Can not trigger "on-receiving-rtcp" event to get RTCP packet

Wed May 31 04:55:40 UTC 2023

I just follow the code in the article.
Anyway it turns out the server did not send and rtcp message, I wireshark
the communication between client and server.
So the code works.
Thanks😁

On Tue, 23 May 2023 at 6:26 PM, Mathieu Duponchelle <mathieu at centricular.com>
wrote:

> Why are you requesting the pad in the first place?
>
> On Sun, 2023-05-21 at 15:27 +0800, Max Weng via gstreamer-devel wrote:
> > Hi,
> >
> >     I am currently exploring the possibilities of using GStreamer for
> > a project, a territory that is relatively new to me. I am convinced,
> > however, that GStreamer is an ideal fit for my objectives.
> >
> > The task at hand is to extract server timestamps from RTCP packets.
> > For this, I referred to the article, Absolute Timestamp of Arbitrary
> > Frame in RTSP Stream with GStreamer
> >
> >   I have been running into some difficulties during the
> > implementation phase.
> >
> > I am experiencing an inconsistent triggering of the "on-receiving-
> > rtcp" event. It appears to get activated only sporadically,
> > approximately once in every 20 attempts. This inconsistency makes it
> > challenging for me to proceed effectively with the project.
> >
> > In addition, an error message always presents itself: "Element
> > manager already has a pad named recv_rtcp_sink_0, the behaviour of
> > gst_element_get_request_pad() for existing pads is undefined!". This
> > error is making the situation even more complex to understand and
> > resolve.
> >
> > I would truly appreciate it if you could provide some insights or
> > suggestions regarding these issues. I am eager to understand what
> > might be causing these problems, and how best to address them.
> >
> >   here is my code test_gstreamer.py:
> >
> > import datetime
> > import pickle
> > from multiprocessing.connection import Connection
> > import threading
> >
> > from time import sleep
> > import gi
> > from log import setup_custom_logger
> >
> > gi.require_version("Gst", "1.0")
> > gi.require_version("GstRtp", "1.0")
> > gi.require_version("GstVideo", "1.0")
> >
> > from gi.repository import GLib, GObject, Gst, GstRtp, GstVideo #
> > noqa:F401,E402
> >
> > logger = setup_custom_logger(__name__)
> >
> > GObject.threads_init()
> > Gst.init()
> >
> > url = 'rtsp://localhost:8554/mystream'
> > pipeline = ''
> >
> >
> > def fly():
> >  main_loop = GLib.MainLoop()
> >  main_loop_thread = threading.Thread(target=main_loop.run)
> >  main_loop_thread.start()
> >  command = f"rtspsrc name=rtspsrc location={url} protocols=tcp
> > latency=10 max-rtcp-rtp-time-diff=10 ! errorignore ! rtph265depay
> > name=depay ! appsink name=sink"
> >  pipeline = Gst.parse_launch(command)
> >  bus = pipeline.get_bus()
> >  bus.add_signal_watch()
> >  bus.connect("message", on_message)
> >  bus.enable_sync_message_emission()
> >
> >  rtspsrc = pipeline.get_by_name("rtspsrc")
> >  rtspsrc.connect("new-manager", on_new_manager)
> >  depay = pipeline.get_by_name("depay")
> >  sinkpad = depay.get_static_pad("sink")
> >  probeID = sinkpad.add_probe(
> >  Gst.PadProbeType.BUFFER, calculate_timestamp)
> >
> >  pipeline.set_state(Gst.State.PLAYING)
> >
> >  try:
> >  while True:
> >  sleep(0.1)
> >  except KeyboardInterrupt:
> >  pass
> >
> >  pipeline.set_state(Gst.State.NULL)
> >  main_loop.quit()
> >  main_loop_thread.join()
> >
> >
> > def calculate_timestamp(pad, info):
> >  return Gst.PadProbeReturn.OK
> >
> >
> > def on_new_manager(rtspsrc, manager):
> >  logger.info(f"on_new_manager")
> >  sinkpad = manager.get_request_pad("recv_rtcp_sink_0")
> >  session = manager.emit("get-internal-session", 0)
> >  session.connect("on-receiving-rtcp", on_receive_rtcp)
> >
> >
> > def on_receive_rtcp(session, buffer: Gst.Buffer):
> >  logger.info("on_receive_rtcp")
> >  logger.info(buffer)
> >  rtcp_buffer = GstRtp.RTCPBuffer()
> >  res = GstRtp.RTCPBuffer.map(buffer, Gst.MapFlags.READ, rtcp_buffer)
> >  rtcp_packet = GstRtp.RTCPPacket()
> >  rtcp_buffer.get_first_packet(rtcp_packet)
> >
> >  while True:
> >  if rtcp_packet.get_type() == GstRtp.RTCPType.SR:
> >  logger.info(rtcp_packet)
> >  si = rtcp_packet.sr_get_sender_info()
> >  ntp_time = si[1]
> >  rtp_time = si[2]
> >  logger.info("ntp_time: %d, rtp_time: %d", ntp_time, rtp_time)
> >  if rtcp_packet.move_to_next() == False:
> >  break
> >
> >
> > def on_message(bus: Gst.Bus, message: Gst.Message):
> >  mtype = message.type
> >  # TODO handle message
> >
> >
> > if __name__ == "__main__":
> >  fly()
> >
> >
> > here is how I run a local RSTP server:
> > $ docker run --rm -it --network=host aler9/rtsp-simple-server
> > $ while true; do gst-launch-1.0 rtspclientsink name=s
> > location=rtsp://localhost:8554/mystream
> >  filesrc location=//path/to/video.mp4
> >  ! qtdemux name=d d.video_0 ! queue ! s.sink_0 d.audio_0 ! queue !
> > s.sink_1 ; done
> >
> > here is the output from my code, no "on-receiving-rtcp" triggered:
> > $ python test_gstreamer.py
> > test_gstreamer.py:19: PyGIDeprecationWarning: Since version 3.11,
> > calling threads_init is no longer needed. See:
> > https://wiki.gnome.org/PyGObject/Threading
> >   GObject.threads_init()
> > 2023-05-21 15:05:06,467 - __main__ - INFO - on_new_manager
> >
> > (python:96503): GStreamer-CRITICAL **: 15:05:06.469: Element manager
> > already has a pad named recv_rtcp_sink_0, the behaviour of
> >  gst_element_get_request_pad() for existing pads is undefined!
> >
> > here is output with "on-receiving-rtcp" triggered:
> > $ python test_gstreamer.py
> > test_gstreamer.py:19: PyGIDeprecationWarning: Since version 3.11,
> > calling threads_init is no longer needed. See:
> > https://wiki.gnome.org/PyGObject/Threading
> >   GObject.threads_init()
> > 2023-05-21 15:05:10,382 - __main__ - INFO - on_new_manager
> >
> > (python:96548): GStreamer-CRITICAL **: 15:05:10.384: Element manager
> > already has a pad named recv_rtcp_sink_0, the behaviour of
> > gst_element_get_request_pad() for existing pads is undefined!
> > 2023-05-21 15:05:11,730 - __main__ - INFO - on_receive_rtcp
> > 2023-05-21 15:05:11,730 - __main__ - INFO - <Gst.Buffer object at
> > 0x7fbf3a6918e0 (GstBuffer at 0x166cc60)>
> > 2023-05-21 15:05:11,732 - __main__ - INFO - <GstRtp.RTCPPacket object
> > at 0x7fbf39c49860 (void at 0x7fbf2c08b390)>
> > 2023-05-21 15:05:11,732 - __main__ - INFO - ntp_time:
> > 16723062952823484284, rtp_time: 4125066893
> >
>
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