Hi Emil, Matthew,
I'm quite sure how to realize such a "remote bugfix", as it could
overlap with locally define codecs...
By the way, I've seen this behavior with Jitsi (aka. SIP communicator).
However, my snom 360 behaves correctly.
Neither of the other UAs I have ever used do expose such a missbehavior.
Matthew: were you using Jitsi (possibly the osx versiob ;-))? If yes, we
should definitely file a bug report.
Cheers
Raphael.
On 11.06.11 17:53, Emil Kroymann wrote:
Hi Matthew,
I think in this case it is the peer behaving incorrectly. The peer
should send under the payload types offered by SEMS and SEMS vice-versa
under the payload types given in the answer.
Still it seems to be desirable for interoperability, if SEMS would
match the payload types given by the peer. In the case where SEMS is
generating the SDP offer, this is not possible, however.
Regards,
Emil
Am Sat, 11 Jun 2011 11:02:10 -0400
schrieb Matthew Williams<[email protected]>:
Hi,
I think I'm finding a very similar issue with payload types for
telephone-events. If this is unrelated, please accept my apologies.
A peer is sending an INVITE with a payload type of '101' for
telephone-events. In SEMS' reply (200 OK), payload type '96' is
indicated for telephone-events. When the peer sends an event with
type 101, SEMS rejects it as unknown type. I was actually expecting
SEMS to reply with the same payload type (101), but from what you're
saying, it seems the sdp itself is acceptable, but the fact that SEMS
is rejecting payload type 101 is not? Or is it the peer that should
be sending as type 96, since this is what was in the SDP reply?
I am working with latest master
(856a7428eaea24a426688b277b2d504b4cb1f798).
Regards,
Matthew Williams
On Sat, Jun 11, 2011 at 7:05 AM, Emil Kroymann
<[email protected]>wrote:
Hi,
I think I found a problem with the SDP offer-answer implementation
recently merged into master while implementing wideband
functionality. The problem is with the assignement of dynamic
payload types. SEMS seems to keep only one mapping of dynamic
payload types to codec implementation, which is global to all of
SEMS. However, it should keep two separate mappings - one for
sending and one for receiving - for each RTP stream. This problem
shows in the following setup:
I use twinkle to setup a call to SEMS, which plays an announcement
using the speex wideband codec. Twinkle sends the following SDP
in the INVITE:
v=0.
o=twinkle 1229564934 1632772146 IN IP4 192.168.1.121.
s=-.
c=IN IP4 XX.XX.XX.XX.
t=0 0.
m=audio 13006 RTP/AVP 98 97 8 0 102 3 101.
a=rtpmap:98 speex/16000.
a=rtpmap:97 speex/8000.
a=rtpmap:8 PCMA/8000.
a=rtpmap:0 PCMU/8000.
a=rtpmap:102 G726-16/8000.
a=rtpmap:3 GSM/8000.
a=rtpmap:101 telephone-event/8000.
a=fmtp:101 0-15.
a=ptime:20.
a=nortpproxy:yes.
This means, that twinkle expects the speex wideband codec under
payload type 98 and the speex narrowband codec under payload type
97.
SEMS answers with the following SDP in the 200 OK:
v=0. o=sems 1 1 IN IP4 XX.XX.XX.XX.
s=sems.
c=IN IP4 89.246.236.49.
t=0 0.
m=audio 10000 RTP/AVP 97 96 8 0 101.
a=rtpmap:97 speex/16000.
a=rtpmap:96 speex/8000.
a=rtpmap:8 PCMA/8000.
a=rtpmap:0 PCMU/8000.
a=rtpmap:101 telephone-event/8000.
This means, that SEMS expects the speex wideband codec under payload
type 97 and the speex narrowband codec under payload type 96.
Unfortunately, SEMS sends speex wideband encoded RTP packets with
payload type 97. This leads to twinkle decoding the audio with the
narrowband decoder and to poor audio quality.
As mentioned above, to fix the problem, SEMS has to keep a seperate
payload type mapping for sending and it has to set the payload type
on outgoing packets according to this mapping.
Since we need this functionality at ISACO quite urgently, I would be
willing to implement a fix for this.
What do you think?
Regards,
Emil
--
Emil Kroymann
VoIP Services Engineer
Email: [email protected]
Tel: +49-30-203899885
Mobile: +49-176-38389303
ISACO GmbH
Kurfürstenstraße 79
10787 Berlin
Germany
Amtsgericht Charlottenburg, HRB 112464B
Geschäftsführer: Daniel Frommherz
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