Strange behaviour

[jouke hijlkema]

Hello all,

First of all a big thank you for developing such a great tool !

That being said ... I have a problem with the following. On a remote machine I have an audio source with a udpsink on my local machine using port 8001

using :

gst-launch-1.0 -ev udpsrc port=8001 caps=application/x-rtp,media=audio,clock-rate=90000,encoding-name=MPA,payload=14,ssrc=2608690421,timestamp-offset=3965000461,seqnum-offset=25383 ! decodebin ! autoaudiosink

works perfectly and sound flows out of the speakers.

Using the following python code yields nothing, no errors but no sound either

import gi
gi.require_version('Gst', '1.0')
gi.require_version('GstVideo', '1.0')
from gi.repository import GObject, Gst, GstVideo
GObject.threads_init()
Gst.init(None)

self.pipeline = Gst.Pipeline("audioPipeline")
self.src      = Gst.ElementFactory.make("udpsrc","src")
self.dec      = Gst.ElementFactory.make("decodebin","dec")
self.sink     = Gst.ElementFactory.make("autoaudiosink","sink")

self.src.set_property("port",self.portIn)
self.src.set_property("caps",Gst.Caps.from_string("application/x-rtp,media=audio,clock-rate=90000,encoding-name=MPA,payload=14,ssrc=2608690421,timestamp-offset=3965000461,seqnum-offset=25383"))

self.pipeline.add(self.src,self.dec,self.sink)

self.src.link(self.dec)
self.dec.link(self.sink)

self.pipeline.set_state(Gst.State.PLAYING)

The question is thus, what am I doing wrong ?

Thanks in advance for your help

Jouke

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[Holger]

I think you know it, but just to be sure... Do you wait after calling self.pipeline.set_state(Gst.State.PLAYING)? This is not a blocking call and the program will exit immediately.

[Arjen Veenhuizen]

Couple of things:
1. decodebin has 'sometimes' src pads so you should not hard link decodebin to any element a-priori.
2. You have to connect to the 'pad-added' signal on decodebin and in its callback connect the remainder of your pipeline elements. (e.g. self.dec.connect("pad-added", self.cbDecPadAdded))
3. You need an event loop (e.g. GObject.Mainloop.run()) after you set the pipeline to PLAYING.