IETF Logo Mail Archive

Re: [rtcweb] FEC for audio?

Justin Uberti <juberti@google.com> Mon, 19 May 2014 21:36 UTC

Return-Path: <juberti@google.com>
X-Original-To: rtcweb@ietfa.amsl.com
Delivered-To: rtcweb@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 959601A038B for <rtcweb@ietfa.amsl.com>; Mon, 19 May 2014 14:36:56 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.029
X-Spam-Level:
X-Spam-Status: No, score=-2.029 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, FM_FORGED_GMAIL=0.622, HTML_MESSAGE=0.001, RP_MATCHES_RCVD=-0.651, SPF_PASS=-0.001] autolearn=ham
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 8YflomIr-bYm for <rtcweb@ietfa.amsl.com>; Mon, 19 May 2014 14:36:54 -0700 (PDT)
Received: from mail-vc0-x22b.google.com (mail-vc0-x22b.google.com [IPv6:2607:f8b0:400c:c03::22b]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 17D0F1A0176 for <rtcweb@ietf.org>; Mon, 19 May 2014 14:36:54 -0700 (PDT)
Received: by mail-vc0-f171.google.com with SMTP id lc6so10386978vcb.30 for <rtcweb@ietf.org>; Mon, 19 May 2014 14:36:53 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type; bh=xjoi6nGmus8HkLzNhOMm+r3Uz2Su+p6VsZMg/vdDcB4=; b=LwSDwWktVSnUUyWWRYUSoAYk2Ngf8LFDjyQYjhSLeRT4XSj183qCsevR/lKhS71keG dG1w47l+fgzhSMapsTPmFJEMbdFv46+/Au6cfNsDxa2dP1Jc++k44AbmfFx67JenL0sD aB3DpnLnYIDq/q0PxMA+27PHX6RsrLWm+npneD+ddhF9NVeHJQknZWhQxtDsZ046tAAO t5lMLzwwrBmXg2aalpnJzRTscIZb+tdEBip0GGVaOj/sIeZIfugb8A2cmShVfMDjVUoc M5L0fcFJZTawgUhnK4S2BPQqieqTMIFUyA6tCjTGnAzd2F9PR3hqJHwKGWVmwdY7mXY0 m/IA==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc:content-type; bh=xjoi6nGmus8HkLzNhOMm+r3Uz2Su+p6VsZMg/vdDcB4=; b=aTphNmhpnGPu+VS9OClQcSBSVd5Y5AKvGEpaFXAOUExcVqo0QVBJ34RWPQJtJ0+kaZ yNmvPwdWCS/l9UXU+3a/60UiNTuUsFCR5uf6jBWzQplE6Zj68Q72dn7UcR4rYTtWEQJr P+h9U8OxEZ7YMlTzXMTiHT+zldSfTxR22KqXIQXBHAwlNUqrCW9zYh+H0NDwcNQanmKm eByOPRPc7eFqF7saEbZa29SsWbNgV4k/zdhheERyZINL7aGfgTZgbXsN3jd1DfDKlmJb opU+NLUHLQTfwoaRy4BIlfXU+X4MNHYRpJ0HONtEsgA6B0LsPivCR8E4F3movDttWEFM pdlw==
X-Gm-Message-State: ALoCoQlKLjelAPiZCpnSbReSJf8a7+x2KlpEFTrBlAQUSbIlE9zZczpG/vhI1xhDrQFfvpVXgik2
X-Received: by 10.52.124.66 with SMTP id mg2mr307013vdb.50.1400535413409; Mon, 19 May 2014 14:36:53 -0700 (PDT)
MIME-Version: 1.0
Received: by 10.52.145.105 with HTTP; Mon, 19 May 2014 14:36:33 -0700 (PDT)
In-Reply-To: <CAOJ7v-2mb6DkakaEWMxJwqqLSePb7NrOcF-DSycW-CftBGdmcA@mail.gmail.com>
References: <CAOJ7v-1qEpkWShmw1SQKh4_BLKycF=egu42TS9o9+Smtof36pg@mail.gmail.com> <CAJrXDUESUa-xm9y22OAVKAw5z=WnkY4-X6XFZOoXwvkMoDnaoQ@mail.gmail.com> <537A6190.4060709@mozilla.com> <CAOJ7v-2mb6DkakaEWMxJwqqLSePb7NrOcF-DSycW-CftBGdmcA@mail.gmail.com>
From: Justin Uberti <juberti@google.com>
Date: Mon, 19 May 2014 14:36:33 -0700
Message-ID: <CAOJ7v-1YxHhVm8NE4H3ZkCuOtN4CsUgQoiV1GN3w3NKRWhqWMw@mail.gmail.com>
To: "Timothy B. Terriberry" <tterriberry@mozilla.com>
Content-Type: multipart/alternative; boundary="bcaec5299745cfe05004f9c78f04"
Archived-At: http://mailarchive.ietf.org/arch/msg/rtcweb/yQkl-fMrYziIevldqBZ1RCdcz2s
Cc: "rtcweb@ietf.org" <rtcweb@ietf.org>
Subject: Re: [rtcweb] FEC for audio?
X-BeenThere: rtcweb@ietf.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: Real-Time Communication in WEB-browsers working group list <rtcweb.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/rtcweb>, <mailto:rtcweb-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/rtcweb/>
List-Post: <mailto:rtcweb@ietf.org>
List-Help: <mailto:rtcweb-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/rtcweb>, <mailto:rtcweb-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 19 May 2014 21:36:56 -0000

On Mon, May 19, 2014 at 2:36 PM, Justin Uberti <juberti@google.com> wrote:

>
>
>
> On Mon, May 19, 2014 at 12:54 PM, Timothy B. Terriberry <
> tterriberry@mozilla.com> wrote:
>
>> Peter Thatcher wrote:
>>
>>> Is there a good reason not to support FEC for audio, if that's what the
>>> application wants?
>>>
>>
>> I can't think of one. I think we should support FEC for audio.
>>
>>  On Mon, May 19, 2014 at 9:44 AM, Justin Uberti <juberti@google.com
>>> <mailto:juberti@google.com>> wrote:
>>>     Should we specify generic FEC for audio as well as video? Opus has
>>>     built-in FEC, but it only works for the SILK portion of the payload,
>>>     meaning that in high bitrate situations, it won't do much for you. I
>>>     don't know if it has benefits over generic FEC.
>>>
>>
>> The built-in FEC for the SILK layer was meant to cover the case where you
>> wanted FEC with no more than one extra frame of latency, but did not want
>> to double your bitrate. The reason we did not add built-in FEC for the CELT
>> layer was that at the bitrates where CELT operates, we assumed traditional
>> codec-agnostic FEC would be used, and thought it an adequate solution
>> compared to the extra complexity a codec-specific solution would have
>> required.
>>
>>
> Thanks, that's very helpful. This means that if the app says "do FEC", and
> the remote side supports opus inband FEC, and the data rate is < XX kbps,
> we'll use the inband FEC instead of generic FEC.
>

Advice on the exact value of XX welcomed.

v2.23.0 | Report a Bug | By Email