Re: [AVT] Audio Level Indicators - new versions submitted

[Stefan Sayer <stefan.sayer at iptego.com>]

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

Why not use the (so far unused) MSB of the audio level in the
mixer-to-client extension header as voice activity flag (live the V in
client-to-mixer) ?

While it is possible for the mixer, it may be impossible for the client 
to accurately determine voice activity of the participants (e.g. the 
spectral information is lost).

The format would then look like this:
    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  |V|  level 1    |V|  level 2    |V|  level 3   ...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

             Figure 2: Audio level indicators extension format

An open question would be whether this is mandatory, or how a mixer 
could signal that it is not doing voice activity detection (i.e. V will 
be zero all the time).

Stefan

> [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 at ietf.org
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