[Live-devel] parseSDPAttribute_fmtp

[Ross Finlayson]

>         I need to parse an fmtp line with parameters specific to a codec; 
> i can't decide if I should append to the MediaSubsession class, or make 
> the method virtual so that I can call a subclass'd method to look for 
> certain parameters.  poking around the test code doesn't seem to show any 
> example uses of parseSDPAttribute_ftmp.

You mean "parseSDPAttribute_fmtp" (note the spelling!).  This is called 
from within "MediaSession::initializeWithSDP" to check for the presence of 
various attributes set in SDP "a=fmtp:" lines.

The set of 'fmtp' attributes that the code currently checks isn't 
exhaustive, so if you have a new attribute that you'd like the code to 
check, then please submit a patch (to "include/MediaSession.hh" and 
"MediaSession.cpp"), and I'll consider adding it to the source code 
release.  (However, if your attribute is for a private RTP payload format 
that's not documented by a RFC or Internet Draft, then I may be less 
inclined to add it.)

>   What do formats do that have specific parameters -- is there a 
> different line used?

No (if I understand your question correctly), "a=fmtp:" is used for all 
codec-specific parameters.

>   I noticed MPEG-4 video streams have a parseGeneralConfigStr, which is a 
> global method, which also intrigues me a bit...

That function merely converts the value of the "config" attribute (a 
character string of hex digits) into a corresponding chunk of binary data 
(that the MPEG-4 codecs use to initialize).


	Ross Finlayson
	LIVE.COM
	<http://www.live.com/>