[Live-devel] RTSP over UDP...

[Peter Maersk-Moller]

Hi Thomas

Thomas Christensen wrote:
> Hi Ross and fellow Live555 fans
> On 28/04/2006, at 22.36, Ross Finlayson wrote:
>>>>>does the live555 RTSP implementation support RTSP over UDP ?
>>>>No.  RTSP over UDP has never been standardized, and is not supported
>>>>at all (by anyone, actually).
>>>Would it be possible to do RTSP over UDP
>>Probably, but until such a thing is standardized by the IETF (which
>>may never happen), we will never support such a thing.
> Sorry I meant RTSP communicating using TCP but controlling a stream  
> distributed using UDP without RTP wrappings.

A [elementary] stream in UDP without RTP would miss necessary
information needed for assembling datapackets back in to a
[elementary] stream. Basically when you break up a [elementary]
stream into packets you need the following info to assemble it back

    a) Sequence number
    b) Presentation Time Stamp.
    c) Flags indicating whole and partials segments.

RTP is a transport container that allows you to assemble a
dissassembled stream.

Another solution is MPEG-2 TS.

What you might be asking for is RTSP (over TCP) for setting up
and controlling a streaming session with streams distributed
in MPEG-2 TS over UDP. But that is hardly very elegant nor the right
way to do it. And the RTSP-part of is is used to little else than
downloading a sdp file.

>>>I would like to get this running with
>>>the Kreatel and Amino settop boxes who cannot do RTSP/RTP.
>>That's not true - at least for the Amino set-top boxes.  They handle
>>RTSP-over-TCP just fine.  However, the stream that they receive
>>(*not* the RTSP control channel) is MPEG Transport over UDP (not RTP).
> Yes, the same is true for Kreatel.

So they don't really support RTSP then. They just have the cabaility to
decode MPEG-2 TS received on a given port. Correct ?

> Ok. I can verify that it does work with the kreatel stb's as well.  
> However, as you point out in the faq, trick play doesn't work in the  
> current edition of the library. Any chance of that patch becoming  
> available soon?

Are you saying that the Kreatel box speaks RTSP meaning that it
can talk to a rtsp server using the rtsp protocol setting up
a streaming session and execute a rtsp play, but just can convert
rtp packets into a [elementary] stream ?

Kind regards

Peter Maersk-Moller

-- 
+----------------------------------------------------------+
| Kabel-TV over Internettet   --   http://www.streamtv.dk/ |
+----------------------------------------------------------+