Can You Use AV1 Video Codec Inside WebM?

This article explores the compatibility between the AV1 video codec and the WebM container format. While WebM was originally designed for VP8 and VP9 video, development by the WebM Project has officially standardized the inclusion of AV1. Below, we break down how this integration works, its benefits, and current browser support.

Understanding AV1 and WebM Compatibility

The short answer is yes. The AV1 video codec is fully supported within the WebM (.webm) container.

The WebM format, maintained by Google, is an open, royalty-free media file format designed specifically for the web. Originally, WebM strictly restricted its video codecs to VP8 and VP9. However, because AV1 was developed by the Alliance for Open Media (AOMedia)—of which Google is a founding member—the WebM project updated its official specification to formally include AV1 video tracking alongside Opus and Vorbis audio.

Advantages of Using AV1 in WebM

Combining AV1 with WebM offers significant advantages for web developers and streaming platforms:

• Superior Compression: AV1 provides data compression that is roughly 30% more efficient than VP9 and H.265 (HEVC), allowing for higher-quality video at much lower bitrates.
• 100% Royalty-Free: Both the AV1 codec and the WebM container are completely open-source and royalty-free, eliminating the expensive licensing fees associated with formats like MP4/H.264 or HEVC.
• Optimized for Web Streaming: WebM is streamlined for HTML5 video playback, meaning AV1 videos inside a WebM container require less processing overhead to parse on web browsers than heavier container formats.

Browser and Ecosystem Support

While the integration is officially standardized, real-world playback depends on browser and hardware support.

For maximum cross-browser compatibility, many developers deploy AV1 within an MP4 (ISOBMFF) container as a fallback, or use HTML5 <video> source tags to serve WebM/AV1 to supporting browsers while serving older formats to legacy devices.