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79 lines
2.5 KiB
Python
79 lines
2.5 KiB
Python
#!/usr/bin/python
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# Shows how two test sources can be mixed together.
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#
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# A variation of what's on
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# https://stackoverflow.com/questions/3899666/adding-and-removing-audio-sources-to-from-gstreamer-pipeline-on-the-go
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import os
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import gi
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gi.require_version('Gst', '1.0')
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gi.require_version('Gtk', '3.0')
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from gi.repository import Gst, GObject, Gtk
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Gst.init(None)
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GObject.threads_init()
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# def buzzersrc1_probe_callback(a,b):
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# print("buzzersrc1_probe_callback called")
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if __name__ == "__main__":
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# First create our pipeline
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pipe = Gst.Pipeline.new("mypipe")
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audiomixer = Gst.ElementFactory.make("audiomixer","audiomixer")
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pipe.add(audiomixer)
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# Gather a request sink pad on the mixer
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sinkpad1=audiomixer.get_request_pad("sink_%u")
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print("sinkpad1:" + str(sinkpad1))
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# Create the first buzzer..
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buzzer1 = Gst.ElementFactory.make("audiotestsrc","buzzer1")
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buzzer1.set_property("freq",1000)
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pipe.add(buzzer1)
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# .. and connect it's source pad to the previously gathered request pad
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buzzersrc1=buzzer1.get_static_pad("src")
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buzzersrc1.link(sinkpad1)
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# Add some output
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output = Gst.ElementFactory.make("autoaudiosink", "audio_out")
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pipe.add(output)
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audiomixer.link(output)
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# Start the playback
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pipe.set_state(Gst.State.PLAYING)
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input("1kHz test sound. Press <ENTER> to continue.")
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# Get an another request sink pad on the mixer
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sinkpad2=audiomixer.get_request_pad("sink_%u")
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# Create an another buzzer and connect it the same way
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buzzer2 = Gst.ElementFactory.make("audiotestsrc","buzzer2")
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buzzer2.set_property("freq",500)
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pipe.add(buzzer2)
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buzzersrc2=buzzer2.get_static_pad("src")
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buzzersrc2.link(sinkpad2)
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# Start the second buzzer (other ways streaming stops because of starvation)
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buzzer2.set_state(Gst.State.PLAYING)
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input("1kHz + 500Hz test sound playing simoultenously. Press <ENTER> to continue.")
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# Before removing a source, we must use pad blocking to prevent state changes
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# buzzersrc1.set_blocked(True)
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# I think this gets replaced with:
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# buzzersrc1.add_probe(Gst.PadProbeType.BLOCK_DOWNSTREAM, buzzersrc1_probe_callback)
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# but it doesn't seem to be required.
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# Stop the first buzzer
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buzzer1.set_state(Gst.State.NULL)
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# Unlink from the mixer
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buzzersrc1.unlink(sinkpad2)
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# Release the mixers first sink pad
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audiomixer.release_request_pad(sinkpad1)
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# Because here none of the audiomixer's sink pads block, streaming continues
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input("Only 500Hz test sound. Press <ENTER> to stop.")
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