RE: [Sipping] Use cases of multi-transcoding
"Henry Sinnreich" <henry@pulver.com> Tue, 21 February 2006 09:34 UTC
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From: Henry Sinnreich <henry@pulver.com>
To: Albrecht.Schwarz@alcatel.de, 'Kang Tae-Gyu' <tgkang@etri.re.kr>
Subject: RE: [Sipping] Use cases of multi-transcoding
Date: Tue, 21 Feb 2006 10:34:32 +0100
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> Transcoding as such should be avoided because it is inherently decreasing > the audio/speech quality Correct! > Comments? The numerous wireline legacy ITU-T G.7xx codecs and other countless codecs deployed for mobile phones are a disgrace IMHO. The industry would be better off adopting "Internet codecs": The iLBC RFC 3951 and RFC 3952 as the default codec and SPEEX for variable rate wideband (ftp://ftp.rfc-editor.org/in-notes/internet-drafts/draft-ietf-avt-rtp-speex- 00.txt). Thanks, Henry -----Original Message----- From: Albrecht.Schwarz@alcatel.de [mailto:Albrecht.Schwarz@alcatel.de] Sent: Tuesday, February 21, 2006 8:29 AM To: Kang Tae-Gyu Cc: sipping@ietf.org Subject: Re: [Sipping] Use cases of multi-transcoding Hi Kang, just a comment to the transcoding scenario between two different WB codecs (WB1<->WB2). Transcoding as such should be avoided because it is inherently decreasing the audio/speech quality ("adds e.g., delay impairments and Ie, equipment impairment factors") and an "expensive" network function. There must be therefore an agreed justifaction, particularly for WB1<->WB2 transcoding scenarios! Transcoding between two different NB codecs (NB1<->NB2) is often inevitable. The difference with WB codecs is that terminals "should support a fallback mode to a NB codec" in my opinion. There are two possibilities: NB mode is part of the WB codec modes of operation (e.g., G.729EV with G.729A as NB mode), or separate NB codec (e.g., terminal concept according G.725). The inconsistent "WB1<->WB2" E2E scenario might then lead to fallbacks to (default) NB codecs. In case of a then "NB1<->NB2" inconsistency to NB transcoding in the network. Comments? Albrecht "Kang Tae-Gyu" <tgkang@etri.re. To: <sipping@ietf.org> kr> cc: xupeili@huawei.com, rohan@ekabal.com, Gonzalo.Camarillo@ericsson.com, dean.willis@softarmor.com 21.02.2006 03:12 Subject: [Sipping] Use cases of multi-transcoding Please respond to Kang Tae-Gyu Hello, I would like to discuss about the use case of multi-transcoding. First of all, I am sorry for that I could not answer about its use case when I received the question from the floor, IETF 64 Vancouver meeting, because of poor English. Also, thank you for the minutes(chairmen and note takers). There are three kinds of use cases of multi-transcoding. - one or two more heterogeneous networks - one or two more ITSPs - one or two more wideband speech codecs There are one or two more heterogeneous networks: enterprise networks using IP-PBX, ITSP(Internet Telephony Service Provider), IMS in 3GPP2, PacketCable, and Wibro. They will not use a common codec. So, they need multi transcoding such as; - use case 1: A(a) - IP PBX T1(a-b) - ITSP T2(b-c, b-d) - IMS T3(a-d, d-e) - D(d) - use case 2: A(a) - IP PBX T1(a-b) - ITSP T2(b-c, b-d) - PacketCable T4(c-d) - F(d) - use case 3: E(e) - IMS T3(a-d, e-d) - ITSP T2(b-c, b-d) - Wibro T4(a-d, d-c) - G(c) There are one or two more ITSPs or SBC because all of internet telephony subscribers will not subscribe only one ITSP. There are a lot of domestic ITSPs and international ITSPs or ITXP. Internet telephony should be supported any kind of terminal vendor even though it supports any specific codec. It also supports multi call forwarding service. So, they need multi transcoding such as; - use case 4: C(c) - ITSP T2(c-b, b-d) - ITSP T6(b-a, b-d) - ITSP7 T7(a-d, d-e) - G(d) There are one or two more wideband speech codecs. There has been developing one or two more wideband speech codecs for internet telephony: AMR-WB in 3GPP, VMR-WB in 3GPP2, G.729EV in ITU-T SG 16 Question 10, a wideband codec in ITU-T SG 16 Question 9, and AAC in ISO/IEC. In this convention, Capital letter means a node and lowercase(a, b, c, d, and e) means a codec. A wideband codec encodes voice using 16,000 samples per second (50 ~ 7,000Hz), as opposed to the 8,000 samples per second (300 ~ 3,400Hz) by narrowband codec. A voice quality of wideband codec is better than one of narrowband codec due to support wider band. A tandem transcoding means to encode narrowband codec such as G.711. So, it makes down sampling and worse the voice quality. If two parties(calling party and called party) have two different wideband codecs, transcoders should transcode a wideband codec to another wideband codec without tandem transcoding. If we use a common codec with G.711(tandem), there is no more need multi-transcoding. But, we need a multi-transcoding for supplying a wideband speech high quality to each sides. - use case 5: wideband codec to wideband codec without tandem transcoding Multi transcoding signaling can be useful for internet telephony environments supported by standard; an example VoIP network in quality of service for next generation Voice over IP networks, MSF-TR-QoS-001.final, 2003 Feb, and Telecommunications and Internet Protocol Harmonization over Networks (TIPHON) Release 3; End-to-End Quality of Service in TIPHON Systems; Part 3: Signalling and Control of End-to-End Quality of Service (QoS)-V2.1.2, 2002. Multi trascoder can cover the use case using one or two more conference bridge transcoding model. We would like to discuss open these use cases or another use case. Comments are welcome. Thanks, Kang _______________________________________________ Sipping mailing list https://www1.ietf.org/mailman/listinfo/sipping This list is for NEW development of the application of SIP Use sip-implementors@cs.columbia.edu for questions on current sip Use sip@ietf.org for new developments of core SIP _______________________________________________ Sipping mailing list https://www1.ietf.org/mailman/listinfo/sipping This list is for NEW development of the application of SIP Use sip-implementors@cs.columbia.edu for questions on current sip Use sip@ietf.org for new developments of core SIP _______________________________________________ Sipping mailing list https://www1.ietf.org/mailman/listinfo/sipping This list is for NEW development of the application of SIP Use sip-implementors@cs.columbia.edu for questions on current sip Use sip@ietf.org for new developments of core SIP
- [Sipping] Use cases of multi-transcoding Kang Tae-Gyu
- Re: [Sipping] Use cases of multi-transcoding Albrecht.Schwarz
- RE: [Sipping] Use cases of multi-transcoding Henry Sinnreich
- RE: [Sipping] Use cases of multi-transcoding Nathan Allen Stratton
- RE: Re: [Sipping] Use cases of multi-transcoding Kang Tae-Gyu
- RE: [Sipping] Use cases of multi-transcoding LAI, SHOU WEN -HCHBJ
- RE: [Sipping] Use cases of multi-transcoding Kang Tae-Gyu
- RE: [Sipping] Use cases of multi-transcoding Kang Tae-Gyu
- RE: [Sipping] Use cases of multi-transcoding Henry Sinnreich
- RE: [Sipping] Use cases of multi-transcoding Roy, Radhika R.
- RE: [Sipping] Use cases of multi-transcoding Drage, Keith (Keith)
- RE: [Sipping] Use cases of multi-transcoding Brian Rosen
- RE: [Sipping] Use cases of multi-transcoding Henry Sinnreich
- Re: [Sipping] Use cases of multi-transcoding Tom-PT Taylor
- RE: [Sipping] Use cases of multi-transcoding Michael Hammer (mhammer)
- Re: [Sipping] Use cases of multi-transcoding Stephen Sprunk
- RE: [Sipping] Use cases of multi-transcoding Kang Tae-Gyu
- RE: [Sipping] Use cases of multi-transcoding Roy, Radhika R.
- RE: [Sipping] Use cases of multi-transcoding Burger, Eric