Re: [rtcweb] Review comments on draft-ietf-rtcweb-fec-04

Hi Roni,

Not following you. Neither RFC 5265 nor RFC 5265-bis references 
red/audio, also webrtc-rtp-usage references the fec draft when speaking 
about redundancy.

Also, please note that I am not proposing to change current RED behavior 
or its usage within webrtc, just proposing to add a "warning" note to 
make it implicit what is the current situation: When using rtp red for 
audio, only payload is protected, and rtp headers are not, which is 
almost harmless currently but could cause some issues in the future if 
not taken into consideration when using new rtp header extensions.

Best regards
Sergio

On 24/04/2017 7:43, Roni Even wrote:
>
> Hi Justin,
>
> I am not sure that this is something to discuss here, RTP header 
> extensions are discussed in 
> https://tools.ietf.org/html/draft-ietf-rtcweb-rtp-usage-26 , which 
> points to RFC5285 soon to be replaced  by the rfc5285-bis draft.
>
> The bis draft has a section about transmission considerations see 
> https://tools.ietf.org/html/draft-ietf-avtcore-rfc5285-bis-09#section-4.1.1discussing 
> reliability of RTP header extension delivery by sending them in 
> multiple RTP packets.
>
> If you still want to say something you can probably add to section 1 “ 
> Web Real-Time Communication (WebRTC) Media Transport and Use of RTP 
> are discussed in 
> https://tools.ietf.org/html/draft-ietf-rtcweb-rtp-usage-26”
>
> Roni
>
> *From:*Justin Uberti [mailto:juberti@google.com]
> *Sent:* יום א 23 אפריל 2017 21:48
> *To:* Roni Even
> *Cc:* Sergio Garcia Murillo; rtcweb@ietf.org
> *Subject:* Re: [rtcweb] Review comments on draft-ietf-rtcweb-fec-04
>
> On Sat, Apr 22, 2017 at 10:32 PM, Roni Even <roni.even@huawei.com 
> <mailto:roni.even@huawei.com>> wrote:
>
> Hi,
> Inline
> Roni Even
>
> > -----Original Message-----
> > From: rtcweb [mailto:rtcweb-bounces@ietf.org 
> <mailto:rtcweb-bounces@ietf.org>] On Behalf Of Sergio Garcia
> > Murillo
> > Sent: יוםו 21 אפריל 2017 12:30
> > To: rtcweb@ietf.org <mailto:rtcweb@ietf.org>; Justin Uberti
> > Subject: [rtcweb] Review comments on draft-ietf-rtcweb-fec-04
> >
> > Hi all, Justin,
> >
> > I have been reviewing current FEC draft and I have a couple of comments:
> >
> > 1. Usage of RED and in band FEC and header extensions in Sections 3.2,
> > 3.3 and 4
> >
> > I think it would be worth noting that neither red/audio nor in-band 
> fec allows
> > to recover RTP header extensions from previous packets. The impact of
> > loosing the header extensions will be dependent of its meaning as, for
> > example, this would cause minor problems to SFUs as client to mixer 
> audio
> > level info of previous packets will be lost, but could make it 
> unusable for
> > PERC (as it is currently defined) as it requires the OHB header 
> extension.
>
>
> [Roni Even] This is not a FEC problem but general RTP header 
> extensions reliability discussed in RFC5285 and RC5285-bis draft and 
> in the specific RTP header extension.
>
> Roni, what would you suggest we say in this document?
>
>     >
>     > 2. Adaptive use of FEC for bandwidth probing (section 8)
>     >
>     > I think it would be a good addition to recommend FEC usage for
>     bandwidth
>     > proving instead of other alternatives like RTX or padding only
>     packets.
>     >
>     > Best regards
>     >
>     > Sergio
>     >
>     > _______________________________________________
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>     > rtcweb@ietf.org <mailto:rtcweb@ietf.org>
>     > https://www.ietf.org/mailman/listinfo/rtcweb
>