Re: [MMUSIC] Draft new version: t140-data-channel-usage-03 - section 4.2.1
Paul Kyzivat <pkyzivat@alum.mit.edu> Wed, 18 September 2019 16:48 UTC
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To: Christer Holmberg <christer.holmberg@ericsson.com>, "mmusic@ietf.org" <mmusic@ietf.org>
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From: Paul Kyzivat <pkyzivat@alum.mit.edu>
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Date: Wed, 18 Sep 2019 12:48:51 -0400
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Subject: Re: [MMUSIC] Draft new version: t140-data-channel-usage-03 - section 4.2.1
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On 9/18/19 12:29 PM, Christer Holmberg wrote: > Hi, > > * Section 4.2.1: > >>>>>> This section is a little hard to follow. The use of fmtp with data channels is complicated, since the value part of fmtp is dependent on >>>>>> the fmt in the m= line. You do reference RFC4103, but it is still a leap to put this all together. >>>>>> >>>>> I suggest you first discuss the general use of fmtp with data channels - that the value syntax of fmtp is to follow RFC4103. >>>>> >>>>> *Then* you can move on to discuss the use of 'cps'. >>>>> >>>>> It isn't clear to me if there are any other meaningful or permitted fmtp parameters. I suggest you make a definitive statement about this. >>>> >>>> Ok, I can have a look at that. >>> >>> I had a look at this. >>> >>> First, a general description of fmtp with data channels belong to SDPNEG. >> >> I don't think so. The syntax of the value to use with a=fmtp depends on the <fmt> parameter of the m= line. (In the case of RTP this is the >> codec.) When used with a data channel we can't refer to that. Instead, it needs to be determined based on the subprotocol from the dcmap. > > Ok, I thought you wanted text about fmtp usage with data channels in general, regardless of the subprotocol. OK >> And I don't think there is necessarily a consistent mapping for all subprotocols. So I think each subprotocol needs to specify where to go for the syntax of fmtp. > > The draft does that, for T.140 data channels, and in the pull request I clarified that no other usage of fmtp is defined for T.140 data channels. What else is needed? I didn't notice that. But that should cover it. Thanks, Paul
- Re: [MMUSIC] Draft new version: t140-data-channel… Christer Holmberg
- Re: [MMUSIC] Draft new version: t140-data-channel… Paul Kyzivat