Re: [MMUSIC] Open Issues: draft-ietf-mmusic-sdp-simulcast-03

Martin Thomson <martin.thomson@gmail.com> Sat, 24 October 2015 15:32 UTC

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Date: Sat, 24 Oct 2015 08:32:16 -0700
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From: Martin Thomson <martin.thomson@gmail.com>
To: Paul Kyzivat <pkyzivat@alum.mit.edu>
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Subject: Re: [MMUSIC] Open Issues: draft-ietf-mmusic-sdp-simulcast-03
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On 23 October 2015 at 11:10, Martin Thomson <martin.thomson@gmail.com> wrote:
> On 23 October 2015 at 11:00, Paul Kyzivat <pkyzivat@alum.mit.edu> wrote:
>> But I'm not loving "!" - it is hard to distinguish from "1". Of course this
>> isn't a problem for parsers, only for us humans reading examples and traces.
>> I would prefer some other character, perhaps "-", "~" or "/".
>
>
> As I said, I'm not partial to it.  It was selected on the basis that
> it was the first valid choice.  I have no problem with "~" or "/",
> though "-" is a valid rid identifier character.


Alternative:

simulcast-rid-args = simulcast-rid-option *(";" simulcast-rid-option)
simulcast-rid-option = simulcast-rid-list [ "/" simulcast-rid-list ]
simulcast-rid-list = rid-identifier *("," rid-identifier)

Where everything after a slash is paused, e.g.,

a=simulcast:send rid=1,2,3/4,5;1,2/3,4,5

Noting that this makes the set of paused streams selectable.  The
original grammar did not.  I don't know if that makes sense.  If not,
then:

simulcast-rid-args = simulcast-rid-list *(";" simulcast-rid-list)
                               ["/" simulcast-rid-list]
simulcast-rid-list = rid-identifier *("," rid-identifier)

Which is simpler, e.g.,

a=simulcast:send rid=1,2,3;1,2/4,5