alt Hacker News..I'm thinking of the <video> <source> elements: https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/...
> If the type attribute is specified, the browser immediately compares it with the media types it can display. If the type is not supported, the browser skips querying the server and directly checks the next <source> element.
Huh. That's interesting but in practice it doesn't quite work. The major streaming platforms want to handle things programmatically in chunks and they need a way to establish what codec (among various other parameters) to use before they get started. So the requirement is a browser mechanism to make that information available to server provided code running on the client. And I'm further stipulating that this mechanism should facilitate optional intervention by the user.