Convert WMV to WEBA — Free Online Tool
Convert WMV video files to WEBA audio by extracting and re-encoding the Windows Media Audio stream into Opus format inside a WebM container. This is ideal for stripping video from WMV recordings and producing a lightweight, web-optimized audio file using one of the most efficient modern audio codecs available.
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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 typically carry audio encoded with WMA (Windows Media Audio), a Microsoft proprietary codec. Since WEBA is an audio-only format, the video stream is completely discarded during this conversion — not copied, just dropped. The WMA audio is then decoded and re-encoded from scratch into Opus using libopus, wrapped inside a WebM container with the .weba extension. This is a full transcode of the audio: WMA is decoded to raw PCM internally, then Opus compression is applied at 128k bitrate by default. Opus is a modern, royalty-free codec developed by Xiph.Org and standardized by IETF, offering better audio quality per kilobit than WMA, AAC, or MP3 at comparable bitrates. No video metadata, chapter data, or subtitle information is preserved, as the WEBA format supports none of these.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg multimedia processing tool. In this browser-based tool, FFmpeg runs locally via WebAssembly (ffmpeg.wasm) so no files leave your device. The same command works identically on a desktop FFmpeg installation for files over 1GB. |
-i input.wmv
|
Specifies the input file — a WMV (Windows Media Video) file in Microsoft's ASF container format. FFmpeg reads and demuxes both the video and audio streams from this file, making them available for processing. |
-c:a libopus
|
Sets the audio encoder to libopus, which produces Opus-encoded audio — the default and required codec for WEBA output. Since WMA audio from the WMV source cannot be copied directly into a WebM container, this forces a full transcode from WMA to Opus. |
-b:a 128k
|
Sets the target audio bitrate to 128 kilobits per second for the Opus encoder. Opus at 128k delivers excellent quality for both music and speech, generally outperforming WMA or MP3 at the same bitrate. Increase this value (e.g., 192k or 256k) to reduce generation loss from the WMA-to-Opus transcode. |
-vn
|
Disables video output entirely, telling FFmpeg to ignore all video streams from the WMV file. This is required because WEBA is an audio-only container with no support for video codecs — without this flag, FFmpeg would attempt to include video and produce an error or invalid output. |
output.weba
|
Defines the output filename with the .weba extension, which signals a WebM container holding only audio (Opus in this case). FFmpeg infers the container format from this extension and writes the Opus-encoded audio stream into a valid WEBA file. |
Common Use Cases
- Extract the audio commentary from a WMV screen recording or tutorial video to distribute as a standalone audio file for web playback or podcasting
- Pull the audio track from a WMV presentation recorded in Windows Media Player or older Microsoft tools and convert it into a browser-compatible format for embedding on a webpage
- Archive spoken-word WMV content — lectures, interviews, or conference recordings — as compact WEBA files using Opus compression to save storage while maintaining intelligibility
- Convert legacy WMV media library files to WEBA for use in modern web applications, since Opus/WebM is natively supported in Chrome, Firefox, and Edge without plugins
- Strip the audio from a DRM-free WMV video file and produce a low-latency Opus stream suitable for use in WebRTC or real-time web audio applications
- Repurpose WMV video content as audio-only WEBA files for mobile web experiences where downloading a full video would be unnecessarily bandwidth-heavy
Frequently Asked Questions
Because the audio is transcoded — decoded from WMA and re-encoded to Opus — there is a generation loss involved. However, Opus at 128k (the default) typically sounds as good as or better than WMA at the same bitrate due to Opus's superior compression efficiency. If your original WMV file has a high-quality WMA audio track, the WEBA output at 128k will be transparent for most listening scenarios. For critical archiving, you can increase the bitrate to 192k or 256k to minimize any perceptible quality difference.
The dramatic size reduction comes from two factors: the video stream (which typically accounts for 80–95% of a WMV file's size) is completely removed, and the remaining audio is re-encoded using Opus, which is among the most efficient audio codecs available. A 500MB WMV video file might produce a WEBA file of only a few megabytes, depending on the audio length and bitrate. This is expected behavior — you are extracting only the audio content.
No. WMA (Windows Media Audio) is a Microsoft proprietary codec and is not compatible with the WebM/WEBA container format, which only supports Opus and Vorbis. The audio must be fully decoded and re-encoded into Opus. There is no way to stream-copy WMA audio into a WEBA file — the transcode step is mandatory for this format pair.
Yes, WEBA files using Opus audio have native playback support in all major modern browsers including Chrome, Firefox, Edge, and Opera. Safari added Opus/WebM support in Safari 15 (released 2021), so current versions handle it as well. The WEBA format was specifically designed for web delivery, making it a strong choice for HTML5 audio elements and web application use.
Replace the value after -b:a in the command. For example, to encode at 192k instead of the default 128k, use: ffmpeg -i input.wmv -c:a libopus -b:a 192k -vn output.weba. Available options are 64k, 96k, 128k, 192k, 256k, and 320k. Opus is remarkably efficient at low bitrates — 64k is often sufficient for speech content like lectures or podcasts, while 192k is considered transparent for most music. Note that Opus does not benefit much above 256k, so 320k rarely adds perceivable quality.
Yes, you can batch process multiple WMV files using a shell loop around the FFmpeg command. On Linux or macOS: for f in *.wmv; do ffmpeg -i "$f" -c:a libopus -b:a 128k -vn "${f%.wmv}.weba"; done. On Windows Command Prompt: for %f in (*.wmv) do ffmpeg -i "%f" -c:a libopus -b:a 128k -vn "%~nf.weba". This is particularly useful for large batch conversions of legacy WMV media libraries, and it runs entirely locally so there are no file size or count restrictions.
Technical Notes
WMV files are built on Microsoft's Advanced Systems Format (ASF) container and use the -f asf flag internally in FFmpeg to ensure correct demuxing. The audio codec in most WMV files is WMA version 2 (wmav2), though some WMV files may contain AAC or even MP3 audio. Regardless of the source audio codec, all audio must be re-encoded to either Opus or Vorbis to fit inside a WEBA container — libopus is the default and preferred choice due to its superior performance across all bitrate ranges. WEBA does not support multiple audio tracks, so only the first audio stream from the WMV file will be included in the output; secondary audio tracks are silently dropped. The -vn flag is essential here and ensures FFmpeg skips all video streams entirely rather than attempting to encode them, which would fail since WEBA has no video codec support. Any DRM (Digital Rights Management) protection on the WMV file will prevent FFmpeg from reading it — only DRM-free WMV files can be processed. Metadata such as title or artist tags stored in the ASF container may not be fully transferred to the WEBA output, as ASF and WebM use different metadata schemas with limited cross-mapping support.