Ethereal-users: Re: [Ethereal-users] RTP Analysis: Error: "Can't save in a file:Unsupported code
It seems to me that if the developers would go as far as to put the
functionality to reassemble rtp packets to audio, that they have
already stretched the definition of a packet sniffer. Why not go the
extra step and make the feature more robust? In its current form, I
would say its broken, if the simple act of pushing a "1" during the
conversation, breaks the ability to save the file. (without filtering
out the DTMF packets). Just my two cents.
On Thu, 17 Mar 2005 14:45:33 -0500, Scott Lowrey <slowrey@xxxxxxxxxxx> wrote:
> Cool idea, but what this amounts to is almost equivalent to implementing a
> proper RTP layer within Ethereal. To "insert silence" means analyzing the
> special event (DTMF), and *generating* the silence. This is not trivial nor
> should this functionality be provided by a utility like Ethereal.
>
> I'm not an Ethereal expert and there may be a way to get this to work, but
> it seems like we're stretching the definition of a packet sniffer a bit.
> The thing is that RTP can be quite complex - it's rarely a simple bitstream
> that can be assembled into a .wav file.
>
> Still, Ethereal continues to amaze me so I don't want to dampen enthusiasm.
> :)
>
> Maybe a better idea would be to create a small app that combines libpcap
> and GNU ccrtp...?
>
> Erik Naslund wrote:
>
> That's right. You shouldnt remove anything from the stream when you're
> interested in reconstructing it later (rtpdump/rtpplay). However, the "save
> payload" functionality should be modified in order to ignore anything that's
> not voice (voice=only G.711 for the moment) and that shouldn't disturb the
> audio content too much, does it? I think that's what he's talking about. I
> had no time to look at the capture file for the moment however.
> The audio
> content gets disturbed when you remove the DTMF packets. The more packets of
> this type, the more the timing of the conversation is off. Think about
> calling your credit card company, when you enter in your full CC #, plus
> following the menu prompts. This could cause the timing of the conversation
> to be off by several seconds. Again, if the Save Payload functionality could
> simply insert silence or false tones during the audio encoding process, this
> would preserve the timing of the conversation. IANAD but it would seem
> doable, as the DTMF packets seem very detailed as to how long the button is
> pressed, which button it is, and when it "ends". I am a very grateful user
> of a fabulous FOSS package. I dont want to come off as disgruntled or
> ignorant. Thanks for all the work everyone does on making ethereal such an
> awesome tool for sysadmins such as myself, as well as the casual home user.
> You guys are great. -Erik _______________________________________________
> Ethereal-users mailing list Ethereal-users@xxxxxxxxxxxx
> http://www.ethereal.com/mailman/listinfo/ethereal-users
>
> --
> Scott Lowrey
> Test Engineering Manager
> NexTone Communications
> Gaithersburg, Maryland USA
>
> 1.240.912.1369
>
