Step 1: Provide your M4V files using the button above or by toss and let go.
Step 2: Click the 'Convert' button to start the conversion.
Step 3: Fetch your converted WebM files.
M4V to WebM Conversion FAQ
How do I convert M4V to WebM without re-encoding the video stream?
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There is no stream-copy switch on this page. A few pairs copy a compatible video stream into the WebM container without re-encoding it, MKV to MP4 among them, which is quick and loses no quality. Most pairs re-encode the video. Structurally an M4V is an MP4 — H.264 or HEVC with AAC — with optional Apple FairPlay DRM and iTunes chapter metadata. WebM is deliberately narrow: VP8 or VP9 video (AV1 more recently) with Vorbis or Opus audio, and nothing else.
My M4V has several audio tracks — do they all survive into the WebM?
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No. The converter keeps one audio track, the one with the most channels (normally the main mix), and drops the rest; there is no setting to pick a different one. To keep another track, remux the M4V with that track first (VLC or ffmpeg can do this), then convert it. M4V keeps chapter markers, artwork and subtitle tracks in the shape the Apple TV app expects, which plain MP4 often loses. WebM is a poor fit anywhere outside a browser — video editors, phones’ native galleries and Smart TVs largely ignore it.
Why does my M4V file fail to convert to WebM?
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Almost always DRM. Some M4V 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. DRM-protected M4V purchases cannot be converted by anything; only unprotected M4V files are convertible, and non-Apple players often need the extension renamed.
Will the WebM play in a browser when the M4V would not?
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Yes, and that is usually the whole reason for the conversion. An M4V 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.
Both M4V and WebM are modern containers — which should I actually keep?
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Keep whichever matches where the file is going, because neither is better in the abstract. One of these two is built for playback compatibility and the other for holding everything a file might contain, and they trade against each other exactly along that line. The pragmatic answer for most libraries is to archive in the feature-rich container and export to the compatible one on demand.
Will multi-track audio survive M4V to WebM conversion?
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Usually not. Most conversions keep one audio track, the one with the most channels (normally the main mix), re-encoded for the WebM container, so commentary and alternate-language tracks are dropped. AVI, WMV, MPEG, FLV, VOB and M4V to MKV keep every track, and so does MP4 to MOV. To keep a different track, remux the M4V with that track first (VLC or ffmpeg can do this), then convert it. WebM is a strict subset of Matroska that Google published in 2010 specifically to give HTML5 video a royalty-free container.
Are subtitle tracks preserved when converting M4V to WebM?
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On some pairs. MP4 to MOV keeps every text subtitle track. AVI, WMV, MPEG, FLV, VOB and M4V to MKV keep every subtitle track: text subtitles are copied or converted to SRT, and picture-based subtitles such as DVD or Blu-ray ones are copied as they are. MP4, MOV and WebM to MKV keep only the first subtitle track (as ASS), and MP4 to WebM keeps the first one as WebVTT. Other pairs, including MKV to MP4 or MOV and WebM to MP4, drop subtitle tracks, and the converter does not burn them into the picture. Subtitles that are already burned in stay, because they are part of the video frames.
What about MKV attachments (fonts, cover art) when going M4V to WebM?
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MKV is the only mainstream container that stores arbitrary attached files (TTF fonts for ASS subs, JPG cover art, fan-translated PDF inserts). Going from M4V to WebM drops these attachments when WebM is not MKV — the elementary streams convert, but the attached payload stays in the source. Keep M4V as a backup if you depend on attached fonts.
Which codec does the WebM output use by default?
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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.
How does HDR (HDR10, Dolby Vision) survive M4V to WebM?
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There is no HDR processing or tone mapping. When the video stream is copied (MKV to MP4 or MOV with the default settings), HDR10 passes through as it is. When the video is re-encoded, the HDR10 mastering metadata is dropped and Dolby Vision or HDR10+ data is not kept, and with a Quality, Resolution or Frame Rate setting some pairs also reduce the video to 8-bit colour, so an HDR M4V can look washed out in the WebM.
