While "399" handles the pixels, opus 251 handles the sound. This is arguably the most interesting part of the string.
This string selects or describes an Opus audio stream (ID 251, codec opus) combined with an experimental video track av01008m08 , track ID 399, marked as new . codecs av01008m08 399 opus 251 new
: These numbers provide detailed specifications about the stream's requirements: While "399" handles the pixels, opus 251 handles the sound
The combination of these two codecs represents a "new" draft for the future of the web. By reducing the data footprint of high-quality media, platforms can reach users in regions with limited infrastructure without sacrificing the viewing experience. Furthermore, because both AV1 and Opus are royalty-free, they foster an open ecosystem where developers can innovate without the burden of licensing fees. This synergy ensures that as we move toward more immersive digital experiences, the underlying technology remains both powerful and accessible. : These numbers provide detailed specifications about the
Looking forward, the codec revolution isn't over. is on the horizon, with its first major release finalized in May 2026 promising even greater compression gains. Simultaneously, the 6G era is driving the development of entirely new video coding standards by Nokia, Ericsson, and Fraunhofer HHI, expected around 2030, built for immersive media like AR/VR. On the audio side, the industry is seeing rapid innovation in neural audio codecs that use AI for astonishingly efficient compression at very low bitrates.
Use MediaCapabilities API:
: Indicates Level 3.1 operating at a Main tier data rate. Levels define the maximum processing limits, such as resolution and frame rate. Level 3.1 typically handles standard 720p or 1080p video resolutions at smooth frame rates. 08 : Represents an 8-bit color depth .