logistical programming question (youtube)

I was browsing youtube a bit earlier, watching some Eddie Izzard clips (yay!), and some of them were very quiet, so I turned up the volume of my speakers. Of course, when I switched to another clip, I suddenly discovered that Eddie was in fact sitting next to me screaming into my ear. I wondered what Senor Izzard had against my eardrums until I realized that it was in fact youtube that was culpable.

Now I recognize that clips are uploaded to youtube from millions of discrete sources, and there’s no way to police them manually, but it got me to thinking: Is there some way to program something that checks the decibel levels so that it won’t output more than a certain level? I know there’s something like this for TV, so I can’t imagine it would be all that difficult. However, since my programming knowledge consisted of one (1) HS class of javascript (scripto del java), I thought I’d turn to the Dope for some answers.

Can this be done, and if so, why wouldn’t youtube have implemented it?

Yes, it’s would be quite easily possible for them to normalise the sound level. I don’t know why they haven’t done it - they presumably perform other kinds of processing on the uploaded files.