IETF Logo Mail Archive

Re: [codec] RTP Payload Format and File Storage Format for Opus Speech and Audio Codec - draft-spittka-payload-rtp-opus-00

"Benjamin M. Schwartz" <bmschwar@fas.harvard.edu> Tue, 05 July 2011 16:39 UTC

Return-Path: <bmschwar@fas.harvard.edu>
X-Original-To: codec@ietfa.amsl.com
Delivered-To: codec@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 4F4FC11E816C for <codec@ietfa.amsl.com>; Tue, 5 Jul 2011 09:39:05 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.399
X-Spam-Level:
X-Spam-Status: No, score=-2.399 tagged_above=-999 required=5 tests=[BAYES_00=-2.599, J_CHICKENPOX_15=0.6, J_CHICKENPOX_36=0.6, RCVD_IN_DNSWL_LOW=-1]
Received: from mail.ietf.org ([64.170.98.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id i4-tfC1i5Z4u for <codec@ietfa.amsl.com>; Tue, 5 Jul 2011 09:39:03 -0700 (PDT)
Received: from us25.unix.fas.harvard.edu (us25.unix.fas.harvard.edu [140.247.35.201]) by ietfa.amsl.com (Postfix) with ESMTP id AC5AA11E8166 for <codec@ietf.org>; Tue, 5 Jul 2011 09:39:02 -0700 (PDT)
Received: from us25.unix.fas.harvard.edu (localhost.localdomain [127.0.0.1]) by us25.unix.fas.harvard.edu (Postfix) with ESMTP id 057BD1D7688; Tue, 5 Jul 2011 12:39:01 -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=xuGAz4GvS+J96IC moTKX6vrCqI59D0YsHXKtdDUPLGo=; b=POekWGqwWQnk7CFv8FUvNYuie9iMKPF wLVpxITLnaryF4wK+8oMkwj/ehm+zBmJm2HNBTq+xLBtRSGa7UQvWPsPsLP3riEi roD77elA+9YLWk/iR4kIn0iOouVCqGS2aUF/IuGBBBP8wc1uzS7YbnBekKkq/cs4 fH5FvrC1fP/Y=
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=bEbEPPeev zsI2P73NbzIrY1N0p6MACiSyC67lYmM23x3AVjG8RQkSR2gtJu1fiLnbIJzbV1by Ayy7gihzSE+h81gRap6lP4NXznVnkTDUoA0Kb3ZGS0O4z9w715IezRgnjTm1s5zP ZXZC9HfQ06v7SUypbwzbc5XI+hooCEWsQ0=
Received: from [172.23.141.64] (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 us25.unix.fas.harvard.edu (Postfix) with ESMTPSA id EEE611D766B; Tue, 5 Jul 2011 12:39:00 -0400 (EDT)
Message-ID: <4E133E21.3050001@fas.harvard.edu>
Date: Tue, 05 Jul 2011 12:38:57 -0400
From: "Benjamin M. Schwartz" <bmschwar@fas.harvard.edu>
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.17) Gecko/20110424 Lightning/1.0b2 Thunderbird/3.1.10
MIME-Version: 1.0
To: julian.spittka@skype.net
References: <00f501cc3aa7$551264c0$ff372e40$@spittka@skype.net>
In-Reply-To: <00f501cc3aa7$551264c0$ff372e40$@spittka@skype.net>
X-Enigmail-Version: 1.1.2
Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="------------enig4389EB404A45ED6ED287F42C"
Cc: codec@ietf.org
Subject: Re: [codec] RTP Payload Format and File Storage Format for Opus Speech and Audio Codec - draft-spittka-payload-rtp-opus-00
X-BeenThere: codec@ietf.org
X-Mailman-Version: 2.1.12
Precedence: list
Reply-To: bens@alum.mit.edu
List-Id: Codec WG <codec.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/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: Tue, 05 Jul 2011 16:39:05 -0000

On 07/04/2011 08:06 PM, Julian Spittka wrote:
> Any feedback, questions, or comments are highly welcome.

Thank you for doing this work.  I think your proposed RTP and SDP formats
are very nice and a good step for us.

I have a few comments.

1.  I think the description of Opus should be removed.  There's no need to
duplicate the contents of the Opus RFC.

2.  I think the payload specification should make (almost) no mention of
Opus frames, modes, etc.  These aspects of Opus are entirely internal to
the payload, which is a "black box".  As far as the RTP specification is
concerned, Opus consists of (almost-)arbitrary-duration "packets" and
that's it.

3.  To avoid confusion, I think we should be very careful and clear about
the distinction between audio bandwidth and samplerate, as their
relationship in Opus is far from simple.

I have implemented these ideas, along with a few minor changes, as a patch
to the draft .xml, attached.  Please feel free to discard this patch; I
mean it only as a way to communicate my suggestions more clearly.

--Ben

v2.23.0 | Report a Bug | By Email