Multiple Source Pipeline Hangs

johnwesting john.blank.westing at gmail.com
Tue May 7 09:37:14 PDT 2013


It's not only before, source 2 will not even start to negotiate its caps
until source 1 is completely finished negotiating.


On Tue, May 7, 2013 at 12:34 PM, Tim-Philipp Müller-2 [via GStreamer-devel]
<ml-node+s966125n4659824h1 at n4.nabble.com> wrote:

> On Tue, 2013-05-07 at 08:58 -0700, johnwesting wrote:
>
> > I placed queues, queue2s, and multiqueues in every place the pipeline
> > would allow. I guess there's no hope for starting both sources in
> > parallel using gst-launch?
>
> I assume both sources operate in push mode, in which case a streaming
> thread will be started for each. They will run independent of each other
> by default already. If you observe that caps for source1 are negotiated
> before source2 starts up, that's most likely a coincidence, or something
> timing-related on your specific machine.
>
>  Cheers
>   -Tim
>
>
> > On Tue, May 7, 2013 at 11:07 AM, Tim-Philipp Müller-2 [via
> > GStreamer-devel] <[hidden email]> wrote:
> >         On Tue, 2013-05-07 at 07:09 -0700, johnwesting wrote:
> >
> >
> >         > I'm not sure where I got this from but I thought with
> >         GStreamer
> >         > versions 0.8 is less than 0.10, does that mean the threading
> >         feature
> >         > was removed from newer versions? Why?
> >         >
> >         >
> >         > If I don't have the option of creating threads using the {}
> >         brackets
> >         > then how can I spawn additional threads using gst-launch? I
> >         tried
> >         > placing queues everywhere I could in the pipeline but this
> >         still did
> >         > not solve the problem.
> >
> >
> >         In 0.10 and 1.0 you can force the creation of a new streaming
> >         thread by
> >         inserting a queue (or multiqueue) element into the pipeline.
> >
> >         In 0.8 scheduling (when data would flow between which pads)
> >         worked
> >         completely differently, there were dedicated schedulers which
> >         would try
> >         to figure out which pads needed attention etc. In 0.10/1.0 we
> >         leave this
> >         kind of scheduling mostly to the kernel.
> >
> >          Cheers
> >           -Tim
> >
> >
> >         >
> >         > On Tue, May 7, 2013 at 6:18 AM, Tim-Philipp Müller-2 [via
> >
> >         > GStreamer-devel] <[hidden email]> wrote:
> >
> >         >         On Tue, 2013-05-07 at 08:50 +0100, David
> >         Röthlisberger wrote:
> >         >
> >         >         > On 6 May 2013, at 21:50, John Westing wrote:
> >         >         > >
> >         >         > > I read the article and understand that the
> >         problem is
> >         >         likely an issue with threading, hence the reason for
> >         the {}
> >         >         brackets described in my first post: {} brackets in
> >         a
> >         >         gst-launch pipeline spawn an additional thread for
> >         the
> >         >         elements surrounded in the brackets. However, in my
> >         case when
> >         >         I use the {} brackets I get the GStreamer warning
> >         "Error
> >         >         during parsing: syntax error, unexpected $undefined"
> >         as
> >         >         described in my first post.
> >         >         >
> >         >         > Interesting, I didn't know that! Where is this
> >         documented? A
> >         >         Google
> >         >         > search for "gst-launch brackets thread" returns
> >         this man
> >         >         page:
> >         >         >
> >         http://linux.about.com/library/cmd/blcmdl1_gst-launch.htm
> >         >         >
> >         >         > which says:
> >         >         >
> >         >         >     A group of elements surrounded by curly braces
> >         {, } will
> >         >         be executed
> >         >         >     in a separate thread.
> >         >         >
> >         >         > However, it isn't clear what version of GStreamer
> >         the above
> >         >         corresponds
> >         >         > to. On my Ubuntu 12.10 system, neither the man
> >         page for
> >         >         gst-launch-0.10
> >         >         > nor gst-launch-1.0 contain this text (nor any
> >         mention of
> >         >         "{").
> >         >         That { } syntax for a new thread is GStreamer 0.8
> >         syntax. It
> >         >         doesn't do
> >         >         anything in 0.10.x or 1.x. It's probably best to
> >         ignore every
> >         >         document
> >         >         where you find these in a gst-launch context.
> >         >
> >         >         Cheers
> >         >          -Tim
> >         >
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