Re: [codec] WG Review: Internet Wideband Audio Codec (codec)

[Daniel Petrie <[e-mail]>]

While we are discussing conferencing, I would like to add my wish list of requirements:

I would want the following information included in the RTP packet so that I can do speaker selection on the streams without having to have the expense of decoding them and run the algorithms to calculate these values.  This is useful in all 3 of Christian's conferencing scenarios.

1) Voice activity indication (minimally binary, ideally magnitude)
2) gain control either already applied or a multiplier to apply to achieve a consistent gain.
3) Energy level

--- On Wed, 1/13/10, Christian Hoene <[e-mail]> wrote:

> From: Christian Hoene <[e-mail]>
> Subject: Re: [codec] WG Review: Internet Wideband Audio Codec (codec)
> To: "'Alexander Chemeris'" <[e-mail]>
> Cc: [e-mail]
> Date: Wednesday, January 13, 2010, 5:55 AM
> > This codec should be also useful
> in
> > conference
> > scenarios, where you have to decode it at conference
> server and encode
> > mixed signal again. And if I haven't missed something,
> this use-case
> > was
> > explicitly listed in codec requirements.
> 
> The conferencing scenario is not yet well described in the
> current codec requirements document. Different kinds of
> systems are possible:
> 
> 1) A central conferencing server that serves all clients.
> - a) which does a efficient single changing mixing - still
> a challenge if you have multiple operational modes in a
> codec.
> - b) which does a more intelligent mixing using (at least)
> two channels to support spatial hearing - this increases the
> quality of conference call significant. Thus, stereo modes
> must be supported if the codec shall support state of the
> art conferencing technologies.
> 2) A mesh-like N-to-N transmission conference call. Then
> you might benefit from layered coding because you have at a
> client you have to encode only once. But then again, how to
> support multiple coding modes?
> 3) One client acts as conference server (similar to 1)
> 
> In total, the support of conferencing calls will require:
> - Layered coding
> - Efficient mixing of streams
> - Support of stereo
> - Good (self-)transcoding
> Is this all achievable?
> 
> Christian
> 
> 
> _______________________________________________
> codec mailing list
> [e-mail]
> https://www.ietf.org/mailman/listinfo/codec
>