HMR - Altering SDP

I thought I posted, but don't see my message from earlier.  I resolved the issue myself, but still wanted to confirm the behavior.  I was trying to set the video port to 0 when the attribute for video was a=inactive.

 

Originally, I was trying to do a store and replace across multiple lines of SDP.  It appears that the manipulation on Content-Type can only do one line at a time.  Can someone confirm this?

 

If this is the case, what can be done to only manipulate attributes or other items for only one of the media types?  For instance, what if you have connection info (c= .....) for both audio and video and you want to place it only in the root part of the SDP?