemed imperceptible to human hearing — so the conversion is a one-way lossy process; you cannot recover the original lossless data from the OGA output. The -q:a variable bitrate scale is specific to Vorbis and does not map directly to a fixed bitrate, so actual file sizes vary depending on audio complexity. Standard ID3-style metadata tags (artist, album, title, track number) embedded in the ALAC source should be carried over into Ogg comment tags by FFmpeg during conversion. However, embedded album artwork in MPEG-4 containers is not supported in OGA and will be dropped. The Ogg container is an open, patent-free format with no royalties, making OGA/Vorbis files legally straightforward to distribute and supported natively in Firefox, Chrome, most Linux audio stacks, and open-source media players.