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WebCodecs Standardizes AV1/AVIF Handling Between Chrome and Firefox

22 September 2026

In a significant step toward a unified browser-media ecosystem, recent technical updates are aligning codecs and media APIs in Chrome and Firefox. The newest implementations are nearly identical not only on a standards-API level in WebCodecs, but also at a deeper decode implementation level with AV1 and AVIF.

WebCodecs is the unifying foundation for this convergence. Mozilla's Firefox 130 and the Chromium-based browsers now fully support the WebCodecs API, a low-level media interface for directly manipulating audio and video streams.

This shared API enables a common path for developers working with AV1 video and AVIF image formats across browsers.

Shared libraries behind the scenes

Beyond the application-facing API, Firefox and Chrome are moving to use the same underlying codecs via shared libraries. In an update published in late September, browser-engines analyst Artem Ivanov at TestMu AI stated that Chrome and Firefox now access the same hardware backends for AV1 video decode, primarily using the libdav1d library. TestMu's analysis of WebCodecs change logs confirmed that developers in both browser projects are converging on libdav1d and libx264.

For AVIF images, the same trend is apparent. Mozilla adopted libdav1d as the default AV1 decoder via the image.avif.use-dav1d preference, and Firefox's AV1 codec parsing has grown to seamlessly integrate with libdav1d and enable more robust hardware decode on modern AV1-capable hardware.

This underlying framework brings tangible benefits for developers. WebCodecs provides an unambiguous portal to browser audio and video encoders/decoders, and it can utilize hardware-accelerated codecs like AV1 if the operating system's GPU media stack is available. When hardware decoding is unavailable, browsers can default to software decoding.

AV1 adoption expanding

Support for the AV1 codec is growing. TestMu AI's analysis found that AV1 availability in modern browsers is now widespread, with October 2023 data showing AV1 decoding effectively universal on the desktop and Android versions of Chrome, Edge, and Firefox.

One area still needing work is AV1 on Apple devices. The WebCodecs codec analysis data shows Safari remains the notable holdout for AV1, with only 24% of macOS Safari sessions and 33% of iOS Safari sessions having AV1 decode capability. This highlights the core difference across Safari's underlying codec backend and other modern browsers using libdav1d.

Now that Chrome and Firefox are sharing more of their media decoding at a code level, cross-browser parity for media APIs comes next. Independent analysis has found that Firefox has implemented its Vulkan Video decoding support, an additional AV1 decode path optimized for hardware acceleration.

Together, these developments make AV1 increasingly viable for production use in modern browsers. "There's a long way to go," Igor Kordov writes in a blog post published alongside the Firefox Vulkan Video announcement, "but this is a big step toward a simpler, faster internet without all the old-codec compromises."

For developers working with WebCodecs and AV1, this unification could be a productivity boost, reducing the need for browser-specific code. For creators of AV1 content, whether niche projects or major commercial ventures, consistent AV1 support is enabling more ambitious, high-quality media experiences.