Re: sdp_remove_media() always uses the original message, right?

Hello Benoit,

as mentioned e.g. in our FAQ, it's best to apply changes to a specific part of the message only time, or to apply msg_apply_changes() in between.
Otherwise, there is larger change for a possible corruption. Even if it works stable in your specific configuration, it could stop working e.g. after a major update where some internals are changed.

https://www.kamailio.org/wikidocs/tutorials/faq/main/#why-body-or-other-parts-of-the-sip-message-appear-multiple-times

Look to the earlier FAQ topics for an explanation of the technical reasons.

Cheers,

Henning 

> -----Original Message-----
> From: Benoit Panizzon via sr-users <[email protected]>
> Sent: Donnerstag, 19. Februar 2026 08:43
> To: Ihor Olkhovskyi via sr-users <[email protected]>
> Cc: Benoit Panizzon <[email protected]>
> Subject: [SR-Users] Re: sdp_remove_media() always uses the original
> message, right?
> 
> Hi Ihor
> 
> > In theory for every media type you have a separate m= line. So, knowing
> how
> > lumps system in Kamailio is working, it's ok not to
> > call msg_apply_changes() in between, as you are not modifying the SAME
> > lines,
> 
> Ok, so this probably explains the seemingly inconsistend behaviour I
> observed.
> 
> sdp_remove_media("video");
> sdp_remove_media("image");
> 
> without calling msg_apply_change() works!
> 
> But:
> 
> SDP contains: PCMA,PCMU,G729,OPUS,AMR-WB
> 
> Determine we want to remove low quality and US codec form A leg:
> 
> sdp_remove_codecs_by_name(PCMU,G729);
> 
> performing routing, finding out B needs some codecs removed:
> 
> sdp_remove_codecs_by_name(AMR-WB,opus,t38);
> 
> Will revert removal of PCMU and G729 if no msg_apply_changes() is
> called in between, right?
> 
> Mit freundlichen Grüssen
> 
> -Benoît Panizzon-
> --
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