Convert AVI to WebM Online
Convert legacy AVI files to modern web-optimized WebM format. Free, in your browser, no file uploads.
.avi · up to 100 MB
What you can do
AVI to WebM: modernize your legacy videos for today's web
HTML5 and browsers
WebM plays natively in Chrome, Firefox, Edge, and modern Safari without plugins or additional software.
100% private
Your AVI files never leave your device. Local processing via WebAssembly.
Archive and modernize
Convert 2000s DivX collections to a format with active support for years to come.
Progressive download
WebM supports native progressive streaming, ideal for web embedding without a dedicated streaming server.
How it works
Three steps, no hassle
Upload your AVI file
Drag or select your .avi file. Up to 500 MB. No signup or installs required.
VP8/Vorbis re-encoding in the browser
The AVI video (DivX, Xvid, MPEG-4) is re-encoded to VP8 and audio to Vorbis in the WebM container, in your browser.
Download your WebM
Modern video ready for HTML5 embedding, social media publishing, or cloud storage at a smaller size.
FAQ
Got questions?
Yes, in most cases. AVI files contain video encoded with MPEG-4 Part 2 (DivX, Xvid), H.264, or in older cases, MPEG-1/2 or the Microsoft Video 1 codec. Converting to VP8 requires complete decoding of the original video to uncompressed frames and re-encoding to VP8, introducing one generation of loss. The magnitude is controllable: with a VP8 bitrate equal to or higher than the original MPEG-4, the perceptual difference is minimal for resolutions up to 720p. For 480p DivX-era AVI files (the 700 MB 'CD rips'), conversion to 480p WebM at a similar bitrate produces a result perceptually equivalent to the original, with the advantage of a modern container playable in any browser.
For AVI files with DivX/Xvid (MPEG-4 Part 2), the resulting WebM VP8 will have a similar size to the original at comparable quality, since MPEG-4 Part 2 and VP8 have similar compression efficiency (both are second-generation lossy compression codecs, post-MPEG-2). The size advantage of WebM is more pronounced when the source AVI uses uncompressed PCM or MPEG-2 (older AVIs), where conversion to VP8 can reduce the size to one-fifth or one-tenth. For a 700 MB DivX AVI, the equivalent WebM will be between 600 and 800 MB depending on the target bitrate and resolution.
There are technical and practical reasons. Technically, WebM is completely patent-free (VP8 is under the BSD license since 2010, Vorbis and the Matroska/WebM container are equally free), while H.264 in MP4 has active MPEG LA patents (though royalties for free internet distribution were eliminated in 2016 for AVC). Practically, WebM is the preferred format for the HTML5 <video> tag in Chrome and Firefox, and is natively supported by Android. For archiving old DivX collections to be published on a website or shared via Discord/Telegram, WebM offers maximum compatibility with modern browsers without requiring additional software.
Chrome (since version 6, 2010), Firefox (since version 4, 2011), and Edge (since version 14, 2016) play WebM natively. Safari added VP8/WebM support in macOS Big Sur and Safari 14 (2020). iOS Safari has supported WebM since iOS 16 (2022). On Android devices, WebM is supported natively since Android 2.3. Desktop players like VLC, mpv, and MPC-HC play WebM without issues. Smart TVs with built-in browsers (LG WebOS, Samsung Tizen) support WebM in their recent versions. The only notable exception is Internet Explorer, with less than 1% market share in 2024.
AVI files are technically limited in multi-track support: the original AVI format (32-bit RIFF) only standardly supports one video and one audio track, though OpenDML (AVI 2.0) allows multiple audio tracks. Subtitles in AVI are typically external (separate .srt or .sub files) as the AVI container has very limited support for embedded subtitles. During conversion to WebM, the first audio track is extracted by default. The WebM container (derived from Matroska) supports multiple audio, video, and subtitle tracks, but adding all tracks would require a more advanced muxing tool.
Yes, that is one of the primary use cases. The resulting WebM video can be directly embedded in HTML5 with the <video> tag: <video controls><source src='video.webm' type='video/webm'></video>. For maximum compatibility including older Safari, it is recommended to also offer an MP4 version: <video controls><source src='video.webm' type='video/webm'><source src='video.mp4' type='video/mp4'></video>. WebM has the additional advantage of supporting progressive download more efficiently than AVI, as the WebM container index can be placed at the start of the file (unlike the AVI index which is typically at the end), allowing the browser to start playing the video while it loads.
Convert AVI to WebM: modernize legacy DivX video for HTML5 web
The AVI format was created by Microsoft in November 1992 as part of the Video for Windows kit to compete with Apple's QuickTime, which had been on the market for a year. In its first decade, AVI was the quintessential digital video format in the Windows ecosystem, used for everything from camera recordings to CD-ROM content distribution. The revolution that catapulted AVI to mass internet distribution came in the late 1990s with the emergence of the DivX codec: originally DivX was a hacked and modified version of Microsoft's proprietary MPEG-4 Version 3 codec, renamed and redistributed in 1998 by 'DVD Jon' (Jon Lech Johansen) and Jerome Rota. On top of this illegal codec, the legal alternative Xvid (DivX spelled backwards) quickly emerged — a completely free MPEG-4 Part 2 codec launched in 2001 by the open-source community. During the 1999–2010 period, AVI files with Xvid or DivX became the dominant format for film and series distribution on P2P networks (eMule, Kazaa, BitTorrent), creating an archive of tens of millions of files that today represent a preservation and accessibility challenge. WebM, developed by Google in 2010 from the Matroska container and the VP8 codec (acquired from On2 Technologies), represents the modern web standard for open video.
The technical conversion from AVI to WebM involves: demuxing the RIFF/AVI container to separate video and audio tracks, decoding the original video (MPEG-4 Part 2 with libxvid or libavcodec, H.264 with libx264 or libavcodec) to uncompressed YUV frames, encoding the frames to VP8 with libvpx using constant quality mode (CQ) to optimize quality-to-size ratio, and muxing the VP8 video and Vorbis audio into the Matroska-derived WebM container. VP8 was designed to be statistically comparable to H.264 Baseline: the reference study by Bankoski et al. (Google, 2011) published at VCIP 2011 showed that VP8 achieved quality comparable to H.264 Baseline at equivalent bitrates. Compared to MPEG-4 Part 2 (the DivX and Xvid codec, also called 'ASP' or Advanced Simple Profile), VP8 is generally superior in compression efficiency, since VP8 is a third-generation codec (2008) while MPEG-4 ASP is second-generation (1999). This means that for low-resolution DivX AVI files (480p, 320p), the resulting WebM can be smaller than the original AVI with equal or superior quality.
Modernizing legacy AVI files to WebM has multiple practical applications in 2025. The first is web publishing: AVI files are not natively playable in any modern web browser (Chrome, Firefox, Edge, Safari) without a plugin or prior download, while WebM plays directly in the HTML5 <video> element without dependencies. Converting collections of educational material, presentations, or recorded demonstrations from AVI to WebM makes them immediately embeddable in web portals, intranets, and e-learning platforms like Moodle or Canvas LMS. The second application is file compression: DivX-era MPEG-4 Part 2 AVI files can be additionally compressed by 10–30% when re-encoded to VP8 at the same perceptual quality level, thanks to the greater efficiency of the modern VP8 encoder versus the 1999-era MPEG-4 Part 2. The third application is compatibility with modern services: platforms like Discord, Notion, Confluence, and modern CMS natively support WebM for video embedding, while AVI requires prior conversion or is not accepted. Convertir.ai performs all AVI→WebM conversion in the browser via WebAssembly, without servers or usage limits.