Re: no sound during playback of amr call

[Anders Broman <anders.broman () ericsson com>]

From: wireshark-dev-bounces () wireshark org [mailto:wireshark-dev-bounces () wireshark org] On Behalf Of Rahul Rohit
Sent: den 24 april 2014 14:34
To: Developer support list for Wireshark
Subject: Re: [Wireshark-dev] no sound during playback of amr call

> Hi,
> What I understood is that  to check playback feature for every standard payload type of RTP we need codecs specific  
> to that standard .By default wireshark has codec only for RTP payload type 0 and >8(G.711 A class and U class) and 
> doesn't have codecs for remaining payload types
(including dynamic payload stream 96).

Payload type 0 - 95 have fixed codec mapping, 96 - 127 are dynamic - e.g the payload type to codec mapping is dynamic 
and decided by out-of-band means, in SIP by SDP in SIP signals.
So payload type 96 MAY be G711 depending what's been signaled (or set) between the two RTP end points but most probably 
not as G711 have a fixed payload type.
So you can't say that Wireshark does not have a codec for PT 96, it does not have a codec for the media sent as payload 
type 96 in that particular call.

> Is this true that we can't check the playback functionality in Wireshark without having a licensed/patented codec for 
> any particular standard of RTP other than G.711 A class and U class ?

To play RTP content you need a codec, and the only available codecs in Wireshark are G711a and G711u, so yes.

> P.S.:  In  Wireshark we've added a preference setting in GUI  to receive RTP packets over UDP depending on the port 
> values. We are not using "decode
> as" functionality.

Thanks
Rahul Rohit





From: wireshark-dev-bounces () wireshark org<mailto:wireshark-dev-bounces () wireshark org> 
[mailto:wireshark-dev-bounces () wireshark org] On Behalf Of Anders Broman
Sent: Thursday, April 24, 2014 4:28 PM
To: Developer support list for Wireshark
Subject: Re: [Wireshark-dev] no sound during playback of amr call

Hi,
I'm not sure what you are after.

To playback an (audio) RTP stream the player must support the codec used. Currently Wireshark does only support 
playback of G711A/U
(see http://wiki.wireshark.org/RTP_statistics and http://wiki.wireshark.org/VoIP_calls ) you can add codecs to 
C:\wireshark\plugins\easy_codec or C:\wireshark\codecs
Unfortunately I don't know the details of doing it. Note that many codecs come with licenses an patents that make it 
difficult to use them in OpenSource.

> From "RTP dynamic payload stream(PT_UNDF_96)" I guess that you don't have the setup information of the RTP stream in 
> your trace and have done decode as RTP. As far as I know currently there is no way to "tell" Wireshark which codec is 
> used for payload type > 96. Perhaps something like that should be added. An UAT table to specify src/dst IP/port and 
> PT = xxx in the RTP dissector perhaps.
Note that in theory Payload type mapping might differ per call. Device A might propose AMR as PT = 96 and device B 
might use 101.

Some payload dissectors allow you to specify which PT they are tied to, check the preferences of the AMR dissector.
Regards
Anders

From: wireshark-dev-bounces () wireshark org<mailto:wireshark-dev-bounces () wireshark org> 
[mailto:wireshark-dev-bounces () wireshark org] On Behalf Of Rahul Rohit
Sent: den 24 april 2014 11:31
To: Developer support list for Wireshark
Subject: Re: [Wireshark-dev] no sound during playback of amr call

Hi,
Is there any way by which Wireshark be made to support play back for the RTP dynamic payload stream(PT_UNDF_96)by 
performing any change in the code or Wireshark.

Regards
Rahul Rohit



From: wireshark-dev-bounces () wireshark org<mailto:wireshark-dev-bounces () wireshark org> 
[mailto:wireshark-dev-bounces () wireshark org] On Behalf Of Rahul Rohit
Sent: Wednesday, April 23, 2014 1:08 PM
To: Developer support list for Wireshark
Subject: [Wireshark-dev] no sound during playback of amr call

Hi,
We are playing back an AMR voice call in Wireshark using telephony option but unfortunately no sound is audible. Could 
somebody please help us as to what might be the probable reason for this.


Regards
Rahul Rohit
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