Use MediaCapabilities API:
codec, an open-source, royalty-free format designed to deliver high-quality video at significantly lower bitrates than older codecs like H.264 (AVC) or VP9. : Indicates the AV1 codec using Profile 0 (Main) : Represents the corresponds to . This level supports resolutions up to 1080p at 30fps. : Refers to the 8-bit depth for color. : This is the YouTube-specific Format ID (itag) , typically used for video streams. Audio: Opus (251) Opus (251) codecs av01008m08 399 opus 251 new
The string refers to the AOMedia Video 1 (AV1) codec, a royalty-free, open-source video format developed by the Alliance for Open Media . Use MediaCapabilities API: codec
But your string merges them – possibly a combined representation entry. codecs av01008m08 399 opus 251 new
: High-definition streaming (1080p and 4K) at lower bitrates.