[gst-devel] Dynamic pipeline problem

[Stefan Kost]

hi,

I belive this needs some work in gnonlin too. Here is a documenta that explains:
http://webcvs.freedesktop.org/gstreamer/gstreamer/docs/design/part-block.txt?view=markup

Stefan


Dominique Würtz wrote:
> Hi,
> 
> in my GStreamer/GNonlin-based project (some multi-track audio application), I
> need to add/remove elements to/from the main pipeline while in PLAYING or PAUSED
> state. Until now this works quite unreliably and results in occasional
> freezes/crashes.
> 
> To give you an idea of how my pipeline works, I attached a Python script which
> runs a pipeline and constantly adds and removes "tracks" (which here correspond
> to gnonlin compositions). For me this works only for a few seconds. I guess
> there are some additional checks missing at various places in my code, but I
> have no clue where to find documentation about this. Can anybody help me to get
> my test script working flawlessly?
> 
> I'm using the latest Gstreamer/gst-plugins-base/gnonline releases.
> 
> Regards,
> 
> Dominique
> 
> 
> ------------------------------------------------------------------------
> 
> import pygst
> pygst.require("0.10") 
> import gst
> import gobject
> 
> class Track:
> 
>     def __init__(self, pipeline):
>         self.comp = gst.element_factory_make("gnlcomposition")
>         self.comp.connect("pad-added", self.on_composition_pad_added)
>         pipeline.add(self.comp)
>         self.comp.set_state(gst.STATE_PLAYING)
> 
>     def on_composition_pad_added(self, comp, pad):
>         caps = pad.get_caps()
>         self.srcpad = pad
>         if not comp.get_parent() or not convert.get_parent():
>             return
>         gst.Element.link(comp, adder)
> 
> def go():
>     global num_tracks, tracks, action
>     
>     if action == ACTION_ADD_TRACK:
>         print "Add Track"
>         tracks.append(Track(pipeline))
>         action = ACTION_ADD_EVENT
>     elif action == ACTION_ADD_EVENT:
>         print "Add Event"
> 
>         track = tracks[-1]
>         silence = gst.element_factory_make("audiotestsrc")
>         silence.set_property("wave", "silence")
>         src = gst.element_factory_make("gnlsource")
>         src.add(silence)
>         src.set_property("start", 0 * gst.SECOND)
>         src.set_property("duration", 1000 * gst.SECOND)
>         track.comp.add(src)
>         
>         if len(tracks) < 3:
>             action = ACTION_ADD_TRACK
>         else:
>             action = ACTION_REMOVE_TRACK
>     else:
>         print "Remove Track"
>         track = tracks.pop()
>         try:
>             sink = track.srcpad.get_peer()
>             gst.Element.unlink(track.comp, adder)
>             adder.release_request_pad(sink)
>         except:
>             pass
>         track.comp.set_state(gst.STATE_NULL)
>         pipeline.remove(track.comp)
>         if not tracks:
>             action = ACTION_ADD_TRACK
>     return True
> 
> adder = gst.element_factory_make("adder")
> convert = gst.element_factory_make("audioconvert")
> sink = gst.element_factory_make("alsasink")
> pipeline = gst.element_factory_make("pipeline")
> pipeline.add(adder, convert, sink)
> gst.Element.link(adder, convert)
> gst.Element.link(convert, sink)
> 
> ACTION_ADD_TRACK = 0
> ACTION_ADD_EVENT = 1
> ACTION_REMOVE_TRACK = 2
> action = ACTION_ADD_TRACK
> 
> tracks = []
> 
> gobject.threads_init()
> gobject.idle_add(go)
> pipeline.set_state(gst.STATE_PLAYING)
> gobject.MainLoop().run()
> pipeline.set_state(gst.STATE_NULL)
> 
> 
> ------------------------------------------------------------------------
> 
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