gstreamer appsrc causes random crashes

Question

I'm trying to setup a GStreamer appsrc as a video source, but even a trivial program does not work at all and produces random crashes or hangings so far. Could you please help to spot the problem? Minimal crashing code:

import gst, gtk

def need_data(src, need_bytes):
    src.emit("push-buffer", gst.Buffer(" "*need_bytes))

def on_message(bus, msg):
    print "on_message", msg

pipeline = gst.parse_launch("appsrc name=src ! fakesink")

src = pipeline.get_by_name("src")
src.connect("need-data", need_data)
src.set_property("blocksize", 640*480*3)

bus = pipeline.get_bus()
bus.add_signal_watch()
bus.connect("message", on_message)

pipeline.set_state(gst.STATE_PLAYING)
gtk.main()

Answer 1

The solution appeared to be quite simple. At some point program was lucky to spit Fatal Python error: GC object already tracked message, and it became pretty clear: a call to gobject.threads_init() was missing. Adding this call to the beginning of the program fixed the issue.

Answer 2

You can use gst-debug-level to probe further into the problem.

Lets say your code is in the file gst-test.py.

Launch it like this:

python gst-test.py --gst-debug-level=3

This will give you a better idea about whats going on. Try changing the value from 3 to 1 to lower the noise.

My gut feeling is that you are missing the caps. You'll also probably have to set the props too.

Answer 3

I've run into this issue 'GC object already tracked' and did try adding the code gobject.threads_init() but it still did not fix the issue.

There were couple of suggestions in below article to diagnose this issue. Hope that helps. Python memory debugging with GDB