[whatwg] I have feature requests for <video> and <audio> tags.

[crocket]

1) <video> and <audio> tags need volume attribute.

I know that it's possible to manipulate the volume attribute with
javascript.
But many internet forums allow some HTML tags but prohibit javascripts.

If I was able to set the initial volume with volume attribute of <video>
and <audio> tags, I would be able to set the initial volume without
javascript.

2) <video> tag needs subtitle attribute.

Without a subtitle attribute, people need to reencode videos with subtitles
to present the videos with subtitles on the web.
I think charset attribute for manually specifying subtitle's character set
would come in handy also.