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

Charles Pritchard chuck at jumis.com
Tue Jun 5 15:23:00 PDT 2012

On Jun 5, 2012, at 2:54 PM, Ian Hickson <ian at hixie.ch> wrote:

> 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).

I'd like to see strawman proposals for resource description markup.

Presently, magnet+BitTorrent is the only mature and implemented tech in this field that I've found with wide support. And it's not even meant for adaptive streaming.

I know that markup for subtitles happened in this group. I'd like to see an effort for markup for resources, with the same experimental atmosphere.

The hope being that we can copy and paste some kind of text markup which describes various endpoints and metadata sufficient for streaming strategies for media.


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