IETF Logo Mail Archive

Re: [codec] #14: VAD and CNG?

"Benjamin M. Schwartz" <bmschwar@fas.harvard.edu> Mon, 24 May 2010 16:54 UTC

Return-Path: <bmschwar@fas.harvard.edu>
X-Original-To: codec@core3.amsl.com
Delivered-To: codec@core3.amsl.com
Received: from localhost (localhost [127.0.0.1]) by core3.amsl.com (Postfix) with ESMTP id CBE153A6C63 for <codec@core3.amsl.com>; Mon, 24 May 2010 09:54:23 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -4.37
X-Spam-Level:
X-Spam-Status: No, score=-4.37 tagged_above=-999 required=5 tests=[AWL=-0.371, BAYES_50=0.001, RCVD_IN_DNSWL_MED=-4]
Received: from mail.ietf.org ([64.170.98.32]) by localhost (core3.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id mnX1tlY9-9Fe for <codec@core3.amsl.com>; Mon, 24 May 2010 09:54:22 -0700 (PDT)
Received: from us26.unix.fas.harvard.edu (us26.unix.fas.harvard.edu [140.247.35.202]) by core3.amsl.com (Postfix) with ESMTP id 77F6D3A6C44 for <codec@ietf.org>; Mon, 24 May 2010 09:54:22 -0700 (PDT)
Received: from us26.unix.fas.harvard.edu (localhost.localdomain [127.0.0.1]) by us26.unix.fas.harvard.edu (Postfix) with ESMTP id 855381F7388; Mon, 24 May 2010 12:54:13 -0400 (EDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed; d=fas.harvard.edu; h= message-id:date:from:reply-to:mime-version:to:cc:subject :references:in-reply-to:content-type; s=mail; bh=+8E3nmUjb8nL6To jLoBoOQyrqc0q0yRWOxHbPqrVMjA=; b=vn0c8R2hkIBl7rrNPmNtkyc1CR+864x VZIEl1sj6Ot2yTuchHS//c1L6krtOCYDmD2Mmu9mHb2LJu5lVS3DZyWwpPdQBiXx un+jG8KnyQrRMYAqktoniG9D3fu+ORBo6Nq96F5uw5GlrRwBHGprAddjOgO7wO4a nsjOVCuRTng8=
DomainKey-Signature: a=rsa-sha1; c=simple; d=fas.harvard.edu; h= message-id:date:from:reply-to:mime-version:to:cc:subject :references:in-reply-to:content-type; q=dns; s=mail; b=qvzJ3Js1r wUzm2u3W/W8+gO4xgOP/U2YE74o7s0LWTU6QCElmRSKjgcg5qPnm0LDaeg3wMnVx ae078psamDFy0Kk5Kx5wxFSqHs2YPJJstha0nJSGked6g/Z3wghOu38fGxrp6CM8 ZT5BcVM4GvIhLU59twXEtwkwKIjtoO8OVA=
Received: from [172.23.141.149] (bwhmaincampuspat25.partners.org [170.223.207.25]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: bmschwar@fas) by us26.unix.fas.harvard.edu (Postfix) with ESMTPSA id 807331F7375; Mon, 24 May 2010 12:54:13 -0400 (EDT)
Message-ID: <4BFAAF34.202@fas.harvard.edu>
Date: Mon, 24 May 2010 12:54:12 -0400
From: "Benjamin M. Schwartz" <bmschwar@fas.harvard.edu>
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.9) Gecko/20100423 Thunderbird/3.0.4
MIME-Version: 1.0
To: Michael Knappe <mknappe@juniper.net>
References: <C81FF1F7.16BE0%mknappe@juniper.net>
In-Reply-To: <C81FF1F7.16BE0%mknappe@juniper.net>
X-Enigmail-Version: 1.0.1
Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="------------enig5C2DEF1A4D23CED2D23CD005"
Cc: "codec@ietf.org" <codec@ietf.org>
Subject: Re: [codec] #14: VAD and CNG?
X-BeenThere: codec@ietf.org
X-Mailman-Version: 2.1.9
Precedence: list
Reply-To: bens@alum.mit.edu
List-Id: Codec WG <codec.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/listinfo/codec>, <mailto:codec-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/codec>
List-Post: <mailto:codec@ietf.org>
List-Help: <mailto:codec-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/codec>, <mailto:codec-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 24 May 2010 16:54:23 -0000

On 05/24/2010 12:05 PM, Michael Knappe wrote:
> I agree that VAD (or DTX) needs to be negotiable.

Me too.  Specifically, I think that DTX should always be allowed within
any stream.  The decoder always MUST correctly decode a stream with or
without DTX, and the encoder SHOULD obey the decoder's preference for or
against DTX, as expressed in SDP, unless there is a reason not to obey
this preference.  Decoders MAY express no preference.

In particular, decoders must handle adaptive jitter buffering properly
with or without DTX.

Examples:
An encoder operating with push-to-talk hardware (microphone active only
when a button is depressed) should always use DTX, regardless of decoder
preference.

A decoder that cares about average bandwidth should probably request DTX
enabled, whereas a decoder that cares only about peak bandwidth should
request DTX disabled.

A decoder that cares about non-voice background sounds should request DTX
disabled.

--Ben

v2.23.0 | Report a Bug | By Email