Extract Audio from WMV to AC3 — Free Online Tool
Extract and convert the WMV audio track to AC3 (Dolby Digital), dropping the video entirely and re-encoding the WMV Audio v2 (wmav2) stream into the AC3 codec used by DVDs, Blu-rays, and broadcast systems. Ideal for repurposing Windows Media content into professional surround-sound pipelines.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your WMV file here
or click to browse
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
WMV files typically carry audio encoded with Microsoft's proprietary wmav2 codec inside an ASF (Advanced Systems Format) container. Since AC3 is a completely different codec developed by Dolby, a full audio transcode is required — the wmav2 audio is decoded to raw PCM in memory and then re-encoded using Dolby's AC3 encoder at the target bitrate (192k by default). The video stream is discarded entirely using the -vn flag, so no video decoding work is performed. The result is a standalone .ac3 file containing only Dolby Digital audio, ready for use in DVD authoring, broadcast workflows, or home theater systems.
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.wmv
|
Specifies the input WMV file. FFmpeg reads the ASF container, identifies the msmpeg4/msmpeg4v2 video stream and the wmav2 audio stream, but only the audio will actually be processed in this command. |
-vn
|
Disables video output entirely, telling FFmpeg to skip the WMV video stream (msmpeg4 or msmpeg4v2) without decoding it. This is what makes the output a pure audio file rather than a video file. |
-c:a ac3
|
Sets the audio encoder to Dolby's AC3 (Dolby Digital) codec, which fully re-encodes the wmav2 audio from the WMV source into the AC3 format required by DVDs, Blu-rays, and broadcast systems. |
-b:a 192k
|
Sets the AC3 audio bitrate to 192 kilobits per second, a standard quality level suitable for stereo Dolby Digital audio. Higher values like 384k or 448k are recommended for multichannel 5.1 content or when maximum fidelity is needed. |
output.ac3
|
Names the output file as a raw AC3 elementary stream. The .ac3 extension signals to FFmpeg — and to downstream tools like DVD authoring software or MPEG muxers — that the file contains a bare Dolby Digital audio track with no container wrapper. |
Common Use Cases
- Pull the audio from a Windows Media video recording of a live concert or event and deliver it as a Dolby Digital AC3 track for inclusion in a DVD or Blu-ray authoring project.
- Extract commentary or narration recorded in WMV format from a Windows-based screen recorder and convert it to AC3 for use in a broadcast or streaming delivery pipeline that mandates Dolby Digital.
- Strip the audio from a WMV training video distributed via Windows Media Player and convert it to AC3 for embedding as a discrete audio track in professional video editing software like Adobe Premiere or DaVinci Resolve.
- Convert archived WMV news footage audio to AC3 so it can be muxed into an MPEG-2 transport stream for television broadcast, which commonly requires Dolby Digital audio.
- Extract the wmav2-encoded audio from a WMV file received from a Windows-centric corporate environment and transcode it to AC3 to feed a home theater receiver or AV processor that supports Dolby Digital but not Microsoft's proprietary codec.
- Repurpose WMV-format video game cutscene audio into AC3 for inclusion in a fan-made DVD compilation, where the AC3 format is required by the DVD Video specification.
Frequently Asked Questions
Yes — this is a lossy-to-lossy transcode, which means two generations of compression artifacts are introduced. The wmav2 audio in the WMV file was already compressed using Microsoft's codec, and re-encoding it to AC3 applies a second round of Dolby Digital compression on top of that. To minimize quality degradation, use the highest bitrate that suits your use case; 192k is a reasonable default, but 384k or higher will preserve more of the original fidelity if your downstream system supports it.
AC3 supports stereo (2.0) and full 5.1 surround sound, but what you get in the output depends entirely on the channel layout in your WMV source. Most WMV files contain stereo wmav2 audio, so the AC3 output will also be stereo unless the source contains a discrete multichannel mix. AC3's real strength — 5.1 surround — is only realized if your source audio actually has six channels; this tool cannot synthesize surround from a stereo WMV file.
Yes — replace '192k' in the command's '-b:a 192k' flag with any AC3-compatible bitrate: 96k, 128k, 192k, 256k, 320k, 384k, 448k, or 640k. The AC3 specification caps at 640k. For stereo content, 192k–256k is generally transparent; for 5.1 surround, 384k–448k is the broadcast standard. Note that very low bitrates like 96k can introduce audible artifacts, especially on audio that was already compressed as wmav2.
The .ac3 extension denotes a raw Dolby Digital elementary stream — it contains only the AC3-encoded audio data with no additional container wrapper. This is the format expected by DVD and Blu-ray authoring tools, MPEG muxers, and broadcast encoders when they ask for a 'Dolby Digital audio track.' If you need the audio wrapped in a standard container like MKV or MP4 for general playback, you can change the output filename to output.mkv or output.mp4 and FFmpeg will mux the AC3 stream into that container automatically.
The video stream is completely discarded. The '-vn' flag tells FFmpeg to ignore all video data in the WMV file, so the msmpeg4 or msmpeg4v2 video codec is never decoded. This makes the conversion significantly faster than a full video transcode and produces a much smaller output file containing only the AC3 audio.
Yes. On Linux or macOS, you can run: for f in *.wmv; do ffmpeg -i "$f" -vn -c:a ac3 -b:a 192k "${f%.wmv}.ac3"; done. On Windows Command Prompt, use: for %f in (*.wmv) do ffmpeg -i "%f" -vn -c:a ac3 -b:a 192k "%~nf.ac3". This loops through every WMV file in the current directory and extracts its audio as a separate AC3 file, which is practical when processing large archives of Windows Media content.
Technical Notes
WMV files use the ASF (Advanced Systems Format) container, which requires the '-f asf' flag when FFmpeg cannot detect the format automatically, though this is rarely needed when the file has a standard .wmv extension. The default audio codec in WMV is wmav2, a proprietary Microsoft codec that is not natively understood by most professional broadcast or disc-authoring tools — hence the value in transcoding to AC3. The AC3 codec (Dolby Digital) is defined by the ATSC and DVD Video specifications, making the output directly compatible with standard-definition DVD authoring, MPEG-2 transport stream muxing, and many AV receivers. One important limitation: AC3 does not support more than 5.1 channels (6 channels max), and FFmpeg's AC3 encoder does not pass through arbitrary metadata from the ASF container such as title or author tags, so metadata from the WMV source will not appear in the AC3 output. Additionally, WMV files with DRM (Digital Rights Management) protection cannot be processed by FFmpeg or this tool, as the encrypted media cannot be decoded.