Convert ALAC to WMA — Free Online Tool
Convert ALAC audio files (.m4a) to WMA format using the wmav2 codec, transcoding Apple's lossless audio into Microsoft's proprietary lossy format for compatibility with Windows Media Player and Windows-ecosystem devices. Because ALAC is lossless, this conversion will introduce compression artifacts for the first time — your source file is the best possible starting point for the output quality.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your ALAC file here
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Free — no uploads, no signups. Your files never leave your browser.
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 inside an MPEG-4 container, meaning every sample from the original recording is preserved exactly. During this conversion, FFmpeg decodes the ALAC stream to raw PCM, then re-encodes it using the wmav2 codec (Windows Media Audio v2) at a target bitrate of 128 kbps, writing the result into a .wma container. This is a full transcode — not a remux — because the source and destination codecs are completely different. The wmav2 encoder applies lossy perceptual compression, discarding audio information the algorithm judges to be inaudible, so the resulting WMA file will be smaller than the ALAC source but will not be bit-for-bit identical to the original recording.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg application, the open-source multimedia processing engine that powers this conversion both in the browser (via FFmpeg.wasm) and on the desktop command line. |
-i input.m4a
|
Specifies the input file — an ALAC audio file stored in an MPEG-4 container with the .m4a extension. FFmpeg detects the 'alac' audio stream inside the container and decodes it to raw PCM for re-encoding. |
-c:a wmav2
|
Sets the audio codec for the output to wmav2 (Windows Media Audio v2), Microsoft's improved proprietary lossy audio codec and the standard encoder for producing WMA files compatible with modern Windows software and devices. |
-b:a 128k
|
Targets an audio bitrate of 128 kilobits per second for the wmav2 encoder. This controls the trade-off between file size and audio quality; since the ALAC source is lossless, this is the primary quality-defining parameter for the output WMA file. |
output.wma
|
Defines the output filename and triggers FFmpeg to write the encoded wmav2 audio stream into a WMA/ASF container, the standard file format for Windows Media Audio content. |
Common Use Cases
- Sharing music purchases ripped from Apple Music or iTunes with colleagues or family members who use Windows Media Player, which does not support ALAC natively
- Loading your Apple lossless music library onto older Windows-based portable media players or car stereos that only accept WMA or MP3 files
- Preparing audio content for distribution through a Windows-centric corporate intranet or e-learning platform that encodes or streams in WMA format
- Archiving a converted copy of an ALAC recording in WMA for compatibility with legacy Windows XP or Windows 7 systems that lack codec packs for ALAC playback
- Creating smaller WMA versions of large ALAC audiobook or podcast files produced in Apple's ecosystem for playback on Windows-based digital audio devices with limited storage
Frequently Asked Questions
Yes — this is an unavoidable one-way quality tradeoff. ALAC is lossless, meaning it perfectly preserves every audio sample from the original source. WMA (wmav2) is a lossy codec, so the encoder discards audio data it considers perceptually irrelevant during compression. At the default 128 kbps bitrate, most listeners will not notice a significant difference on typical consumer headphones, but the conversion is irreversible: you cannot recover the original lossless quality from the WMA file. Always keep your original ALAC file if audio fidelity matters.
ALAC encodes audio losslessly, which means file sizes are typically 40–60% of uncompressed WAV/PCM but still very large compared to lossy formats. WMA at 128 kbps uses aggressive perceptual compression to target a fixed bitrate, so a 40 MB ALAC file might compress down to 5–8 MB in WMA. The dramatic size reduction comes entirely from the lossy compression discarding audio data, not from a smarter lossless algorithm.
FFmpeg will attempt to map common metadata tags from the MPEG-4 container (where ALAC is stored) to the WMA container's ASF tag format. Standard fields like title, artist, album, and year are generally preserved. However, ALAC files from iTunes may contain Apple-specific tags (like iTunes artwork stored in a non-standard atom) that do not have direct equivalents in the WMA/ASF format and may be silently dropped during conversion. It is worth verifying tags in your WMA file after conversion using a tag editor.
Yes. Replace '128k' in the '-b:a 128k' flag with a higher value such as '192k', '256k', or '320k' to give the wmav2 encoder more data to work with, resulting in better audio fidelity and a larger file. For example: 'ffmpeg -i input.m4a -c:a wmav2 -b:a 192k output.wma'. Since your source is lossless ALAC, increasing the bitrate is worthwhile if compatibility with your target device allows it — you are only limited by what the destination player or platform supports.
The single-file command shown here processes one file at a time, but you can run it in a loop from the command line on your desktop. On Linux or macOS: 'for f in *.m4a; do ffmpeg -i "$f" -c:a wmav2 -b:a 128k "${f%.m4a}.wma"; done'. On Windows Command Prompt: 'for %f in (*.m4a) do ffmpeg -i "%f" -c:a wmav2 -b:a 128k "%~nf.wma"'. The browser tool processes files individually, so batch conversion is best handled locally using the FFmpeg command directly.
In nearly all cases, wmav2 is the better choice and is what this tool uses by default. WMA v2 is an improved version of the codec that offers better audio quality at the same bitrate compared to the older wmav1, and it is supported by virtually every device or application that plays WMA files. WMA v1 (wmav1) is only relevant if you need to target extremely old hardware or software from the late 1990s that specifically cannot decode v2 streams. You can switch to it by replacing 'wmav2' with 'wmav1' in the FFmpeg command, but there is rarely a practical reason to do so.
Technical Notes
ALAC files are stored in the MPEG-4 container with the .m4a extension, sharing the same container as AAC audio — the difference is purely in the codec inside. When FFmpeg reads the input, it identifies the 'alac' audio stream and fully decodes it to uncompressed PCM before passing it to the wmav2 encoder. The WMA container is based on Microsoft's Advanced Systems Format (ASF), which has no support for lossless audio or chapter markers — both of which ALAC can carry. Any chapter data embedded in your ALAC file will be silently lost during conversion because the WMA/ASF format does not support that feature. The wmav2 codec uses a lossy transform-based compression scheme and targets the specified bitrate using variable quantization; the default 128 kbps is a reasonable middle ground for speech and general music, but audiophile recordings from high-resolution ALAC sources (24-bit/96kHz, for example) will see a more noticeable quality reduction at this bitrate than standard CD-quality 16-bit/44.1kHz sources. WMA does not support multi-channel audio beyond stereo in most standard wmav2 configurations — if your ALAC source is a multi-channel surround file, the downmix behavior should be confirmed before conversion.