[whatwg] Bandwidth media queries

[James Graham]

On Wed, 16 May 2012, Matthew Wilcox wrote:

> First off I know that a number of people say this is not possible. I
> am not wanting to argue this because I don't have the knowledge to
> argue it - but I do want to understand why, and currently I do not.
> Please also remember that I can only see this from an authors
> perspective as I'm ignorant of the mechanics of how these things work
> internally.
>
> The idea is to have something like:
>
> <link media="min-bandwidth:0.5mps" ... />
> <link media="min-bandwidth:1mps" ... />
> <link media="min-bandwidth:8mps" ... />

Without going deeper into the specific points, implementation experience 
suggests that even implementing a binary low-bandwidth/high bandwidth 
detection is extremely difficult; Opera has one coupled to the UI for the 
"turbo" feature and it has been somewhat non-trivial to get acceptable 
quality.

In general the problem with trying to measure something like bandwidth is 
that it is highly time-variable; it depends on a huge number of 
environmental factors like the other users/applications on the same 
connection, possible browser features like down-prioritising connections 
in background tabs, external environmental features like "the train just 
went into a tunnel" or "I just went out of range of WiFi and switched to 
3G" and any number of other things. Some of those are temporary 
conditions, some are rapid changes to a new long-term state. Trying to 
present a single number representing this complexity in realtime just 
isn't going to work.