path: root/voctocore/experiments/binlinktest.py

#!/usr/bin/python3
import gi, time

gi.require_version('Gst', '1.0')
from gi.repository import GLib, Gst, GObject

GObject.threads_init()
Gst.init(None)

class SrcBin(Gst.Bin):
    def __init__(self):
        super().__init__()
        self.src = Gst.ElementFactory.make('videotestsrc', 'src')
        self.add(self.src)

        self.add_pad(
            Gst.GhostPad.new('src', self.src.get_static_pad('src'))
        )

class SinkBin(Gst.Bin):
    def __init__(self):
        super().__init__()
        self.sink = Gst.ElementFactory.make('autovideosink', 'sink')
        self.add(self.sink)

        self.add_pad(
            Gst.GhostPad.new('sink', self.sink.get_static_pad('sink'))
        )

class MixBin(Gst.Bin):
    def __init__(self):
        super().__init__()
        self.mix = Gst.ElementFactory.make('videomixer', 'src')
        self.add(self.mix)

        self.add_pad(
            Gst.GhostPad.new('src', self.mix.get_static_pad('src'))
        )

    def create_ghostpad(self, pad):
        ghostpad = Gst.GhostPad.new(pad.get_name(), pad)
        self.add_pad(ghostpad)
        return ghostpad

    def add_src(self, src):
        sinkpad = self.mix.get_request_pad('sink_%u')
        sinkpad.set_property('alpha', 0.75)
        srcpad = src.get_static_pad('src')

        # works
        #print(src.link(self.mix)) # True

        # doesn't
        #print(srcpad.link(sinkpad)) # Error => GST_PAD_LINK_WRONG_HIERARCHY

        # but this does
        sinkghostpad = self.create_ghostpad(sinkpad)
        print(srcpad.link(sinkghostpad)) # True

class Example:
    def __init__(self):
        self.mainloop = GObject.MainLoop()
        self.pipeline = Gst.Pipeline()

        self.src = SrcBin()
        self.sink = SinkBin()
        self.mix = MixBin()

        # Add elements to pipeline
        self.pipeline.add(self.src)
        self.pipeline.add(self.sink)
        self.pipeline.add(self.mix)

        self.mix.add_src(self.src)
        self.mix.link(self.sink)

    def run(self):
        self.pipeline.set_state(Gst.State.PLAYING)
        self.mainloop.run()

    def kill(self):
        self.pipeline.set_state(Gst.State.NULL)
        self.mainloop.quit()

example = Example()
example.run()