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

Rodger Combs rodger.combs at gmail.com
Tue Feb 21 16:06:18 PST 2012

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.

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