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RE: [rtcweb] H.264 SVC and BUNDLE

From: Christer Holmberg <christer.holmberg@ericsson.com>
Date: Thu, 30 Aug 2012 09:50:35 +0200
To: Dan Wing <dwing@cisco.com>, "public-webrtc@w3.org" <public-webrtc@w3.org>, "rtcweb@ietf.org" <rtcweb@ietf.org>
Message-ID: <7F2072F1E0DE894DA4B517B93C6A05853409FF2F5C@ESESSCMS0356.eemea.ericsson.se>

Hi Dan,

Thanks for the information!

The issue you raise is of course not related to BUNDLE, but to multiplexing in general.

Regards,

Christer
________________________________________
From: Dan Wing [dwing@cisco.com]
Sent: Thursday, August 30, 2012 1:32 AM
To: Christer Holmberg; public-webrtc@w3.org; rtcweb@ietf.org
Subject: RE: [rtcweb] H.264 SVC and BUNDLE

> -----Original Message-----
> From: rtcweb-bounces@ietf.org [mailto:rtcweb-bounces@ietf.org] On
> Behalf Of Christer Holmberg
> Sent: Wednesday, August 29, 2012 11:50 AM
> To: public-webrtc@w3.org; rtcweb@ietf.org
> Subject: [rtcweb] H.264 SVC and BUNDLE
>
> Hi,
>
> At the telco yesterday one of the Microsoft guys claimed that H.264 SVC
> does not work with BUNDLE, but he didn't have the details.
>
> Could someone please explain the reason why he/she doesn't think H.264
> SVC work with BUNDLE?
>
> (Note, that if using the same port for the different codec layers is a
> problem, then it's not a BUNDLE problem - it's a generic multiplexing
> problem.)

The general multiplexing of layers onto the same 5-tuple is a problem,
*if* we want the layers to have different DSCP values.  This is because
we cannot successfully and reliably set different DSCP values for packets
belonging to a 5-tuple over the Internet -- too many things rewrite
the DSCP field (to a different value) or simply clear the DSCP field.
This makes it impossible to restore the per-packet DSCP values later
(e.g., using RSVP, or using any other better/stronger/faster signaling
method).  If, however, each 5-tuple has its own DSCP value then that
DSCP value could be restored.

-d

> Thanks!
>
> Regards,
>
> Christer
> _______________________________________________
> rtcweb mailing list
> rtcweb@ietf.org
> https://www.ietf.org/mailman/listinfo/rtcweb
Received on Thursday, 30 August 2012 07:52:21 GMT

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