[Live-devel] Modifying LiveMedia RTSPServer classes to support URI parameters

[Ross Finlayson]

>>For example (to use your example string), 
>>"live_video?height=320&width=400&kbps=300&fps=15" would use a 
>>completely separate "ServerMediaSubsession" (subclass) object than 
>>"live_video?height=320&width=400&kbps=300&fps=30".
>>
>This seems infeasible as I want to be able support any number of 
>combination of all 4 of these parameters (plus more parameters like 
>GoP size etc).

No, it's completely feasible.  The trick is *not* to create all of 
the possible the "ServerMediaSession" (and "ServerMediaSubsession") 
objects upfront, but instead to create them 'on demand', when needed. 
This is what we do for the "LIVE555 Media Server" application, using 
the "DynamicRTSPServer" class - which subclasses "RTSPServer" and 
reimplements the virtual function "lookupServerMediaSession()". 
(Note the code in the "mediaServer" directory.)  You could do 
something similar.


>Seems much more reasonable to have one subclass of 
>ServerMediaSession and ServerMediaSubsession that can read and 
>interpret the parameters on a per connection basis.

Well, the problem with that is - as you've discovered - that the 
"ServerMediaS(ubs)ession" objects are assumed to each represent a 
single 'media object' that you're streaming - e.g., a file.  If you 
open another stream with different codec parameters, it's 
conceptually like streaming from a different file.

Either way will probably work, but I suspect that you'll find it 
easier to use a different "ServerMediaS(ubs)ession" object for each 
parameter combination - but create these on demand.
-- 

Ross Finlayson
Live Networks, Inc.
http://www.live555.com/