All things related to multicast

[Frank Fulchiero <>]

Hi Zenon,

If it's not too much trouble, I would like a demonstration of a SAP  
in VLC that when clicked plays an RTSP multicast H.264 MPEG4 stream.
If you don't want to run it for a long period of time, just let me  
know when the test will be.
Or at least run it locally, and let me know if it works.

What would you use to generate the SAP?

The reason I am asking if it's possible is that we would like to  
support the development of a small application to generate SAPs from  
the SDP files created by multicast RTSP from Wirecast, QuickTime  
Broadcaster, and Darwin Streaming Server/QT Streaming Server.
I realize the SDP files created from these apps may need some  
tweaking before being used to generate the SAP, as they may not be  
fully standard.
But before going ahead, we need to know if it's even possible to  
accomplish the above.

Thanks for all the info below...I am more at the encoding/usability  
end than the networking/protocol end of things, so this along with  
the other helful posts helps a lot.

Frank Fulchiero
Digital Media Specialist
Connecticut College

On Jun 13, 2008, at 9:14 AM, Zenon Mousmoulas wrote:

> Hi Frank,
>
> RTP payload format for H.264 video is defined in RFC3984. More  
> specifically you can look at sections 8.2 and 8.3:
>
>    An example of media representation in SDP is as follows (Baseline
>    Profile, Level 3.0, some of the constraints of the Main profile may
>    not be obeyed):
>
>       m=video 49170 RTP/AVP 98
>       a=rtpmap:98 H264/90000
>       a=fmtp:98 profile-level-id=42A01E;
>                 sprop-parameter-sets=Z0IACpZTBYmI,aMljiA==
>
> I took a H.264 video in quicktime MOV container (it's actually the  
> iPhone 3G ad from apple.com) and ran it through VLC creating an SDP  
> that looks like this:
>
> v=0
> o=- 1213359427288608 2 IN IP4 127.0.0.1
> s=test
> t=0 0
> a=tool:vlc 0.8.6h
> c=IN IP4 239.239.239.234/1
> m=video 1232 RTP/AVP 96
> a=rtpmap:96 H264/90000
> a=fmtp:96 packetization-mode=1;profile-level-id=4d401e;sprop- 
> parameter-sets=J01AHqkYGoe2ANQEBAbbCte98BA=,KN4JyA==;
> m=audio 1230 RTP/AVP 97
> a=rtpmap:97 mpeg4-generic/44100
> a=fmtp:97 streamtype=5; profile-level-id=15; mode=AAC-hbr;  
> config=1210; SizeLength=13;IndexLength=3; IndexDeltaLength=3;  
> Profile=1;
>
> As you can see, the payload type depends on the H.264 level/ 
> profile. The semantics are all in there, encrypted in the RFC :)
>
> I believe VLC does play this once it sees the SAP announcement. We  
> can test it if you want (but I won't leave this running for now).
>
> HTH,
> Z.