Convert AVI to WebM
Convert AVI video files to WebM format directly in your browser. WebM with VP9 video and Opus audio is the modern open standard for HTML5 <video> — typically 30-50% smaller than the same content in an AVI container. No upload needed.
Drag 'n' drop files here, or
click to select files
.avi
Drop your files and click Convert to get WEBM
//when_to_use
When to Convert AVI to WebM
- Modernizing old AVI camcorder archives to WebM for embedding in family history WordPress sites
- Converting AVI training videos to WebM for HTML5 <video> on internal documentation portals
- Shrinking AVI screen recordings to WebM for embedding in GitHub READMEs and Markdown docs
- Converting Xvid/DivX AVI rips to WebM for self-hosted media servers like Jellyfin and Plex web players
- Migrating legacy AVI corporate video assets to WebM for use as autoplay backgrounds on modern landing pages
//comparison
AVI vs WEBM
| Property | AVI | WEBM |
|---|---|---|
| Container | AVI (RIFF, 1992) | WebM (Matroska subset) |
| Video codec | H.264 / Xvid / DivX / MJPEG | VP9 (CRF 32) |
| Audio codec | MP3 or PCM | Opus 96kbps |
| File size | Baseline | 30-50% smaller |
| HTML5 <video> support | No | Chrome, Firefox, Edge native |
| Best for | Legacy Windows software | Web embedding, royalty-free |
//how_it_works
How It Works
Drop your AVI files
Drag and drop or select AVI files. First use loads FFmpeg WASM (~30MB).
FFmpeg decodes the AVI
FFmpeg WASM parses the AVI container and decodes whatever codec is inside (H.264, Xvid, DivX, MJPEG) along with the MP3/PCM audio.
VP9 + Opus encode
Video is re-encoded with libvpx-vp9 at CRF 32; audio with libopus at 96kbps. Streams are muxed into the WebM container.
Download your WebM files
Your WebMs are ready for HTML5 <video>, Chrome, Firefox, Edge, and any modern web embed.
// under the hood
AVI is the legacy Microsoft Audio Video Interleave container, holding any of H.264, Xvid, DivX, or MJPEG video with MP3 or PCM audio. WebM is the open container restricted to VP8/VP9 video and Vorbis/Opus audio. Our converter uses FFmpeg WASM to demux the AVI input, decode whatever codec is inside to raw frames and PCM, then re-encode video with libvpx-vp9 at CRF 32 (deadline=good) and audio with libopus at 96kbps before muxing into the WebM container.
//faq
Frequently Asked Questions
- Why convert AVI to WebM?
- AVI is a 1992 container — fine for legacy Windows tools but a poor fit for the modern web. WebM with VP9 + Opus is what Chrome, Firefox, and Edge prefer for HTML5 <video>, and it gives you 30-50% smaller files than the equivalent AVI. If you're moving an old AVI archive onto a website, WebM is the right destination format.
- What codecs end up inside the WebM?
- We encode video with VP9 at CRF 32 using libvpx-vp9 and audio with Opus at 96kbps using libopus. VP9 + Opus is the modern WebM combination supported across every current browser.
- How big a quality drop should I expect?
- AVIs vary widely — some hold high-quality H.264, others hold older Xvid/DivX or MJPEG. Re-encoding to VP9 at CRF 32 is visually transparent for clean H.264 sources. For older Xvid/DivX or MJPEG sources the result will look the same or slightly better, since CRF 32 VP9 outperforms those codecs.
- Why is the encoding slow?
- VP9 is significantly heavier than H.264 to encode. FFmpeg WASM is single-threaded inside the browser, so expect roughly 0.05-0.2x realtime — a 1-minute AVI may take 5-20 minutes. For long files our desktop app uses native FFmpeg with multi-threading.
- Are my AVI files uploaded?
- No. FFmpeg WASM runs entirely in your browser tab. Your AVI files never leave your device.
//related_converters
Related Converters
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→Convert MP4 to MP3
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→Convert MOV to MP4
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→Convert WebM to MP4
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→