SDP works

[bennylp]

• generation of SDP
  • how codec can put codec specific info in SDP?
• codec specific SDP negotiation, if any
• applying parameters in SDP to the codec

TODO:

1. add video SDP generation in pjmedia_endpt_create_sdp()
2. add video stream info generation from SDP in pjmedia_stream_info_from_sdp()
3. add codec specific negotiation, perhaps sdp_neg.c should have external format negotiation mechanism to handle format specific negotiation, e.g: H26x picture resolution negotiation, this negotiation result will be applied to codec param (for stream in opening the codec)
4. add auto-assignment mechanism for dynamic payload type (in endpoint when creating SDP?), currently, the space for hardcoded dynamic payload type is very tight (or even not enough for video formats)
5. auto apply (or at least validate) SDP fmtp setting to codec param (or the other way around?), e.g: when SDP fmtp setting in codec is set to "CIF=1" codec param should be set to "size=352x288 & fps=30/1.001"
6. add video capability to simpleua to test video stuffs on real SIP application