A small overlay will appear in the top-left corner. In the "Codecs" line, you'll likely see something like av01.0.01M.08 (399) / opus (251) .
: This is a YouTube-specific itag (internal format ID) that typically corresponds to 1080p resolution AV1 video. The Audio Standard: Opus (251) Difference between 251 Opus and 141 mp4a? : r/YoutubeMusic codecs av01008m08 399 opus 251 new
Use MediaCapabilities API:
: This dictates the Level and Tier. The "08" corresponds to Level 4.0, which tells the hardware decoder the maximum processing limits (such as max pixel rate and frame size). The "M" stands for the Main Tier, used for standard playback applications (as opposed to High Tier for demanding enterprise applications). A small overlay will appear in the top-left corner
AV1 codec strings follow a strict pattern defined by the AV1 Codec ISO Media File Format Binding (AV1-ISOBMFF v1.2.0). Correct format: av01.N.xxM.yy The Audio Standard: Opus (251) Difference between 251
The combination of av01.0.08M.08 (399) opus (251) represents one of YouTube's highest-efficiency streaming configurations, frequently seen in the YouTube "Stats for Nerds" panel . This setup pairs the advanced video codec with the high-fidelity audio codec. Video: AV1 (av01.0.08M.08 / ID 399) This string identifies a specific stream profile for the AOMedia Video 1 (AV1)
