[whatwg] Video source selection based on quality

timeless timeless at gmail.com
Wed Mar 10 01:25:21 PST 2010

David Singer wrote:
> I am by no means convinced that automatic selection of sources other
> than that based on the most obvious, automated, criteria, is wise or
> needed.  We have had for many years, in QuickTime, this facility, and
> quite a few sites opted not to use it and allow the user a manual
> choice instead.

On Fri, Feb 19, 2010 at 4:31 PM, Mikko Rantalainen
<mikko.rantalainen at peda.net> wrote:
> Was it ever investigated *why* they opted not to use it? Perhaps the
> automatic selection was somehow incorrectly implemented instead of being
> just a bad idea?

I think David correctly articulated one of the reasons. A user might
be willing to wait for a trailer to download to see it with a better
resolution. I know that 15 years ago when I was watching trailers
(RealPlayer or QuickTime), I would often choose to wait. But it
depended on constraints that my useragent was entirely unable to

* Was I preparing to show a bunch of friends on a big screen?
* Was I in a hurry, such that I just wanted to see a quick preview?

> These are two different use cases and preferably the user is able to
> inform their UA which one they prefer.

Trying to explain this in a selection box is hard. Go look at how
movie trailers were offered to users 15 years ago (I can't speak to
recent times, I've sadly grown up and now watch most of my trailers in
Theaters while wishing I had remembered to buy popcorn). The choices
were typically fairly large images with pretty content and descriptive
text. They weren't simply a drop down with plain, boring, flat icons.

Personally, I've recently tried to use YouTube's player and was
totally thrown by the 360/480/720 stuff. I expected it to
automatically change the onscreen video size, but it didn't. So I
eventually learned that I wanted to use the full screen button after
upgrading. I'd like to say that I still don't understand why.

> Most of the time I'd rather get a
> streaming movie unless I specifically know that I want the best quality
> no matter how long I have to wait (the latter case being a special case).

Well. I just spent Sunday night at a friend's and I complained about
his video collection. He had some movies, I don't want to speculate
about how he got them. Since he presumably acquired them while he
wasn't in a hurry, and he presumably isn't starved for space, I'd have
much preferred that he got a better quality movie so that we could
more properly enjoy the movie on his large screen.

> I'd suggest two somewhat simple parameters for a movie to describe the
> quality: actual average bitrate and virtual average MPEG2 bitrate. I'll
> explain these below.

This sounds way too complicated for end users. We prefer to be ignorant.

> UA shouldn't automatically select a movie for
> streaming that has higher average bitrate than the current data
> connection can transfer.

This is problematic. Traffic shaping and Burst support is afaiu common
in the US. Plus with cable modems and shared links, your available
bandwidth fluctuates.

What RealPlayer/QuickTime/Windows Media Player did classically was let
me, the user, indicate what kind of line I was on, so that in theory
it could select the most appropriate content format. I'm not sure it
ever worked. I was typically on dialup or in a university. But my
computer (not a laptop) traveled with me between these locations, so I
had to remember to fix the setting....

The rest of your text is *way* too complicated for the average user.

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