[vlc-devel] VLC RTSP Server Support for Keep-Alive Messages to Kill Orphaned Streams?

Robert Krakora rob.krakora at messagenetsystems.com
Wed Jul 15 23:21:52 CEST 2009

On Wed, Jul 15, 2009 at 4:16 PM, Robert
Krakora<rob.krakora at messagenetsystems.com> wrote:
> 2009/7/15 Rémi Denis-Courmont <remi at remlab.net>:
>> Le mercredi 15 juillet 2009 22:47:33 Robert Krakora, vous avez écrit :
>>> Again, thanks for the quick response.  May I inquire how then does the
>>> VLC RTSP server handle orphaned RTSP sessions?
>> RTSP sessions are not such a big deal. They just time out via normal TCP
>> transport semantics. Similarly RTP over DCCP will time out through congestion
>> control. RTP over UDP is never timing out, and that is a problem.
>>> How about a command line and GUI option that allows the minimum
>>> "keep-alive" functionality described in the RFC to be utilized (i.e.
>>> GET_PARAMETER and PLAY).  Of course the RTSP server would also have to
>>> convey the "keep-alive" timeout to the RTSP clients so that they know
>>> to send "keep-alives" and at what interval to send them.
>> No. IIRC, the keep-alive has a default value, and I see no strong reason to
>> not follow the default, but that's not the real problem.
>>> Surprise
>>> removal of RTSP clients without TEARDOWNs being issued happens all the
>>> time with settop boxes in situations where they lose power (unplugged
>>> for instance) or are reset by users.
>> There is no "theoretical" problem. VLC just needs to reset the (would-be)
>> timer when _either_ an RTSP request comes _or_ a valid RTCP-RR is received.
>> When the timer fires, the RTP stream is dropped. Nobody has ever bothered to
>> implement this.
>> --
>> Rémi Denis-Courmont
>> http://www.remlab.net/
>> _______________________________________________
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> Remi:
> RTP over UDP is what I am utilizing.  I am going to look into
> implementing this as I need this feature if there are no objections.
> Best Regards,
> --
> Rob Krakora
> Senior Software Engineer
> MessageNet Systems
> 101 East Carmel Dr. Suite 105
> Carmel, IN 46032
> (317)566-1677 Ext. 206
> (317)663-0808 Fax


When I build VLC I specify a path to the latest Live RTSP source that
I have on my system.  I was under the assumption that VLC would
utilize both Live's RTSP server and client instead of those resident
in the VLC source.  However, it looks like this is only true in the
case of the RTSP client.  The Live RTSP server already employs the
RTSP "keep-alive" implementation that you proposed via most recent
RTSP request and RTCP-RR.  How hard would it be to modify VLC to
utilize both the current RTSP server in the VLC source or the Live
RTSP server?

Best Regards,

Rob Krakora
Senior Software Engineer
MessageNet Systems
101 East Carmel Dr. Suite 105
Carmel, IN 46032
(317)566-1677 Ext. 206
(317)663-0808 Fax

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