voctocore/experiments/startuptest/startuptest.py



#!/usr/bin/python3

# Example for the startup-problem
#
# The Pipeline will start but the test-image will be still, as long as no
# ShmSink at /tmp/grabber-v is present (run ../test-grabber-src.sh in another shell)
#
# Even though the ShmSrc is not linked to anything and logically not required for
# the videotestsrc or the ximagesink, the whole pipeline won't startup when this element
# fails to start.
#
# once the pipeline is running, it does not matter what happens to the ShmSink on the
# other end, because the TestBin filters all EOS and ERROR Messages coming from the ShmSrc,
# but somehow this is not enough to make the pipeline start in an error-condition..
#

import gi

# 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)

from testbin import TestBin

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

        self.src = Gst.ElementFactory.make('videotestsrc', None)
        self.sink = Gst.ElementFactory.make('ximagesink', None)

        self.testbin = TestBin()

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

        self.src.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()

    def on_eos(self, bus, msg):
        print('on_eos()')
        #self.kill()

    def on_error(self, bus, msg):
        print('on_error():', msg.parse_error())
        #self.kill()

example = Example()
example.run()