Re: [Uri-review] In WG last call review of URI Schemes rtsp, rtsps and rtspu

Julian Reschke <julian.reschke@gmx.de> Tue, 08 May 2012 12:14 UTC

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Date: Tue, 08 May 2012 14:14:32 +0200
From: Julian Reschke <julian.reschke@gmx.de>
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To: Magnus Westerlund <magnus.westerlund@ericsson.com>
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Cc: Ted Hardie <ted.ietf@gmail.com>, "mmusic-chairs@tools.ietf.org" <mmusic-chairs@tools.ietf.org>, "uri-review@ietf.org" <uri-review@ietf.org>
Subject: Re: [Uri-review] In WG last call review of URI Schemes rtsp, rtsps and rtspu
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On 2012-05-08 13:48, Magnus Westerlund wrote:
> On 2012-05-08 12:15, Julian Reschke wrote:
>> On 2012-05-08 11:45, Magnus Westerlund wrote:
>>> Larry,
>>>
>>> Can you please clarify something for me. What I have done is that I have
>>> made it clear in the URI syntax that the fragment ABNF construct from
>>> RFC 3986 MAY occur in an valid rtsp URI syntax. Are you saying that this
>>> is not the right thing to do? How could I then indicate the appropriate
>>
>> It's pointless, as a URI scheme definition can't override RFC 3986, and
>> parsing of scheme name and fragment are already defined by RFC 3986.
>>
>> Optimally, a new scheme definition just defines the scheme-specific part.
>>
>>> syntax  when the fragment identifier occur with the URI scheme being
>>> defined? Can't I even say that fragments is not allowed for a scheme?
>>
>> No.
>>
>>> This appear to be the case if one would implicitly define the fragment
>>> in an URI scheme.
>>
>> Exactly :-)
>>
>
> But, then what I have done isn't wrong either as I haven't override the
> rules for fragment, only made it clear how they interface with the URI
> definition. From my perspective I can remove the fragment syntax
> definition, but I would instead at least explicitly call out that
> fragments may occur following RFC 3986 syntax. Personally I don't see
> that as being better.

+0.5.

I agree that what the spec does isn't wrong; it's just a bit misleading 
in that it implies that a URI scheme definition has *any* authority over 
the fragment identifier.

> Secondly, when we are on this topic. Can someone answer how you
> determine the media type for an rtsp URI? RTSP URI points to resources
> that can provide controlled playback of the resource using any number of
> media types in form of RTP payloads formats depending on what is
> suitable for the resource. In fact from issuing an PLAY request on an
> audio only resource you still can receive a media stream where the
> format it is encoded my actually change during the playback operation.
>
> To be clear I don't plan to define a fragment handling format for RTSP
> URIs, but there has been discussion in the past the desire has been to
> do something that is media format agnostic. The goal has been to have an
> uri where you basically say: Play this resource from 5 min 10 seconds
> until 9 min 37 seconds. The proposal is in this 2005 draft.
> http://tools.ietf.org/html/draft-pfeiffer-temporal-fragments-03
>
> But, if the above really isn't possible the question of fragments for
> RTSP is really mote and is just a waste of time to discuss.
> ...

As Larry just mentioned: <http://www.w3.org/TR/media-frags/>

Best regards, Julian