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HTTP Live Streaming: IETF draft from Apple

From: RaphaŽl Troncy <Raphael.Troncy@cwi.nl>
Date: Thu, 27 Aug 2009 13:37:30 +0200
Message-ID: <4A966FFA.3090208@cwi.nl>
To: Media Fragment <public-media-fragment@w3.org>
CC: Michael Hausenblas <michael.hausenblas@deri.org>, Dave Singer <singer@apple.com>
Dear all,

Tracker, this is somehow related to the ACTION-95.

I came across the IETF draft "HTTP Live Streaming" from Apple a while 
ago but this is just recently I took the time to investigate further. 
The latest version of the specification is available at [1] while the 
first announcement has been made at [2]. You can also read the RWW 
coverage at [3].

This spec describes a protocol for transmitting unbounded streams of 
multimedia data over HTTP. More precisely, it proposes an extension of 
M3U Playlist files. Media assets are identified by URI and can be of 
type video (and not only audio). These URIs are *segment* of a single 
contiguous media stream. This spec seems to have been originally 
developed for streaming media on your iPhone (thus the relation with 
ACTION-95).

Question(s) 1: Dave, are you familiar with this draft? Do you think the 
media URI in this playlist format could also be media fragment URI?

It seems that nearly one year ago, Microsoft proposed an approach for 
adaptive video streaming over HTTP named Smooth Streaming but that they 
didn't submit this technology standard to IETF to make it RFC. Apple's 
submission seems to be similar, though the spec proposes to extend M3U 
while Microsoft's proposal was based on SMIL. To learn more about the 
Live Smooth Streaming for IIS 7.0, see [4,5]. The blog post [6] is also 
worth to read.

The general idea is that IIS Smooth Streaming extension just maps URL to 
a chunk in a file. So, when receiving a request for the following URI:
http://test.ru/mov.ism/QualityLevels(400000)/Fragments(video=61024)
the IIS Smooth Streaming extension checks "mov.ism" manifest file to 
find filename of the file with requested quality level (400000), opens 
and parses this file to get the chunk with requested time offset 
(61024). Then this chunk is returned in a normal HTTP response.

I have no idea of how often the IIS Smooth Streaming extension is used 
and deployed and whether "fragments" are actually requested this way.

Question 2: Should we ask Microsoft or do you think it will be the kind 
of information the company is not willing to provide publicly?

Cheers.

   RaphaŽl

[1] http://tools.ietf.org/html/draft-pantos-http-live-streaming-01
[2] http://lists.w3.org/Archives/Public/ietf-http-wg/2009AprJun/0237.html
[3] 
http://www.readwriteweb.com/archives/apple_submits_new_spec_for_live_streaming_to_ietf.php
[4] http://www.iis.net/extensions/SmoothStreaming
[5] 
http://learn.iis.net/page.aspx/620/live-smooth-streaming-for-iis-70---getting-started/
[6] 
http://sharovatov.wordpress.com/2009/04/28/silverlight-smooth-streaming-and-http/

-- 
RaphaŽl Troncy
EURECOM, Multimedia Communications Department
2229, route des CrÍtes, 06560 Sophia Antipolis, France.
e-mail: raphael.troncy@eurecom.fr & raphael.troncy@gmail.com
Tel: +33 (0)4 - 9300 8242
Fax: +33 (0)4 - 9000 8200
Web: http://www.cwi.nl/~troncy/
Received on Thursday, 27 August 2009 11:38:27 GMT

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