Write opencv frames into gstreamer rtsp server pipeline

[Michael MacIntosh]

Hello WisdomPill,

I would suggest checking out this example if you haven't done so already:

https://github.com/GStreamer/gst-rtsp-server/blob/master/examples/test-appsrc.c

It is in C and I apologize I am not familiar with the python interface.

Two things I notice is it doesn't look like you are setting the appsrc 
format to time.   By default it is bytes.  You can change that like this 
(C++):

gst_util_set_object_arg(G_OBJECT(video_appsrc),"format","time");

Since you are setting the PTS on the frames, you need to do this.  You 
might be getting invalid/unexpected format errors because of this.

I would also recommend setting up pushing frames on the 
"media-configured" signal on the media factory (assuming you are using a 
live source).  You can stop pushing frames when you get GST_FLOW_NOT_OK 
when you push your frames.

This way you can start pushing frames only when a client connects.  And 
stop pushing when they disconnect.

It also does not look like you are setting the caps on the appsrc.  I am 
fairly certain you need to do this.

You might also want to post what log output and what errors you are 
getting so people can better help you.

Good luck, appsrc rtsp servers are pretty challenging.

Cheers,
Michael.


On 11/20/2017 8:13 AM, WisdomPill wrote:
> I'm trying to put opencv images into a gstreamer rtsp server in python.
> I have some issue writing in the mediafactory, I'm new to gst-rtsp-server
> ancd there's little documentation so I don't know exactly if I'm using the
> right approach. I'm using a thread to start the MainLoop and I'm using the
> main thread to create a buffer to push in the appsrc element of the
> mediafactory pipeline. Am I using the right approach to obtain my objective?
> Can anyone help me? My code is below:
>
>      from threading import Thread
>      from time import clock
>      
>      import cv2
>      import gi
>      
>      gi.require_version('Gst', '1.0')
>      gi.require_version('GstRtspServer', '1.0')
>      from gi.repository import Gst, GstRtspServer, GObject
>      
>      
>      class SensorFactory(GstRtspServer.RTSPMediaFactory):
>          def __init__(self, **properties):
>              super(SensorFactory, self).__init__(**properties)
>              self.launch_string = 'appsrc !
> video/x-raw,width=320,height=240,framerate=30/1 ' \
>                                   '! videoconvert ! x264enc
> speed-preset=ultrafast tune=zerolatency ' \
>                                   '! rtph264pay config-interval=1 name=pay0
> pt=96'
>              self.pipeline = Gst.parse_launch(self.launch_string)
>              self.appsrc = self.pipeline.get_child_by_index(4)
>      
>          def do_create_element(self, url):
>              return self.pipeline
>      
>      
>      class GstServer(GstRtspServer.RTSPServer):
>          def __init__(self, **properties):
>              super(GstServer, self).__init__(**properties)
>              self.factory = SensorFactory()
>              self.factory.set_shared(True)
>              self.get_mount_points().add_factory("/test", self.factory)
>              self.attach(None)
>      
>      
>      GObject.threads_init()
>      Gst.init(None)
>      
>      server = GstServer()
>      
>      loop = GObject.MainLoop()
>      th = Thread(target=loop.run)
>      th.start()
>      
>      print('Thread started')
>      
>      cap = cv2.VideoCapture(0)
>      
>      print(cap.isOpened())
>      
>      frame_number = 0
>      
>      fps = 30
>      duration = 1 / fps
>      
>      timestamp = clock()
>      
>      while cap.isOpened():
>          ret, frame = cap.read()
>          if ret:
>      
>              print('Writing buffer')
>      
>              data = frame.tostring()
>      
>              buf = Gst.Buffer.new_allocate(None, len(data), None)
>              buf.fill(0, data)
>              buf.duration = fps
>              timestamp = clock() - timestamp
>              buf.pts = buf.dts = int(timestamp)
>              buf.offset = frame_number
>              frame_number += 1
>              retval = server.factory.appsrc.emit('push-buffer', buf)
>              print(retval)
>      
>              if cv2.waitKey(1) & 0xFF == ord('q'):
>                  break
>      
>      cap.release()
>
> By the way I tried to copy the buffer creation from opencv source code but
> I'm not sure I correctly trandlated the c++ code in python.
>
>
>
> --
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