Restart pipeline with Python on Error

[jack]

I forgot, my configuration :
Ubuntu 20.04
GStreamer 1.16.2


I expected using pipeline.set_state(Gst.State.NULL) followed
by pipeline.set_state(Gst.State.PLAYING) will be enough to restart my
pipeline. But I am wrong.
If someone can explain what to do it would be very much appreciated !
A link would be nice. I can't find an example on the web about this
subject (for Python).
Best!
++

Jack



Le dimanche 17 juillet 2022 à 21:24 +0200, jack via gstreamer-devel a
écrit :
> Hello !
> 
> I would like to restart a very simple pipeline on error using Python.
> I tried but I failed.
> 
> My pipeline :
> 
> pipeline = Gst.parse_launch('souphttpsrc name=toto location=
> http://stream.p-node.org/billiejean.mp3 ! '
>                             'decodebin ! '
>                             'audioconvert ! '
>                             'audioresample ! '
>                             'autoaudiosink')
> 
> 
> My fist attempt was :
> 
> bus.connect("sync-message::error", _on_sync_bus_message_error)
> def _on_sync_bus_message_error(bus, message):
>     print(f'Error for stream', bus, message)
>     print('Restarting')
>     pipeline.set_state(Gst.State.NULL)
>     pipeline.set_state(Gst.State.PLAYING)
> 
> Then i get :
> 
> (python:903853): GStreamer-WARNING **: 21:07:57.021: 
> Trying to join task 0x166a290 from its thread would deadlock.
> You cannot change the state of an element from its streaming
> thread. Use g_idle_add() or post a GstMessage on the bus to
> schedule the state change from the main thread.
> 
> 
> OK, so let's go with "post a GstMessage on the bus to
> schedule the state change from the main thread"
> 
> Here my second attempt :
> 
> bus.connect("sync-message::error", _on_sync_bus_message_error)
> def _on_sync_bus_message_error(bus, message):
>     print(f'Error for stream', bus, message)
>     print('Restarting')
>     custom_structure = Gst.Structure.new_empty("iserror")
>     custom_message = Gst.Message.new_application(None,
> custom_structure)
>     bus.post(custom_message)  # here i post message on the bus...
> 
> 
> Then I have a loop while to get message on the bus :
> 
> while True:
>     try:
>         message = bus.timed_pop(Gst.SECOND)
>         if message == None:
>             pass
>         elif message.type == Gst.MessageType.APPLICATION:
>             if message.get_structure().get_name() == "iserror":
>                 print('There is an error...')
>                 pipeline.set_state(Gst.State.NULL)
>                 pipeline.set_state(Gst.State.PLAYING)
>     except KeyboardInterrupt:
>         break
> 
> I was expecting to have my pipeline to restart but unfortnutely it
> didn't.
> 
> What is the next step to to restart my pipeline ?
> Best!
> ++
> 
> Jack
> 
> 
>