Extract Audio from MP4 to WMA — Free Online Tool
Extract and convert audio from MP4 video files into WMA format using Microsoft's wmav2 codec — all processed locally in your browser with no uploads required. WMA is ideal for Windows Media Player compatibility, legacy Windows workflows, and streaming scenarios where Microsoft's audio ecosystem is preferred.
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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
This conversion strips the video stream entirely from the MP4 container and re-encodes the audio into Windows Media Audio format. Because MP4 typically carries AAC or MP3 audio while WMA uses Microsoft's proprietary wmav2 codec, a full audio transcode is required — the audio is decoded from its source codec and re-encoded into wmav2 at the target bitrate (default 128k). No video data is passed through; only the first audio track from the MP4 is extracted and encoded. This means every conversion involves a lossy transcode step, and any secondary audio tracks, subtitle tracks, or chapter markers present in the MP4 will be discarded, as WMA does not support those features.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg program, the open-source multimedia processing engine that powers this conversion both in the browser (via FFmpeg.wasm) and on the desktop. |
-i input.mp4
|
Specifies the input file — in this case an MP4 container, which may hold video (typically H.264), audio (typically AAC), subtitles, and chapters that FFmpeg will parse and make available for processing. |
-vn
|
Disables video output entirely, telling FFmpeg to ignore the video stream from the MP4. Since WMA is an audio-only format, this flag ensures no attempt is made to include video data in the output. |
-c:a wmav2
|
Sets the audio encoder to wmav2, Microsoft's second-generation Windows Media Audio codec. This triggers a full re-encode of the MP4's audio (typically AAC) into the WMA proprietary format, which is required since the source and destination codecs are incompatible. |
-b:a 128k
|
Sets the audio bitrate to 128 kilobits per second, the default quality setting for this conversion. This is a reasonable balance between file size and audio fidelity for speech and general music; increase to 192k or 320k for higher quality output. |
output.wma
|
Defines the output filename and triggers FFmpeg to wrap the encoded wmav2 audio stream in a WMA container — Microsoft's proprietary format that supports streaming, metadata tags, and optional DRM, though no DRM is applied here. |
Common Use Cases
- Preparing audio content for playback in Windows Media Player or legacy Windows-based media systems that expect WMA files natively
- Converting MP4 recordings or lectures into WMA for distribution on platforms or intranet systems built around Microsoft's media infrastructure
- Extracting the audio from an MP4 interview or podcast recording and delivering it as a WMA file to a client or broadcaster with a Windows-only workflow
- Archiving MP4 video audio tracks as standalone WMA files for use in Windows-centric digital asset management systems
- Stripping audio from MP4 marketing or training videos to produce WMA files compatible with older Microsoft SharePoint or Windows Media Services streaming setups
- Extracting background music or narration from an MP4 project file to use in a Windows-native audio editing tool that imports WMA directly
Frequently Asked Questions
Yes, some quality loss is inevitable. The audio in your MP4 is almost certainly already lossy (typically AAC or MP3), and transcoding it into wmav2 introduces a second generation of lossy compression. At the default 128k bitrate, the result is generally acceptable for speech and casual listening, but audiophiles or professionals working with music should use the highest available bitrate (320k) to minimize degradation. There is no lossless WMA option in this tool, as WMA Lossless requires a different codec not broadly supported by FFmpeg's wmav2 encoder.
FFmpeg will attempt to carry over common metadata tags — such as title, artist, and album — from the MP4 container into the WMA file, as WMA does support standard metadata tags. However, MP4-specific metadata structures (like iTunes-style atoms or embedded cover art in certain formats) may not transfer completely or correctly. If precise metadata preservation matters, you should verify the output tags in a tool like MediaInfo or Windows Media Player after conversion.
WMA is a single-stream audio-only format and does not support multiple audio tracks, subtitle tracks, or chapter markers. This conversion extracts only the first audio stream from the MP4 and discards everything else — including secondary language tracks, commentary tracks, and any embedded subtitles. If you need a specific audio track other than the first one, you would need to modify the FFmpeg command to select it using the '-map' flag.
Replace the '-b:a 128k' value with your desired bitrate. WMA (wmav2) supports bitrates of 64k, 96k, 128k, 160k, 192k, 256k, and 320k. For example, to get higher quality audio, use '-b:a 192k' or '-b:a 320k' in place of '-b:a 128k'. Lower bitrates like 64k are suitable for voice recordings where file size is a priority, while 192k or above is recommended for music.
The displayed command processes a single file, but you can batch convert on your desktop using a shell loop. On Linux or macOS, run: for f in *.mp4; do ffmpeg -i "$f" -vn -c:a wmav2 -b:a 128k "${f%.mp4}.wma"; done. On Windows Command Prompt, use: for %f in (*.mp4) do ffmpeg -i "%f" -vn -c:a wmav2 -b:a 128k "%~nf.wma". The browser-based tool processes one file at a time.
For virtually all use cases, wmav2 is the correct choice. It is the second-generation Windows Media Audio codec, offering better compression efficiency and audio quality than wmav1 at equivalent bitrates. wmav1 is only relevant for compatibility with very old or embedded devices that predate WMA version 2 support — hardware from roughly the early 2000s. If your target playback environment is Windows Media Player, any modern Windows application, or a current media player with WMA support, wmav2 will work without issue.
Technical Notes
The wmav2 codec used in this conversion is FFmpeg's implementation of Microsoft's Windows Media Audio v2 standard. WMA is a proprietary, lossy-only format (in this context), which means every MP4-to-WMA transcode involves decoding the source audio — typically AAC at 128k in standard MP4 files — and re-encoding it using Microsoft's algorithm. This double-lossy process is an inherent limitation of the format pair. The WMA container does not support video streams, chapter data, subtitle tracks, or multiple audio streams, so those elements from the source MP4 are permanently discarded. File sizes for WMA at 128k are roughly comparable to MP3 at the same bitrate, though wmav2 can achieve slightly better perceptual quality than older MP3 encoders at lower bitrates (64–96k). DRM (Digital Rights Management) can technically be embedded in WMA files, but FFmpeg does not apply or encode DRM — the output file from this tool will be DRM-free. Streaming metadata (such as stream titles) and standard ID3-equivalent tags are preserved where possible, but embedded album art from MP4 may not always survive the container transition intact.