Jonathan Lennox wrote: > http://www.ietf.org/internet-drafts/draft-lennox-avt-rtp-audio-level-ext > hdr-00.txt > > The draft addresses a similar, though not identical, issue, to > draft-ivov-avt-slic-00. > > It defines an RTP extension header which indicates the audio level, and > voice activity detection state, of a packet's RTP audio payload. In > large conferences, this can reduce the load on an audio mixer or other > middlebox which wants to forward only a few of the loudest audio > streams, without requiring it to decode and measure every stream it's > receiving. I may have not given enough thought to all the side issues, but it seems to me that the two drafts deal with the very same kind of information (and thus its encoding should be specified in only one place). To me, the main issue with passing the sound level of a non-mixed stream has to do with the fact that the RTP header is not going to be encrypted when using SRTP: an in-line attacker could mute a conference participant just mangling such value or, if the header is integrity protected, dropping those packets where voice activity is reported. -- Ciao, Enrico
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