Step 1: Provide your WebM 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 AV1 files.
WebM to AV1 Conversion FAQ
How do I convert WebM to AV1 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 AV1 container without re-encoding it, MKV to MP4 among them, which is quick and loses no quality. Most pairs re-encode the video. WebM is deliberately narrow: VP8 or VP9 video (AV1 more recently) with Vorbis or Opus audio, and nothing else. AV1 is a codec, not a container — the bitstream normally travels inside MP4 or WebM, paired with Opus or AAC audio.
Can the AV1 hold more than one audio track?
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Yes, and it is a real upgrade over WebM. AV1 treats every audio stream as a first-class track, so an original-language mix, a dub and a director commentary can live in one file with the player switching between them on demand. AV1 delivers roughly 30% better compression than H.264 at the same quality and carries no licence fees, which is why YouTube and Netflix push it.
Does AV1 support chapter markers that WebM did not?
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It does. AV1 stores chapters as container metadata, so a long recording can be navigated by section instead of by scrubbing a progress bar. WebM has nowhere to put that information, so the converted AV1 starts with no chapters; add markers afterwards with a tool such as MKVToolNix or ffmpeg.
Will the AV1 still play smoothly on a phone or a TV?
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It may not. WebM is decoded by dedicated silicon on phones, tablets and TVs, which is why it plays without flattening the battery. AV1 typically falls back to software decoding on the same hardware — higher CPU load, a warmer device, and dropped frames on 4K material. For a device target, WebM is the safer container to stay in. AV1 encoding is slow, and hardware decoders only appeared in phones and TVs from about 2020 onward — older devices fall back to power-hungry software decoding.
Is AV1 a container or a codec, and does that change what I get back?
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It changes what to expect from the output file. One side of this conversion names an encoding rather than a wrapper, so what comes back is that bitstream inside whichever container suits it best — normally MP4 or MKV. The extension reflects the container; the codec is what actually determined the file size and where it will play.
Will multi-track audio survive WebM to AV1 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 AV1 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 WebM with that track first (VLC or ffmpeg can do this), then convert it. AV1 is the royalty-free video codec the Alliance for Open Media released in 2018 as the successor to VP9.
Are subtitle tracks preserved when converting WebM to AV1?
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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 WebM to AV1?
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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 WebM to AV1 drops these attachments when AV1 is not MKV — the elementary streams convert, but the attached payload stays in the source. Keep WebM as a backup if you depend on attached fonts.
Which codec does the AV1 output use by default?
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It depends on the AV1 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 WebM to AV1?
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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 WebM can look washed out in the AV1.
