Re: [AVTCORE] WG last call on draft-ietf-avtcore-avp-codecs-01
"Somogyi, Gabor (NSN - HU/Budapest)" <gabor.somogyi@nsn.com> Wed, 20 March 2013 14:07 UTC
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From: "Somogyi, Gabor (NSN - HU/Budapest)" <gabor.somogyi@nsn.com>
To: "DRAGE, Keith (Keith)" <keith.drage@alcatel-lucent.com>, Colin Perkins <csp@csperkins.org>, IETF AVTCore WG <avt@ietf.org>
Thread-Topic: [AVTCORE] WG last call on draft-ietf-avtcore-avp-codecs-01
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Date: Wed, 20 Mar 2013 14:06:25 +0000
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Cc: Magnus Westerlund <magnus.westerlund@ericsson.com>
Subject: Re: [AVTCORE] WG last call on draft-ietf-avtcore-avp-codecs-01
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RFC 1890 (obsoleted by 3551): Audio applications operating under this profile should, at minimum, be able to send and receive payload types 0 (PCMU) and 5 (DVI4). Maybe I am a little bit late, as RFC 1890 was finalized in 1996. Still, my question is why PCMU should be supported, while PCMA is absolutely optional? As far as I know in traditional telecom networks G.711 u-Law (PCMU) is used in North America and Japan only, while A-law is used by the vast majority. And when interconnecting A-law and u-Law regions, then A-Law is used. That suggests that supporting PCMA is at least as important as PCMU. Maybe I answered my own question referring to "traditional telecom networks". I have no access to VoIP / IMS statistics. What is the usage ratio between PCMU and PCMA nowadays? And do you see any firm trend in royalty and patent free codec usage, such as Opus? I am just asking, because if you plan decades ahead, then writing that a high bandwidth but low quality G.711 SHOULD be supported sounds a bit like living in the 20th century. Well, actually in the pre-1980 era, as on radio networks, such as GSM, at least the bandwidth was optimized. And "modern" wireless devices, such as 3GPP LTE clients may not support PCMA/PCMU at all, even though this RFC draft applies to them. (See 3GPP TS 26.114 section 5.2 "Codecs for MTSI clients in terminals".) All in all, I may say that supporting PCMU or PCMA is RECOMMENDED, but definitely remove SHOULD. BR, Gabor Somogyi -----Original Message----- From: avt-bounces@ietf.org [mailto:avt-bounces@ietf.org] On Behalf Of ext DRAGE, Keith (Keith) Sent: Tuesday, March 19, 2013 6:15 PM To: Colin Perkins Cc: Magnus Westerlund; IETF AVTCore WG Subject: Re: [AVTCORE] WG last call on draft-ietf-avtcore-avp-codecs-01 I'm still confused. Surely PCMU0 was recommended before this update and is recommended now. DVI4 was recommended before this update and is now optional. I guess the result of that is that I can be conformant but implement neither, although it will not be a terribly useful implementation. Regards Keith > -----Original Message----- > From: Colin Perkins [mailto:csp@csperkins.org] > Sent: 15 March 2013 18:00 > To: DRAGE, Keith (Keith) > Cc: Magnus Westerlund; IETF AVTCore WG > Subject: Re: [AVTCORE] WG last call on draft-ietf-avtcore-avp-codecs-01 > > On 12 Mar 2013, at 16:40, DRAGE, Keith (Keith) wrote: > > I'm trying to parse the final sentence of the change made to RFC 3551. > > > > Essentially this i-d modifies: > > > > " Audio applications operating under this profile SHOULD, at a minimum, > > be able to send and/or receive payload types 0 (PCMU) and 5 (DVI4). > > This allows interoperability without format negotiation and ensures > > successful negotiation with a conference control protocol." > > > > To become: > > > > " Audio applications operating under this profile SHOULD, at a minimum, > > be able to send and/or receive payload type 0 (PCMU). > > This allows interoperability without format negotiation and ensures > > successful negotiation with a conference control protocol. Some > > environments MAY make support for PCMU mandatory." > > > > What the final sentence currently says is that some environments provide > an option to make support for PCMU mandatory, which implies that other > environments do not provide such an option. Neither of those make sense to > me and there I believe that cannot be the meaning. > > > > I suspect we are looking for sentence that looks more like "Some > environments REQUIRE support for PCMU", but I am not sure if there is an > "only" floating around in there somewhere. > > > I don't think the draft ought to say "only". This sentence looks to be > addressing the RTCWeb use case, which makes PCMU mandatory to implement > but also allows other codecs. > > To my reading, "Some environments MAY make support for PCMU mandatory" and > "Some environments REQUIRE support for PCMU" are equivalent, but I have no > objection to the change if you think it clearer. > > -- > Colin Perkins > http://csperkins.org/ > > _______________________________________________ Audio/Video Transport Core Maintenance avt@ietf.org https://www.ietf.org/mailman/listinfo/avt
- [AVTCORE] WG last call on draft-ietf-avtcore-avp-… Magnus Westerlund
- Re: [AVTCORE] WG last call on draft-ietf-avtcore-… DRAGE, Keith (Keith)
- Re: [AVTCORE] WG last call on draft-ietf-avtcore-… Colin Perkins
- Re: [AVTCORE] WG last call on draft-ietf-avtcore-… Colin Perkins
- Re: [AVTCORE] WG last call on draft-ietf-avtcore-… DRAGE, Keith (Keith)
- Re: [AVTCORE] WG last call on draft-ietf-avtcore-… Somogyi, Gabor (NSN - HU/Budapest)
- Re: [AVTCORE] WG last call on draft-ietf-avtcore-… Ali C. Begen (abegen)
- Re: [AVTCORE] WG last call on draft-ietf-avtcore-… Somogyi, Gabor (NSN - HU/Budapest)
- Re: [AVTCORE] WG last call on draft-ietf-avtcore-… Magnus Westerlund
- Re: [AVTCORE] WG last call on draft-ietf-avtcore-… Magnus Westerlund
- Re: [AVTCORE] WG last call on draft-ietf-avtcore-… Timothy B. Terriberry