Fransisco,
I am currently mulling over how best to
arrange to dynamically identify UDP traffic as
RTP, given that many mechanisms that use SDP to
describe their sessions actually use lower level
protocols ( like MGCP ) to signal whether we are setting up, tearing
down, or modifying a connection. My primary current interest is
in dynamically identifying the RTP streams associated with
various VoIP protocols ( MGCP, and to a lesser degree SIP ), but
I would be very interested in working with you on meeting your
needs as well, since what you are proposing sounds interesting to
me. Could you be a little more specific about what you
are trying to acheive? Are you talking about using
the rtp-map media attributes from SDP to define these 'dynamic' rtp
payload types?
Ed
On Sat, 2002-01-05 at 15:02, Francisco Javier Cabello wrote:
> Hello,
>
> I would like to add ethereal knowing about rtp dynamic payloads.
> I don't know so much about ethereal architecture, because of that I need some
> help to implement this feature.
> I'll try to explain the problem. RTP defines a number for each payload which
> is coded in the RTP header. Ethereal reads this payload number from rtp
> header and call to one of the RTP dissectors which have been registered. The
> problem is when payload number is a 'dynamic payload', in these cases, we
> don't know which is the format packetized in the RTP packets, and because of
> that we don't know which dissector have to call. To know it, we need search
> in the SDP information. One of the solution could be:
> In packet-rtp.c, when we have to dissect rtp packet and I see that it's a
> dynamic payload rtp packet, we could ask to 'SDP' module about the last
> RTSP/SDP negotiation, and there, look for information which is coded as a
> 'Media attribute field'.
>
> Any ideas? Thanks.
>
> Regards.
>
> Francisco J. Cabello.
>
>
>
>
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