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Re: Relevant Protocols for Media Fragments

From: RaphaŽl Troncy <Raphael.Troncy@cwi.nl>
Date: Wed, 11 Feb 2009 10:58:52 +0100
Message-ID: <4992A15C.3010602@cwi.nl>
To: Davy Van Deursen <davy.vandeursen@ugent.be>
CC: "'Media Fragment'" <public-media-fragment@w3.org>, "'Silvia Pfeiffer'" <silviapfeiffer1@gmail.com>

Dear Davy,

> Although MMS is specified as protocol in the URL, this doesn't mean that the
> media will be delivered through the MMS protocol. Microsoft has deprecated
> the MMS protocol in favor of RTSP in 2003 (release of Windows Media 9
> Series), as pointed out by Silvia. The confusing thing is that, although
> Microsoft stopped supporting the MMS protocol, they still recommend using
> 'mms://' as "protocol rollover". Cited from [1]: "When a URL specifies
> 'mms://', the reader attempts to use the following protocols for data
> delivery, in the following order:
>    1. RTSPU (RTSP using UDP)
>    2. RTSPT (RTSP using TCP)
>    3. MMSU (MMS using UDP)
>    4. MMST (MMS using TCP)
>    5. HTTP".
> Another interesting statement in [1] is as follows: "Windows Media Services
> 9 Series in Microsoft Windows Server 2003 will reject any MMSU or MMST
> requests from a Windows Media Format SDK reader, because RTSP is the
> preferred streaming protocol. Windows Media Services version 4.1 and earlier
> do not support RTSP. In this case the reader object falls back to MMSU or
> HTTP."
> Hence, I tested which protocol is really behind
> mms://oxy.ijs.si/2008/active/iswc08_karlsruhe/troncy_biptc/iswc08_troncy_bip
> tc_01.wmv, and it turned out to be RTSPT (i.e., RTSP using TCP). Note that
> also
> rtsp://oxy.ijs.si/2008/active/iswc08_karlsruhe/troncy_biptc/iswc08_troncy_bi
> ptc_01.wmv works in Windows Media Player. Therefore, I guess that in most of
> the 'mms://' URLs, RTSP is used as underlying delivery protocol.

Wahouuu! This is a very interesting finding! You make my day :-)
And microsoft folks are really putting traps everywhere, now I can even 
not trust the URI syntax :-)
Thanks for this investigation.


RaphaŽl Troncy
CWI (Centre for Mathematics and Computer Science),
Science Park 123, 1098 XG Amsterdam, The Netherlands
e-mail: raphael.troncy@cwi.nl & raphael.troncy@gmail.com
Tel: +31 (0)20 - 592 4093
Fax: +31 (0)20 - 592 4312
Web: http://www.cwi.nl/~troncy/
Received on Wednesday, 11 February 2009 09:59:37 UTC

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