Free online WMV to WEBM converter

Older Windows recordings, email attachments, and legacy editing exports may not play in browser-based HTML5 players that expect WebM. Converting them creates a browser-compatible file for web embedding, sharing, or editing, but usually requires video and audio re-encoding.

What the WMV format is

WMV (Windows Media Video) is a Microsoft video format used in older Windows Media Player libraries, Windows-based screen recordings, email attachments, and legacy editing software. A WMV file may contain WMV7, WMV8, WMV9, or VC-1 video with WMA audio. It remains common in older Windows archives, but support is less consistent on modern browsers, mobile devices, and non-Windows applications.

What the WEBM format is

WebM is an open media container designed primarily for web playback. It normally contains VP8, VP9, or AV1 video and Vorbis or Opus audio. Modern browsers and HTML5 players commonly support WebM without proprietary codecs. VP9 and AV1 can produce smaller files than older WMV encodings at comparable quality, although AV1 and VP9 encoding generally take longer than VP8.

How to convert the file

Using 101convert.com

1. Open the WMV-to-WebM converter on 101convert.com.
2. Upload the .wmv file.
3. Select WebM as the output format and start the conversion.
4. Download the resulting .webm file when processing finishes.

This method requires no installation, but uploading may be unsuitable for confidential or very large recordings.

Using FFmpeg

FFmpeg is suitable for local and batch conversion. After installing a current FFmpeg build, open a terminal in the source folder and run:

ffmpeg -i input.wmv -c:v libvpx-vp9 -crf 32 -b:v 0 -c:a libopus -b:a 128k output.webm

This uses VP9 video in constant-quality mode and Opus audio. For VP9, lower CRF values increase quality and file size; 30–36 is a reasonable starting range, but the best value depends on the source. Quote filenames containing spaces, such as "old recording.wmv".

To create a 720p file while preserving the aspect ratio, add a video filter:

ffmpeg -i input.wmv -vf "scale=-2:720" -c:v libvpx-vp9 -crf 32 -b:v 0 -c:a libopus -b:a 128k output.webm

Omit the filter to retain the source dimensions. FFmpeg normally retains the source frame rate unless an output frame-rate option is supplied.

For older WebM software that supports VP8 and Vorbis but not newer codecs, use:

ffmpeg -i input.wmv -c:v libvpx -crf 10 -b:v 0 -c:a libvorbis -q:a 5 output.webm

Using desktop software

Current versions of HandBrake can be used when their WebM output option is available: open the WMV through File → Open Source, choose WebM in the output format selector, select the video and audio codecs, choose a destination, and click Start Encode. If WebM is not listed in the installed version, use FFmpeg instead; renaming the extension does not perform a conversion.

Quality and compatibility limits

WMV-to-WebM conversion usually decodes and re-encodes the streams because the containers use different codec combinations. Re-encoding can reduce detail, and increasing the output resolution cannot restore detail already lost in the WMV source. Test the output in the browser or player that will be used for playback.

VP9 generally gives better compression than VP8 but encodes more slowly. Opus is the usual audio choice for current WebM playback; Vorbis is useful when compatibility with older WebM software is required. Browser support is broad for VP8 or VP9 with Opus or Vorbis, while support for AV1 depends more on the browser, device, and hardware.

Inspect files containing interlaced or variable-frame-rate footage, multiple audio tracks, subtitles, unusual metadata, or DRM. WebM may not retain every WMV-specific stream, subtitle, or metadata field, and FFmpeg cannot remove DRM. If subtitles are required, convert or add them separately using a format supported by the target player.