[Freeswitch-users] in bypass_media mode, 2833 payload type modified by freeswitch!

Kristian Kielhofner kris at kriskinc.com
Thu Jun 16 17:51:59 MSD 2011

I didn't know about this parameter either.  Is it new?

I'd argue that it should be enabled by default when bypass_media is in
enabled.  If not, it leaves open cases such as this one where you
can't win - some parameters of the SDP will be changed but not others?

If FreeSWITCH is completely rewriting the SDP and handling the media
to account for differences in the RTP streams that's fine (normal
media mode).

If FreeSWITCH is rewriting some SDP params without handling the media
it leaves the endpoints in a broken state that no one would ever want.
 In this case FreeSWITCH changed the SDP to say 2833 is payload type
101 when the RTP stream from the remote end would clearly have it at
payload type 110!  The endpoints would end up completely confused...

I think this parameter has some purpose and I always enjoy having
extra knobs to turn.  However, it should be enabled by default when
bypass_media is in use (to be disabled selectively by users in cases
where they need to, for some reason).

What about proxy_media?  As far as I can tell the same thing would
happen there (or worse).  The SDP would (probably) get changed and the
media would be proxied through FreeSWITCH but the RTP and SDP would
not agree on payload type (same as now).  From what it sounds like
this soa parameter is not compatible with proxy_media (hands off SDP)
so what would happen there?

On Wed, Jun 15, 2011 at 7:29 PM, Michael Collins <msc at freeswitch.org> wrote:
> And FTR, this *is* on the wiki - I just didn't know about it. :)
> http://wiki.freeswitch.org/wiki/Channel_Variables#SDP_Manipulation
> (Last item)
> -MC

Kristian Kielhofner

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