I am trying to go through the Gstreamer tutorial, but I got stuck on the first two already (1st, 2nd). Here is the copy of the 2nd lesson's code, for reference:
#!/usr/bin/env python3
import sys
import gi
import logging
gi.require_version("GLib", "2.0")
gi.require_version("GObject", "2.0")
gi.require_version("Gst", "1.0")
from gi.repository import Gst, GLib, GObject
logging.basicConfig(level=logging.DEBUG, format="[%(name)s] [%(levelname)8s] - %(message)s")
logger = logging.getLogger(__name__)
# Initialize GStreamer
Gst.init(sys.argv[1:])
# Create the elements
source = Gst.ElementFactory.make("videotestsrc", "source")
sink = Gst.ElementFactory.make("autovideosink", "sink")
# Create the empty pipeline
pipeline = Gst.Pipeline.new("test-pipeline")
if not pipeline or not source or not sink:
logger.error("Not all elements could be created.")
sys.exit(1)
# Build the pipeline
pipeline.add(source, sink)
if not source.link(sink):
logger.error("Elements could not be linked.")
sys.exit(1)
# Modify the source's properties
source.props.pattern = 0
# Can alternatively be done using `source.set_property("pattern",0)`
# or using `Gst.util_set_object_arg(source, "pattern", 0)`
# Start playing
ret = pipeline.set_state(Gst.State.PLAYING)
if ret == Gst.StateChangeReturn.FAILURE:
logger.error("Unable to set the pipeline to the playing state.")
sys.exit(1)
# Wait for EOS or error
bus = pipeline.get_bus()
msg = bus.timed_pop_filtered(Gst.CLOCK_TIME_NONE, Gst.MessageType.ERROR | Gst.MessageType.EOS)
# Parse message
if msg:
if msg.type == Gst.MessageType.ERROR:
err, debug_info = msg.parse_error()
logger.error(f"Error received from element {msg.src.get_name()}: {err.message}")
logger.error(f"Debugging information: {debug_info if debug_info else 'none'}")
elif msg.type == Gst.MessageType.EOS:
logger.info("End-Of-Stream reached.")
else:
# This should not happen as we only asked for ERRORs and EOS
logger.error("Unexpected message received.")
pipeline.set_state(Gst.State.NULL)
If I run this code, the Python's rocket icon starts jumping on the Dock, but no video is shown. If I launch it with GST_DEBUG=5 python3 02.py, I can see the things happening and time ticking, just no video output.
When I run the 1st lesson's code, which creates a playbin, there is no Python rocket on the Dock; I hear the audio playing, but again, no video.
If I change the 2nd lesson's code (copied above) and make the videotestsrc and autovideosink into audiotestsrc and autoaudiosink (and comment out the pattern parameter), again, it works — I can hear the beep.
The Gstreamer command line tools work correctly, showing a video window for the equivalent pipelines:
gst-launch-1.0 playbin uri=https://gstreamer.freedesktop.org/data/media/sintel_trailer-480p.webm
gst-launch-1.0 videotestsrc pattern=0 ! autovideosink
Any ideas why the Python version does not work correctly?
I have installed Gstreamer using brew install gstreamer (version: stable 1.22.2 (bottled), HEAD), with Python 3.11.3, on Mac OS Ventura 13.2.1 (22D68).
