Re: [AVT] Audio Level Indicators - new versions submitted
Stefan Sayer <stefan.sayer@iptego.com> Thu, 22 October 2009 09:57 UTC
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Date: Thu, 22 Oct 2009 11:57:38 +0200
From: Stefan Sayer <stefan.sayer@iptego.com>
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To: Emil Ivov <emcho@sip-communicator.org>
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Cc: "Audio/Video Transport (AVT) WG" <avt@ietf.org>
Subject: Re: [AVT] Audio Level Indicators - new versions submitted
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Hello, o Emil Ivov [10/22/09 11:25]: > All, > > As requested by the chairs several weeks ago, Jonathan, Enrico and I > have submitted new versions of the client-to-mixer [1] and > mixer-to-client [2] audio level indication drafts. Both documents > reflect comments received on the mailing list such as: > > * using a uniform way of encoding level > * add additional considerations/design choices sections > * change tittles so that they would be easier to distinguish from one > another > * others > > Needless to say further comments are most welcome. in [1] 3. Protocol Operation the levels are described as having values from 0 to 255, and referencing section 4 (which should be section 5): Each instance of this header contains a list of one-octet audio level values (see Section 4). Such values indicate audio level on a 0 to 255 scale where 0 is silence (i.e. same as omitting the corresponding source id from the CSRC list) and 255 corresponds to a threshold accepted by the mixer implementation as the maximum audio level that a participant is likely to reach during a conference. while in section 5, the levels are described like in the comfort noise specification with values 0..127 being 0..-127 dBov, where 0 would be the maximum audio level threshold (not 255). In [2], section 3, the MSB of the level field is in the Figure 1 of the extension block: 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ID | len=1 |0| level |V| reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ So it may make sense to add this to Figure 2 in [1] as well : 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ID | len | level 1 | level 2 | level 3 ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: Audio level indicators extension format would become: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ID | len |0| level 1 |0| level 2 |0| level 3 ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: Audio level indicators extension format (or, alternatively remove it from Figure 1 in [2], but I think that it is good to have the MSB set to 0 in the Figure.) Regards Stefan > > Cheers, > Emil > > [1] - http://tools.ietf.org/html/draft-lennox-avt-rtp-audio-level-exthdr > > [2] - http://tools.ietf.org/html/draft-ivov-avt-slic > _______________________________________________ > Audio/Video Transport Working Group > avt@ietf.org > https://www.ietf.org/mailman/listinfo/avt -- Stefan Sayer VoIP Services stefan.sayer@iptego.com www.iptego.com IPTEGO GmbH Wittenbergplatz 1 10789 Berlin Germany Amtsgericht Charlottenburg, HRB 101010 Geschaeftsfuehrer: Alexander Hoffmann
- [AVT] Audio Level Indicators - new versions submi… Emil Ivov
- Re: [AVT] Audio Level Indicators - new versions s… Stefan Sayer
- Re: [AVT] Audio Level Indicators - new versions s… Stefan Sayer
- Re: [AVT] Audio Level Indicators - new versions s… Enrico Marocco
- Re: [AVT] Audio Level Indicators - new versions s… Enrico Marocco
- Re: [AVT] Audio Level Indicators - new versions s… Emil Ivov
- Re: [AVT] Audio Level Indicators - new versions s… Emil Ivov
- Re: [AVT] Audio Level Indicators - new versions s… Stefan Sayer