Convert WMV to ALAC — Free Online Tool
Convert WMV files to ALAC (Apple Lossless Audio Codec), extracting the audio track from Microsoft's proprietary video container and re-encoding it into a lossless .m4a file fully compatible with iTunes, Apple Music, and the broader Apple ecosystem. Because WMV audio is typically encoded with the lossy WMA v2 codec, ALAC preserves the decoded audio at its maximum recoverable quality with no further generation loss.
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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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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
WMV files store video and audio in Microsoft's Advanced Systems Format (ASF) container. During this conversion, FFmpeg demuxes the ASF container to extract the audio stream — typically encoded in WMA v2 (wmav2) — decodes it to raw PCM audio, and then re-encodes it using the ALAC codec into an MPEG-4 (.m4a) container. Because WMA is a lossy format, the source audio has already sustained compression artifacts from its original encoding; ALAC captures the decoded result perfectly and introduces no additional quality loss. The video stream is discarded entirely, since ALAC is a pure audio format. The resulting .m4a file will be larger than the original WMA audio stream but is bit-for-bit stable — re-encoding it again from ALAC will always produce the same decoded audio.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool — in this browser-based tool, it runs as FFmpeg.wasm compiled to WebAssembly, executing entirely within your browser with no server upload. When running locally, this calls your desktop FFmpeg installation. |
-i input.wmv
|
Specifies the input file — a WMV file stored in Microsoft's ASF container, which FFmpeg will demux to extract the WMA v2 audio stream (and the video stream, which will be discarded since ALAC is audio-only). |
-c:a alac
|
Instructs FFmpeg to encode the audio stream using Apple's ALAC (Apple Lossless Audio Codec) encoder. The decoded WMA audio is re-encoded losslessly into ALAC, capturing the full fidelity of the decoded audio with no further compression artifacts. |
-c:a alac
|
A duplicate of the preceding audio codec flag — this redundancy has no effect since FFmpeg honors the final applicable codec instruction, which is identical. In a manually crafted command, only one instance of `-c:a alac` is needed. |
output.m4a
|
Defines the output filename with the .m4a extension, which signals FFmpeg to wrap the ALAC audio in an MPEG-4 container — the standard packaging used by Apple Music, iTunes, and iOS devices for ALAC lossless audio files. |
Common Use Cases
- Importing archived WMV recordings — such as old corporate training videos or conference captures — into Apple Music or iTunes as permanent lossless audio archives
- Extracting commentary or narration from WMV screencasts or lecture recordings to preserve the audio at the highest possible quality for editing in Logic Pro or GarageBand
- Migrating a Windows Media Player music video library to an Apple-centric workflow where ALAC is the preferred lossless format for iPhone and iPad sync
- Pulling audio from WMV episodes of older web series or podcasts originally distributed in Windows Media format, converting them for playback on Apple devices without transcoding loss
- Archiving the audio portion of WMV DV camcorder exports from the early 2000s into a future-proof lossless container before the original files degrade or become unplayable
Frequently Asked Questions
No — ALAC is lossless, but it can only preserve what is already in the source file. WMV audio encoded with WMA v2 is a lossy codec, meaning some audio detail was permanently discarded when the WMV was originally created. What ALAC guarantees is that no additional quality loss occurs during this conversion: the decoded WMA audio is captured exactly and stored losslessly. Think of it as the audio equivalent of making a perfect photocopy of an already-compressed image.
Two factors explain this. First, the WMV's WMA audio was heavily compressed with a lossy algorithm designed to reduce file size at the cost of some fidelity; ALAC uses lossless compression, which is far less aggressive. Second, the original WMV file included a video stream that is discarded during conversion — but the audio portion alone, stored losslessly, is typically larger than the compressed WMA audio stream in the original. A WMV with 128k WMA audio might yield an ALAC file several times larger in audio-only form.
Yes. ALAC stored in an MPEG-4 (.m4a) container is natively supported by iTunes, Apple Music, and all modern iOS and macOS devices. You can import the output file directly into your iTunes or Apple Music library and sync it to iPhone or iPad without any additional conversion. Apple introduced native ALAC support in iTunes 4.5 and has maintained it across every subsequent version.
FFmpeg will attempt to map compatible metadata from the ASF container's attribute fields to the MPEG-4 container's metadata atoms. Common tags such as title, author, and album often transfer correctly. However, ASF uses Microsoft-specific metadata structures that do not map perfectly to all MPEG-4 tag fields, so some custom or extended WMV metadata may be dropped or incorrectly mapped. It is worth verifying tags in iTunes or a tag editor like MusicBrainz Picard after conversion.
Yes. On Linux or macOS, you can run a shell loop: `for f in *.wmv; do ffmpeg -i "$f" -c:a alac "${f%.wmv}.m4a"; done`. On Windows Command Prompt, use: `for %f in (*.wmv) do ffmpeg -i "%f" -c:a alac "%~nf.m4a"`. This applies the same conversion logic to every WMV file in the current directory, outputting a matching .m4a for each. For files over 1GB, running FFmpeg locally like this is the recommended approach since the browser tool supports files up to 1GB.
This is a minor redundancy in the resolved command — both flags specify the same instruction to use the ALAC encoder for the audio stream. FFmpeg processes the last applicable instance of a codec flag, so the conversion behaves correctly and produces valid ALAC output. If you are running this command locally, you can safely use a single `-c:a alac` flag: `ffmpeg -i input.wmv -c:a alac output.m4a`. The result will be identical.
Technical Notes
WMV files use Microsoft's ASF (Advanced Systems Format) container, and their audio is almost universally encoded with WMA v2 (wmav2), a proprietary lossy codec. Converting to ALAC involves a full decode-reencode cycle: FFmpeg decodes the WMA bitstream to raw PCM and then losslessly compresses it with Apple's ALAC encoder. Because ALAC targets lossless compression of PCM, the bit depth and sample rate of the source audio are preserved exactly — typically 16-bit/44.1kHz for music-oriented WMV content. There are no audio quality settings to configure for ALAC since, by definition, lossless compression has no quality parameter. One notable limitation: WMV files that use Microsoft's DRM (PlayReady or older Windows Media DRM) will be unreadable by FFmpeg and cannot be converted — DRM-protected WMV files must first be authorized and decrypted through a licensed player. Additionally, WMV's ASF container supports multiple audio tracks, but ALAC in an MPEG-4 container supports only a single audio track; FFmpeg will default to the first (or best) audio stream. Chapter data is not present in WMV/ASF and will not be transferred, though ALAC's .m4a container does support chapters if you wish to add them post-conversion.