path: root/voctocore/experiments/sync-videomix.py

#!/usr/bin/python3
import gi, time
import socket

# import GStreamer and GTK-Helper classes
gi.require_version('Gst', '1.0')
from gi.repository import GLib, Gst, GObject

# init GObject before importing local classes
GObject.threads_init()
Gst.init(None)

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

        pipeline = """
            videotestsrc pattern=red !
            {caps} !
            mix.

            videotestsrc pattern=green !
            {caps} !
            mix.

            compositor name=mix !
            {caps} !
            identity name=sig !
            videoconvert !
            pngenc !
            multifilesink location=frame%04d.png
        """.format(
            caps='video/x-raw,width=800,height=450,format=I420,framerate=25/1'
        )

        self.pipeline = Gst.parse_launch(pipeline)

        # with sync=False changes to videomixer & scaler are performed
        # from the main thread. In the frame-images it becomes clear, that
        # sometimes not all changes are applied before a frame is pushed
        # through the mixer, and so there are "half modified" frames where
        # some pieces are missing, the zorder or the size of one video is
        # incorrect
        # with sync=True all changes are made from the streaming-thread
        # that drives the videomixer and the following elements, so they
        # are always completed before the mixer processes the next frame
        sync = True
        if sync:
            sig = self.pipeline.get_by_name('sig')
            sig.connect('handoff', self.reconfigure)
        else:
            GLib.timeout_add(1/25 * 1000, self.reconfigure, 0, 0)

        self.pad0 = self.pipeline.get_by_name('mix').get_static_pad('sink_0')
        self.pad1 = self.pipeline.get_by_name('mix').get_static_pad('sink_1')

        self.state = False

    def reconfigure(self, object, buffer):
        print("reconfigure!")
        if self.state:
            padA = self.pad0
            padB = self.pad1
        else:
            padA = self.pad1
            padB = self.pad0

        padA.set_property('xpos', 10)
        padA.set_property('ypos', 10)
        padA.set_property('alpha', 1.0)
        padA.set_property('zorder', 1)
        padA.set_property('width', 0)
        padA.set_property('height', 0)

        padB.set_property('xpos', 310)
        padB.set_property('ypos', 170)
        padB.set_property('alpha', 1.0)
        padB.set_property('zorder', 2)
        padB.set_property('width', 480)
        padB.set_property('height', 270)

        self.state = not self.state
        return True

    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()