[whatwg] <source>s in <video> by quality as well as codec

Ian Hickson ian at hixie.ch
Tue Jun 5 14:54:23 PDT 2012

On Tue, 21 Feb 2012, Rodger Combs wrote:
> I propose that <source> add a quality, bitrate, or filesize attribute to 
> allow the UA to decide between multiple streams by choosing the maximum 
> quality file that it can download within a reasonable amount of time 
> (e.g. it will download faster than it will play) or based on a user 
> preference (e.g. prefer SD quality, or always use HD when provided). It 
> should also be possible to retrieve a list of the <source>s the UA can 
> play in JS, and switch between them by user action (either a JS call for 
> a custom UI or a dropdown in the builtin UI), loading the new file and 
> switching to it with minimal skipping. This way, a site like YouTube, 
> which presents several files in various bitrates and codecs, can allow 
> the user to choose to use a higher quality without having to force an 
> src attribute on the video, and a mobile UA that roams from 3G to WiFi 
> or moves close to a base station can increase the quality of its stream. 
> I think it fits in well with the purpose of the source element. This is 
> certainly open for modification, but I think it's a good concept in 
> essence.

If this is for a site like YouTube, I think an adaptive network channel 
would be a more effective solution (i.e. one where the download adapts in 
real time to changing network conditions, with the endpoints negotiating 
with each other regarding what to transmit).

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'

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