Convert WebM to WMA — Free Online Tool
Convert WebM files to WMA by extracting the Opus or Vorbis audio track and re-encoding it using the WMV2 (Windows Media Audio) codec. Ideal for making web-optimized audio content compatible with Windows-native media players and legacy Microsoft ecosystems.
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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
WebM files store audio in either the Opus or Vorbis codec inside a Matroska-based container. Neither of these codecs is natively supported by the WMA format, so this conversion performs a full audio transcode — the audio stream is decoded from Opus/Vorbis and then re-encoded using the wmav2 codec, Microsoft's second-generation Windows Media Audio implementation. Any video stream present in the WebM file is discarded entirely, since WMA is a pure audio format with no video container support. The output is a .wma file encoded at 128k bitrate by default, which is a standard quality level for WMA streaming content. Because both the input and output are lossy formats, this is a lossy-to-lossy transcode, meaning some additional audio quality degradation is unavoidable compared to transcoding from a lossless source.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool, the open-source multimedia processing engine that handles the decoding of the WebM input and encoding of the WMA output entirely within your browser via WebAssembly on this page. |
-i input.webm
|
Specifies the input file, a WebM container that typically holds video alongside Opus or Vorbis audio. FFmpeg reads this file and makes all available streams available for processing. |
-c:a wmav2
|
Sets the audio codec to wmav2, Microsoft's second-generation Windows Media Audio encoder. This tells FFmpeg to transcode the Opus or Vorbis audio from the WebM source into the WMA-compatible wmav2 format — a full re-encode, not a copy. |
-b:a 128k
|
Sets the audio output bitrate to 128 kilobits per second, which is the standard default quality level for WMA streaming audio. You can increase this value (e.g., 192k or 256k) to improve output quality at the cost of a larger file size. |
output.wma
|
Defines the output filename and its .wma extension, which tells FFmpeg to write the transcoded audio into a Windows Media Audio container. No video stream is written because WMA is an audio-only format. |
Common Use Cases
- Making WebM audio from a web browser recording compatible with Windows Media Player or legacy Windows applications that don't support Opus/Vorbis playback
- Preparing audio content for distribution on older Microsoft platforms or digital media systems that require WMA format, such as some Windows Phone or Zune-era devices
- Stripping the audio from a WebM video file — such as a downloaded HTML5 web video — and converting it to WMA for use in a Windows-based digital audio workflow
- Converting HTML5 game or web app audio assets from WebM to WMA so they can be used in Windows-native game engines or media frameworks that require WMA input
- Archiving or delivering audio content to corporate environments standardized on Microsoft media infrastructure where WMA is the accepted audio format
- Extracting a podcast or voice recording captured as WebM in a browser-based recorder and converting it to WMA for compatibility with Windows-based editing or playback software
Frequently Asked Questions
Yes, some quality loss is unavoidable. WebM audio is typically encoded with the Opus codec, which is already a lossy format. Converting to WMA (wmav2) requires decoding the Opus audio and re-encoding it into a different lossy codec, a process sometimes called generation loss. To minimize this, you can increase the output bitrate beyond the default 128k — WMA supports up to 320k — but you cannot fully recover quality that was already discarded by the original Opus encoding.
Basic metadata tags such as title, artist, and album may be carried over during the conversion if they were present in the WebM file, since WMA does support metadata tagging. However, WebM-specific metadata structures and any embedded chapter markers or subtitle tracks will be lost entirely, as WMA has no support for those features. You should verify metadata in the output file and re-tag it if needed using a tool like Mp3tag.
The video stream is completely dropped. WMA is an audio-only format with no container support for video, so FFmpeg automatically discards any video track present in the WebM source. Only the first audio stream is extracted and transcoded to wmav2. If your WebM file contains multiple audio tracks, only the default audio track will be included in the WMA output.
Replace the value after -b:a in the command to adjust the output bitrate. For example, to encode at 192k, use: ffmpeg -i input.webm -c:a wmav2 -b:a 192k output.wma. WMA supports bitrates from 64k up to 320k, with 128k being a reasonable default for general listening. Higher bitrates produce better audio fidelity but larger files. This is especially worth adjusting if your source WebM was encoded at a high Opus bitrate and you want to preserve as much of that quality as possible.
Yes, on the command line you can process multiple files using a shell loop. On Linux or macOS, run: for f in *.webm; do ffmpeg -i "$f" -c:a wmav2 -b:a 128k "${f%.webm}.wma"; done. On Windows Command Prompt, use: for %f in (*.webm) do ffmpeg -i "%f" -c:a wmav2 -b:a 128k "%~nf.wma". The browser-based tool on this page processes one file at a time, so the FFmpeg command is particularly useful when handling large collections.
wmav2 is Microsoft's improved second-generation WMA codec and offers better audio quality at equivalent bitrates compared to the older wmav1. Almost all software and hardware that supports WMA playback supports wmav2, making it the universally recommended choice. wmav1 exists mainly for compatibility with very old or niche legacy systems, and there is rarely a practical reason to use it for new conversions.
Technical Notes
The wmav2 codec used in this conversion is a fixed-bitrate lossy codec, unlike Opus which can operate in variable-bitrate mode and typically achieves superior perceptual quality at equivalent bitrates — especially below 128k. Because Opus is widely considered one of the most efficient audio codecs available, converting from Opus to wmav2 will generally result in a file that sounds worse at the same bitrate, not better. WMA also does not support multichannel audio beyond stereo in its standard profile, so any surround or multi-channel audio in the WebM source will be downmixed. The WMA format has no support for subtitles, chapters, or multiple audio streams, all of which WebM can carry natively. DRM can be applied to WMA files by external tools after conversion, but this FFmpeg command does not add any DRM. File size after conversion will vary depending on the source bitrate and duration, but a 128k WMA file is typically comparable in size to a 128k MP3 for the same content length.