Step 1: Transfer your WMV files using the button above or by slide and deposit.
Step 2: Click the 'Convert' button to start the conversion.
Step 3: Retrieve your converted WebM files.
WMV to WebM Conversion FAQ
How do I re-encode WMV to WebM without losing video quality?
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Upload your WMV file and set Quality to High Quality in the conversion options. That re-encodes the video at the highest quality setting (CRF 18 for H.264 and VP9 output), which keeps the most detail at the cost of a larger file. The default, Balanced, uses the standard setting. The WebM output gets a codec its container supports: H.264 for MP4, MOV and MKV, VP9 for WebM. WMV carries Microsoft’s own VC-1 or WMV3 video with WMA audio — codecs almost nothing outside Windows decodes natively. WebM is deliberately narrow: VP8 or VP9 video (AV1 more recently) with Vorbis or Opus audio, and nothing else.
My WMV footage shows comb lines on movement — will that carry into the WebM?
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Yes. WMV content is often interlaced, because the format comes from the broadcast and DVD era, and this converter has no deinterlace option, so the combing carries into the WebM. If it matters, deinterlace the WMV first in a desktop tool such as HandBrake or ffmpeg (the yadif filter). WMV is Windows Media Video, Microsoft’s ASF-based format from the Windows XP era.
Can I add selectable subtitles once the file is WebM?
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Yes. WMV has no usable soft-subtitle track, so subtitles for WMV content had to be burned into the picture or shipped as a separate sidecar file. WebM carries subtitles as their own selectable stream, so after conversion you can attach an SRT track the viewer can switch on, switch off or restyle.
Why does my WMV file fail to convert to WebM?
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Almost always DRM. Some WMV files are encrypted at the bitstream level by the store or software that issued them, and an encrypted stream cannot be decoded by us or by anything else without the licence key. Files you recorded, exported or downloaded unprotected convert normally; a licensed purchase will not, and no converter can honestly promise otherwise. WMV is effectively a dead end: macOS, iOS, Android and every browser need third-party decoders, and some WMV files carry DRM that cannot be converted at all.
Will the WebM play in a browser when the WMV would not?
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Yes, and that is usually the whole reason for the conversion. A WMV embedded in a web page either shows a broken player or forces a download, because browsers ship no decoder for it. WebM plays inline through the native HTML5 video element with no plugin and no external application. WebM plays natively in every modern browser with no plugin, no licence fee and no patent exposure, which makes it the default for web-embedded video.
Is it worth converting old WMV recordings to WebM at all?
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For anything you intend to keep, yes. WMV belongs to an earlier generation of video tooling and the software that reads it is steadily disappearing from phones, browsers and operating systems. Moving the footage to WebM now, while a clean decoder still exists, is the difference between an archive you can open in ten years and one you cannot.
Which video codec does the WebM output use?
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It depends on the WebM container. MP4, MOV and MKV output use H.264, which plays on practically every phone, browser and TV. WebM output uses VP9. AVI, WMV and MPEG output use the older codecs those formats were designed for. WebM is a strict subset of Matroska that Google published in 2010 specifically to give HTML5 video a royalty-free container.
Will my audio track survive WMV to WebM conversion?
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Yes, the main audio track comes through, re-encoded to a codec the WebM container plays, for example AAC in MP4 and MOV or Opus in WebM. Most conversions keep only that one track (the one with the most channels), so alternate languages and commentary are dropped. MP4 to MOV, and AVI, WMV, MPEG, FLV, VOB or M4V to MKV, keep every audio track.
Can I keep the original framerate when converting WMV to WebM?
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Yes. The frame rate is kept unless you change it: a 24 fps WMV stays 24 fps in the WebM. The Frame Rate setting can also convert to 60, 30 or 24 fps. It changes the rate only; it does not deinterlace the video or remove 3:2 pulldown.
How much will the file size change going from WMV to WebM?
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It depends on what happens to the video. MKV to MP4 or MOV with the default settings copies the video stream unchanged, so the size stays close to the source. Most other pairs re-encode it: a high-bitrate WMV usually comes out smaller, while an already heavily compressed one can grow. Smaller File under Quality gives the smallest output, and H.265 in the Codec setting (MP4, MOV and MKV) is usually smaller than H.264 at similar quality but plays on fewer devices.
Will the WebM file play on iPhone, Android, and Smart TVs?
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MP4 with H.264 plays on practically every phone, browser and TV. MOV with H.264 plays on Apple devices and most TVs but not on every older Android phone. MKV needs an app such as VLC on iOS, and WebM is at home in browsers. There is no device preset on this page, so choose the target format your device supports. WebM is a poor fit anywhere outside a browser — video editors, phones’ native galleries and Smart TVs largely ignore it.
How long does converting a 1-hour WMV video to WebM take?
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There is no fixed time: it depends on the length, the resolution and the target format. Conversions run on our servers' CPUs with software encoders; there is no GPU acceleration. MKV to MP4 or MOV with the default settings copies the video stream and is the quickest. A re-encode to H.264 takes longer, and WebM (VP9) is the slowest target, several times slower than H.264 in our tests.
