Codecs Av01008m08 399 Opus 251 New May 2026

The string refers to the AOMedia Video 1 (AV1) codec, a royalty-free, open-source video format developed by the Alliance for Open Media .

This is the identifier for the AV1 codec. It is designed to be up to 50% more efficient than older standards like H.264. codecs av01008m08 399 opus 251 new

These are internal parameters. "0" typically refers to the Main Profile, "08M" indicates the bit depth (8-bit) and level, and the final digits represent specific encoding tiers used by YouTube's servers. The string refers to the AOMedia Video 1