[Live-devel] RTSP UDP multicast Streams and RTP video and audio on the same port

[Brent Hunsaker]

Thank you for your reply.  I have been testing and stepping through the 
openRTSP code.  I have included verbose output that I have received from 
my openRTSP session.  I do have a couple more questions.

I am working with an MPEG 2 Transport stream that I am streaming with 
our RTSP Streamer.  It does successfully stream and record both and 
audio and video streams (although the 2 streams include both audio and 
video).  How do I get the client to not expect separate streams?  Please 
look at the log and let me know if you see anything strange.  I am 
confused about the interpretation of the SDP that is returned in 
response to the client's DESCRIBE command.  In our server we use:

m=video 5012 udp 33
m=audio 5012 udp 33

where 33 is the RTP Payload Type MP2T.  Since it is not an RTP Payload 
Type shouldn't this field be ignored?  I have also tried 0 instead of 33 
(PCMU) but they both appear to behave the same.  Originally I tried a 
port of 5011 and the live library would create an RTP/RTCP pair of 
5010-5011 where 5010 is the stream port.  This causes a problem because 
the actual stream comes over 5011 and not 5010 (the RTCP port if we were 
using RTP/AVP).  Does this mean that I can't use an odd numbered port 
even though I am using udp and not rtp?  I looked in the source and it 
doesn't seem to care what the protocol is and always assumes a separated 
stream as evidenced by the separate video and audio files that are 
recorded when openRTSP is run.

I've also noticed that the MIME formats for M1S and M2P are not 
available under the RTP Payload Type.  Does that mean that they can't be 
sent via RTP/AVP?

Thanks for your help.

Brent Hunsaker

Ross Finlayson wrote:

> At 03:44 PM 9/9/2005, you wrote:
>
>> I have been using the 0.8.2 version of VLC for Windows.  I have been 
>> trying to get this VLC client which uses your RTSP library to 
>> properly communicate with our RTSP Server so that I can use RTSP to 
>> start UDP multicast streams.  The VLC client will start the stream OK 
>> but it can't play the video and eventually crashes.
>>
>> It seems that this only works using VOD unicast RTP streams.  I have 
>> successfully run the VLC Server and Client on different machines and 
>> gotten a VOD stream.  However changing the output from vod to 
>> broadcast does not seem to work either.  Is this by design or am I 
>> missing something?
>
>
> As I don't know anything about your server, I can't help you much 
> here.  But as I noted yesterday in response to someone else's 
> question, it's up to the server to decide - based on the RTSP URL - 
> whether the stream is multicast or unicast.
>
> In any case, I suggest that you use the "openRTSP" command-line client 
> - rather than VLC - to debug your server.  See 
> <http://www.live.com/openRTSP/>.  If you give "openRTSP" the "-V" 
> option, you will see the full RTSP protocol exchange.
>
>> Also I am wanting to stream video and audio on the same port.  I read 
>> in the FAQ that separating the streams is by design.  Does that mean 
>> that the library only works with separate streams and that combining 
>> them under RTSP is not possible?
>
>
> No, once again this is something that's up to the server to decide.  
> However, most RTSP servers send separate RTP streams - on separate 
> port numbers - for audio and video.  The main exception is servers 
> that send MPEG Transport Streams (which contain audio and video 
> multiplexed together in a single stream).
>
>
>     Ross Finlayson
>     Live Networks, Inc. (LIVE.COM)
>     <http://www.live.com/>
>
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