Not sure, but perhaps this could work:
subst_body('/a=rtpmap:107 BV32/16000 /SAME_LINE\r\nNEW_LINE/');
In SAME_LINE you should use the typical variable to copy the match (maybe
$1)?
subst_body('/(a=rtpmap:107 BV32/16000) /\1\r\nNEW_LINE/'); like this it works :) thanks.
It should be possible to delete empty line with perl substitution, have no clue about how to do that.
Cheers