Media Source draft proposal

In December, the Media Pipeline Task Force of the Web & TV Interest Group
sent a note to
the HTML WG that included a link to three different architectural options
for supporting
Adaptive Streaming in HTML5 applications:
http://lists.w3.org/Archives/Public/public-html/2011Dec/0120.html
http://www.w3.org/2011/webtv/wiki/MPTF/ADR_Error_Codes#Architectural_Models

One model proposes to allow "script to explicitly send the media segments.
The manifest
file is processed by script and any adaptation algorithm can be used to
select the
individual segments for playback."

Together, Google, Netflix, and Microsoft have developed a concrete proposal
that supports
this scenario. We have updated the proposal in recent weeks based on
feedback from the
Web & TV IG and would like to submit the document for consideration by the
HTML Working
Group.

We have uploaded the draft "Media Source" proposal here:
http://dvcs.w3.org/hg/html-media/raw-file/tip/media-source/media-source.html

This document is intended to be a starting point for discussion. We have
highlighted
several open issues in the document and there are no doubt other issues.
The goal of the
extension specification is to provide additional functionality to HTML5
media elements
so that web pages can programmatically feed data into different media
tracks. One use
of this feature is to support the adaptive streaming scenario outlined by
the interest
group but it isn't the only one. Other scenarios include offline video
editing (media
could be read with File API and local processing done on source data),
seamless playlists,
and fast "TV-like" channel switching (you don’t need to resend init
segments on changes).

With the group's agreement, we would like to discuss this proposal in the
working group
as part of the HTML.next conversation started last year:
http://www.w3.org/wiki/HTML/next#Adaptive_Streaming

Specifically, we think it would be useful for the proposed Media Task Force
to consider
this proposal alongside the Encrypted Media proposal. We believe that both
specifications
are useful independently and one can be usefully implemented without the
other. However,
since they both extend the HTML5 media elements, it is useful for them to
be considered in
the same forum to ensure they do not conflict.

Aaron Colwell, Google
Adrian Bateman, Microsoft
Mark Watson, Netflix