Re: [MMUSIC] Issue #27: Allow RTP attributes in non-media m= sections

Taylor Brandstetter <deadbeef@google.com> Thu, 16 February 2017 19:11 UTC

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From: Taylor Brandstetter <deadbeef@google.com>
Date: Thu, 16 Feb 2017 11:11:40 -0800
Message-ID: <CAK35n0ahmN7qPW2H-yNrqoP1tOaHwJCjrDy+VZ+cCwi_reXX0Q@mail.gmail.com>
To: Christer Holmberg <christer.holmberg@ericsson.com>
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Subject: Re: [MMUSIC] Issue #27: Allow RTP attributes in non-media m= sections
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>
> Yes, I meant "not" :)


I can't find this restriction in the current draft of BUNDLE. Also, this
restriction would make BUNDLE even more complex and non-future-proof
(suppose some future protocol that can be bundled with RTP also has its own
TRANSPORT attributes). What are the reasons for this restriction? Shouldn't
endpoints ignore attributes they don't expect? "If an attribute is received
that is not understood, it MUST be ignored by the receiver."


> OR, we change the mux category for the RTP-specific parameters. But, that
> of course means they have to be added to every RTP m= section.
>

That wouldn't make sense in my opinion. If rtcp-rsize wasn't a
transport-level attribute, then multiple bundled m= sections would be
allowed to use different values for it. It's fundamentally a
transport-level attribute.


On Thu, Feb 16, 2017 at 10:07 AM, Christer Holmberg <
christer.holmberg@ericsson.com> wrote:

> Yes, I meant "not" :)
>
> Sent from my iPhone
>
> On 16 Feb 2017, at 18.59, Eric Rescorla <ekr@rtfm.com> wrote:
>
>
>
> On Thu, Feb 16, 2017 at 9:07 AM, Christer Holmberg <
> christer.holmberg@ericsson.com> wrote:
>
>> Hi,
>>
>>
>>
>> *>*See:
>>
>> >https://github.com/cdh4u/draft-sdp-bundle/issues/27
>>
>> >https://github.com/rtcweb-wg/jsep/issues/528
>>
>> >
>>
>> >The basic issue is that it's possible to have a situation where you have
>> both
>>
>> >media and data m= sections but the BUNDLE tag is associated with the data
>>
>> >m= section and now you need to put the TRANSPORT and IDENTICAL
>>
>> >attributes somewhere. The JSEP editors discussed this and came to the
>>
>> >conclusion that it should go with the BUNDLE tag (i.e., in the data m=
>> section)
>>
>> >and that BUNDLE should forbid this, but it requires a change to BUNDLE.
>>
>>
>>
>> Did you mean to say that BUNDLE should NOT forbid this?
>>
>>
>>
>> Based on your GitHub discussion, my understanding is that you want to
>> allow to include RTP-specific parameters (‘rtcp-mux’, ‘rtcp’,
>> ‘rtcp-mux-only’ attributes etc) in the data m= section.
>>
>
> Yes/
>
>
>>
>>
>> To repeat what I said on GitHub:
>>
>>
>>
>> This has been discussed in the past, and the outcome has been to now
>> allow RTP-specific parameters in non-RTP m= sections.
>>
>
> Do you mean "not" rather than now?
>
> -Ekr
>
>
>>
>>
>> A solution would be to simply change the bundle tag when the RTP m=
>> sections are added.
>>
>>
>>
>> …OR, we change the mux category for the RTP-specific parameters. But,
>> that of course means they have to be added to every RTP m= section.
>>
>>
>>
>> Regards,
>>
>>
>>
>> Christer
>>
>
>
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