Bug 65311 - please prefer PT 101 for telephone-event:8000 to improve interop
Summary: please prefer PT 101 for telephone-event:8000 to improve interop
Status: RESOLVED FIXED
Alias: None
Product: Farstream
Classification: Unclassified
Component: RTP Plugin (show other bugs)
Version: unspecified
Hardware: Other All
: medium normal
Assignee: Simon McVittie
QA Contact: Olivier Crête
URL:
Whiteboard:
Keywords: patch
Depends on:
Blocks: 65131
  Show dependency treegraph
 
Reported: 2013-06-03 19:08 UTC by Simon McVittie
Modified: 2013-06-03 19:37 UTC (History)
0 users

See Also:
i915 platform:
i915 features:


Attachments
Prefer dynamic PT 101 for telephone-event at clock rate 8000 (2.17 KB, patch)
2013-06-03 19:08 UTC, Simon McVittie
Details | Splinter Review

Description Simon McVittie 2013-06-03 19:08:19 UTC
Created attachment 80243 [details] [review]
Prefer dynamic PT 101 for telephone-event at clock rate 8000

The WebRTC implementation in Google Chrome <= 26 would reject calls
if there was "a telephone-event payload type less than 101"[1] and
as of 2013-06-03, the Google Mail web UI with the VoIP extension
seems to have a similar signalling bug. Experimenting with the web UI
indicates that telephone-events with clock rate != 8000 are irrelevant,
and only clock rate 8000 matters. Hopefully the same was true in WebRTC
(I can't find a libjingle commit that looks likely to have fixed this).

Meanwhile, many SIP implementations and at least one Jingle
implementation (Freeswitch's mod_dingaling) either hard-code payload
type 101 to be telephone-event, or make the payload type for
telephone-event a configuration option. I can't help thinking this
was not how dynamic payload types were meant to work, but
interoperability is interoperability...

This fixes interop when Empathy 3.8 + telepathy-gabble 0.17.4, on a
system with not many codecs installed) calls the Google Mail web
UI. When the same setup is called by a peer that specifies a different
PT for telephone-event:8000 (the Google Mail web UI uses 126 in its
outgoing calls), the peer's choice of PT takes precedence.

[1] https://code.google.com/p/webrtc/issues/detail?id=1783
Comment 1 Olivier Crête 2013-06-03 19:37:12 UTC
Committed

commit 6e899cdc8210aa28fec63cce0de65338c73234d2
Author: Simon McVittie <simon.mcvittie@collabora.co.uk>
Date:   Mon Jun 3 20:06:53 2013 +0100

    Prefer dynamic PT 101 for telephone-event at clock rate 8000


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