Ethereal-users: Re: [Ethereal-users] RTP Analysis: Error: "Can't save in a file:Unsupported code
Erik Naslund wrote:
> OS: Windows 2000 Server
> WINPCAP Ver 2.3
> Ethereal Ver 0.10.10
> RTP Encoding: G.711
>
> I am a vonage customer, and am having some difficulty in saving
> certain RTP payloads to an audio file.
>
> This feature seems to work fine as long as no telephone buttons are
> pressed during the conversation. However, if a button is pressed and a
> tone generated, it seems to foul up the process, resulting in the
> error message in the subject line of this post.
I guess that the RTP-stream contains not just packets with payload type 0 (G.711 U-law) or payload type 8 (G.711 A-law)
but also packets with another payload type.
When DTMF digits are sent then they can be sent with a special codec (RFC 2833 RTP Events).
Probably there is packets with a dynamic payload type in the range 96 to 127.
You could probably avoid the problem by first using a display filter to only select the other packets that you
need and then save only the displayed packets with "Save As..." and then load that file and analyze it.
The filter could maybe look something like:
sip or sdp or h225 or h245 or rtp.p_type==0 or rtp.p_type==8
However not a really nice solution, so we should probably try to find a real solution to your problem (e.g.
alerting the user that the stream contains a mixture of payloads and that only the G.711 packets will be saved to
the au-file).
