Multiple Source Pipeline Hangs
Tim-Philipp Müller
t.i.m at zen.co.uk
Tue May 7 09:32:46 PDT 2013
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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