[vlc-devel] Help about GET_PARAMETERS

Rémi Denis-Courmont remi at remlab.net
Thu Jun 9 13:40:51 CEST 2011

On Thu, 9 Jun 2011 11:51:46 +0100, Glen Gray <slaine at slaine.org> wrote:
> The GET_PARAMETERS should only trigger if the RTSP SETUP response
> a timeout value. If a timeout is there, VLC will send an empty
> GET_PARAMETERS message as a keep alive method for the stream. Say for
> example you paused the stream for > timeout, you don't want the session
> torn down. There are other methods for doing keep alive, like RTCP "RR"
> messages.

RFC2326 specifies a default timeout of 60 seconds. As far as I know, an
RTSP session always has a timeout, and an RTSP client must act accordingly.
Some buggy servers (like old VLC versions) do not implement the timeout,
but an RTSP client cannot rely on that property.

VLC will use GET_PARAMETERS if the OPTIONS response permits. If not, then
VLC will not actively ping the server: it implicitly assumes that RTCP-RR
packets are enough to keep the session alive, for lack of an alternative.

Rémi Denis-Courmont

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