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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When the WebM and AV1 containers can both carry the same codec (H.264, H.265, VP9, AV1), the converter falls back to a remux: the elementary streams are copied byte-for-byte into the AV1 container and only the wrapper changes. A remux of a 1 GB WebM into AV1 typically finishes in 5-15 seconds with zero quality loss. 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 if the source shipped with a chapter list it was in a sidecar file — hand that to the converter and it gets written into the AV1.
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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Yes — every audio track in the WebM (director commentary, alternate languages, descriptive audio) is preserved in the AV1 when the target container supports multi-stream audio. MKV and MOV handle unlimited audio tracks; MP4 supports many but some hardware players only see track 1; WebM is capped at one Opus / Vorbis track. 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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Soft subtitles (selectable tracks) survive when AV1 can carry them: MKV holds SRT, ASS, SSA, PGS, VobSub natively; MP4 only holds mov_text (a stripped-down format). Converting an MKV with ASS styled subs to MP4 will typically downgrade them to mov_text or burn them in. Hardsubs (burned into the video) carry over regardless.
Does WebM to AV1 keep chapter markers / DVD-style navigation?
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Chapter metadata transfers between WebM and AV1 whenever both containers support a chapter atom (MKV, MP4, MOV). WebM stores chapters in a Matroska-compatible block, so MKV <-> WebM chapters round-trip cleanly. AVI has no chapter spec at all, so an AVI source arrives with no chapters to carry across and an AVI target cannot store the ones it was handed; add markers manually afterwards if you need them.
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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The default codec is chosen to match the AV1 container conservatively: MKV defaults to H.265 (HEVC) for better compression; MP4 defaults to H.264 for the widest device support; WebM defaults to VP9; AVI uses MPEG-4 ASP (DivX/Xvid lineage). Override via the advanced codec dropdown — AV1 is available for MKV / WebM where you want maximum compression and can wait through the encode.
How does HDR (HDR10, Dolby Vision) survive WebM to AV1?
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HDR static metadata (HDR10 mastering display values, max content light level) carries through to AV1 when both containers and the chosen codec support it (HEVC, AV1 in MKV / MP4). Dolby Vision is more fragile — DV profile 5 / 7 / 8.1 in WebM commonly survives only into MKV with HEVC; converting to an AV1 container that does not carry the DV layer flattens to HDR10.
Will the WebM to AV1 converter keep variable framerate (VFR)?
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MKV and WebM record real per-frame timestamps and handle VFR natively, so WebM VFR survives into an AV1 of those formats with no resampling. MP4 nominally stores timestamps too but some players assume CFR; the converter exposes a "force CFR" toggle that resamples VFR WebM to 24 / 30 / 60 fps AV1 for problematic targets.
