Extract Audio from WMV to WEBA — Free Online Tool
Extract audio from WMV video files and convert it to WEBA format, re-encoding the WMV's default WMA (wmav2) audio stream into Opus — a modern, highly efficient codec optimized for web streaming and browser playback. The result is a compact, browser-native audio file ideal for web applications and media players.
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FFmpeg Command
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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 audio using Microsoft's proprietary WMA (wmav2) codec inside an Advanced Systems Format (ASF) container. Since WEBA is a WebM-based audio-only container that exclusively supports Opus or Vorbis, the WMA audio must be fully decoded and re-encoded — it cannot be stream-copied. FFmpeg reads the WMV, discards the video stream entirely using the -vn flag, decodes the WMA audio, and then re-encodes it using the libopus encoder at 128k bitrate by default, packaging the result in a .weba container. This is a transcoding operation, not a remux, so some generation of quality loss is inherent, though Opus at 128k typically produces excellent perceptual quality.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool, which handles all the demuxing, decoding, encoding, and muxing required to extract and convert audio from the WMV container into WEBA format. |
-i input.wmv
|
Specifies the input WMV file. FFmpeg automatically detects the ASF container and identifies the contained video stream (typically msmpeg4) and audio stream (typically wmav2) without needing an explicit format flag on input. |
-vn
|
Disables video output, ensuring the msmpeg4 video stream from the WMV is completely discarded. Since WEBA is an audio-only format, this flag is required to prevent FFmpeg from attempting to include video in the output. |
-c:a libopus
|
Selects the libopus encoder to re-encode the WMA (wmav2) audio stream as Opus — the required and default codec for WEBA containers. Because WMA and Opus are incompatible, stream copying is not possible and full transcoding via libopus is mandatory. |
-b:a 128k
|
Sets the Opus audio output bitrate to 128 kilobits per second. Opus at 128k delivers high perceptual quality for both speech and music, and due to Opus's superior compression efficiency compared to WMA, this bitrate typically produces a smaller file than the source WMV audio at an equivalent or higher bitrate. |
-vn
|
A second instance of the video-disable flag, which is redundant but harmless in this command. It reinforces that no video stream should be written to the output, which is consistent with the audio-only nature of the WEBA container. |
output.weba
|
Specifies the output filename. The .weba extension signals to FFmpeg to use the WebM audio-only container format, which packages the Opus-encoded audio stream in a format natively supported by modern browsers for HTML5 audio playback. |
Common Use Cases
- Extract the audio commentary or narration from a WMV screen recording or training video to repurpose it as a standalone podcast or voiceover file for web publishing.
- Convert WMV files from a legacy Windows Media Player archive into WEBA for use in an HTML5 <audio> element, since browsers cannot natively play WMV or WMA.
- Strip the audio from a WMV surveillance or presentation recording to analyze dialogue or transcribe speech without needing the accompanying video.
- Prepare audio from corporate WMV webcasts or town hall recordings for embedding in a web-based internal communications portal that requires WebM-compatible formats.
- Extract music or sound effects from WMV content produced by older Windows-based video editors and deliver them as Opus-encoded WEBA files for low-latency web audio applications.
- Convert WMV audio tracks from DRM-free Windows Media files into a modern open format for long-term archival compatibility, replacing the proprietary WMA codec with open-standard Opus.
Frequently Asked Questions
Yes, some quality loss occurs because this is a transcode between two lossy formats — WMA (wmav2) is decoded from the WMV and re-encoded as Opus in the WEBA file. However, Opus is one of the most efficient audio codecs available, and at the default 128k bitrate it typically sounds transparent to most listeners for speech and music. If your source WMV has a high audio bitrate (e.g., 256k WMA), consider increasing the output Opus bitrate to 192k or 256k to better preserve perceived quality.
The WEBA container is a WebM audio-only format and is strictly limited to Opus or Vorbis encoded audio — it cannot carry WMA (wmav2) streams. Because the codecs are fundamentally incompatible at the container level, full decoding and re-encoding to Opus via libopus is mandatory. There is no way to avoid transcoding in this specific conversion.
Adjust the -b:a flag to set a different Opus bitrate. For example, replace -b:a 128k with -b:a 192k or -b:a 320k for higher quality, or -b:a 64k for a smaller file optimized for speech. The full modified command would look like: ffmpeg -i input.wmv -vn -c:a libopus -b:a 192k -vn output.weba. Opus performs exceptionally well even at lower bitrates compared to WMA, so 96k Opus is often comparable in quality to 128k WMA.
Yes, WEBA supports both Opus and Vorbis audio codecs. To use Vorbis, replace -c:a libopus with -c:a libvorbis in the command. However, Opus is generally preferred as the default because it outperforms Vorbis at most bitrates, especially below 128k, and has broader modern browser support. Use Vorbis only if you have a specific compatibility requirement for an older WebM-based workflow.
Some basic metadata may transfer, but WMV stores metadata in ASF-specific structures (such as WMA tag fields) that do not have a guaranteed mapping to the Matroska-based metadata format used by WEBA/WebM containers. In practice, common tags like title and artist often carry over, but embedded album art and Windows Media-specific attributes are typically lost. If metadata fidelity is important, verify the output with a tool like MediaInfo and re-tag the WEBA file manually if needed.
Yes, on the command line you can use a shell loop to process multiple files. On Linux or macOS, run: for f in *.wmv; do ffmpeg -i "$f" -vn -c:a libopus -b:a 128k -vn "${f%.wmv}.weba"; done. On Windows PowerShell, use: Get-ChildItem *.wmv | ForEach-Object { ffmpeg -i $_.FullName -vn -c:a libopus -b:a 128k -vn ($_.BaseName + '.weba') }. This browser-based tool processes one file at a time, so the FFmpeg command copied from this page is especially valuable for batch workflows on your local machine.
Technical Notes
WMV files use the ASF (Advanced Systems Format) container, which requires the special -f asf flag when creating WMV output — though on input, FFmpeg detects the format automatically. The default audio codec in WMV is wmav2 (Windows Media Audio 2), a proprietary Microsoft lossy codec. Since libopus and wmav2 are entirely incompatible at the codec level, this conversion always involves a full decode-encode cycle, unlike remux-based conversions such as MKV to MP4. WEBA is technically a WebM container restricted to audio, and FFmpeg enforces Opus or Vorbis as the only valid codecs; attempting to copy the WMA stream directly will produce an error. The -vn flag appears twice in the resolved command — once to suppress any video output stream during processing and once as a general safeguard — which is harmless but redundant; a single -vn is sufficient. Opus encoded at 128k in a WEBA file will typically be significantly smaller than the equivalent WMA audio at 128k due to Opus's superior compression efficiency, making WEBA an excellent choice for web delivery. Note that WEBA does not support multiple audio tracks, so if the source WMV contains multiple audio streams, only the default (first) stream will be extracted.