https://blog.paul.cx/post/audio-video-synchronization-with-t... has some background, https://github.com/w3c/webcodecs/blob/main/samples/lib/web_a... is part of a full example that you can run using web codecs, web audio, audioworklet SharedArrayBuffer, and does A/V sync.
If it doesn't answer your question let me know because I wrote both (and part of the web audio spec, and part of the webcodecs spec).