Brent Harsh asked:
"Now, a question for the group: when using a payload type that doesn't
conform to one of the known values (ie, 0 for G711ulaw, 8 for G711alaw, or
18 for G729 etc...) ethereal will not decode the stream. We use a negotiated
value for a clear-channel data stream and in order to hear it, I use a perl
script (or a regexp in xemacs in binary mode!) to replace the payload type
byte in all the RTP packets with a 00. This works fine, but it would be nice
if ethereal had a way to specify the pt used for x-ccd (or even if you just
wanted to "force" it to decode anyway). I just started using ethereal, so am
not terribly familiar with it yet - perhaps this functionality is in there
somewhere already?"
Where dynamic payload types are used, it should be possible, at least in
some cases, to automatically store in the conversation associated with the
RTP stream the actual payload type. e.g. if the stream is setup using SDP,
regardless of the acual payload type number that is sent, if an attribute
entry says the contents are PCMU, this information could be associated with
the stream and made use of:
- while parsing the RTP packets, for display and for calling any appropriate
subdissectors
- while tring to do "Save Payload".
This hasn't been implemented yet, but I know at least one person was
interested in working towards this.
Regards,
Martin
