How to create one pipeline for both audio-video stream and only video stream.

[Алексей Буров]

Hello, all.
I have a rtsp source and I need to restream it through my rtsp server. 
The rtsp source can stream audio/video and sometimes only video.

I can create either audio/video pipeline or only video pipeline.
But I can't create working pipeline for these both cases.

I connect callback to 'pad-added' event and then I link the first video element and the first audio element (if audio exists) to rtspsrc  element in 'pad-added' callback.
I create/add/link audio elements in 'pad-added' callback but the rtsp client has no audio in this case.

Please tell me what is wrong.


This pipeline works well with audio-video: 

Gst.parse_launch(
    '( rtspsrc location="rtsp://admin:admin@192.168.7.217" '
        'latency=0 '
        'timeout=5000000 '
        'name=rtsp_src '
    'rtsp_src. '
        '! queue'
        '! rtph264depay '
        '! rtph264pay '
            'name=pay0 '
    'rtsp_src. '
        '! queue'
        '! rtppcmudepay '
        '! rtppcmupay '
            'name=pay1 )'
)

OS: gentoo, gstreamer: version 1.6.3, gst-rtsp-server: 1.6.2, python3


Code:


#!/usr/bin/env python3

"""RTSP restreamer based on GStreamer."""

import gi
gi.require_version('Gst', '1.0')
gi.require_version('GstRtspServer', '1.0')
from gi.repository import Gst, GstRtspServer, GObject

loop = GObject.MainLoop()
GObject.threads_init()
Gst.init(None)


class AVPipeline(Gst.Pipeline):
    
    def __init__(self):
        Gst.Pipeline.__init__(self)

        # rtsp source
        rtspsrc = Gst.ElementFactory.make('rtspsrc', None)
        rtspsrc.set_property('location', 'rtsp://admin:admin@192.168.7.217')
        rtspsrc.set_property('latency', 500)
        rtspsrc.set_property('timeout', 2000000)

        self.add(rtspsrc)
        self.link(rtspsrc)
        rtspsrc.connect('pad-added', self.on_pad_added)

        # video
        vqueue = Gst.ElementFactory.make('queue', None)
        rtph264depay = Gst.ElementFactory.make('rtph264depay', None)
        rtph264pay = Gst.ElementFactory.make('rtph264pay', None)
 
        rtph264pay.set_property('name', 'pay0')
        rtph264pay.set_property('pt', 96)
 
        self.add(vqueue)
        self.add(rtph264depay)
        self.add(rtph264pay)

        vqueue.link(rtph264depay)
        rtph264depay.link(rtph264pay)
        
        self._tolink_video_elem = vqueue
 
    def on_pad_added(self, element, pad):
        string = pad.query_caps(None).to_string()
        if string.startswith('application/x-rtp'):
            if 'media=(string)video' in string:
                pad.link(self._tolink_video_elem.get_static_pad('sink'))
                print('Video connected')

            elif 'media=(string)audio' in string:
 
                # create audio
                # Client doesn't get audio when I add audio elements in this point

                #audio
                aqueue = Gst.ElementFactory.make('queue', None)
                rtppcmudepay = Gst.ElementFactory.make('rtppcmudepay', None)
                rtppcmupay = Gst.ElementFactory.make('rtppcmupay', None)
        
                rtppcmupay.set_property('name', 'pay1')
             
                self.add(aqueue)
                self.add(rtppcmudepay)
                self.add(rtppcmupay)
        
                aqueue.link(rtppcmudepay)
                rtppcmudepay.link(rtppcmupay)

                for elem in (aqueue, rtppcmudepay, rtppcmupay):
                    elem.sync_state_with_parent()
   
                pad.link(aqueue.get_static_pad('sink'))
                print('Audio connected')


class MyRTSPMediaFactory(GstRtspServer.RTSPMediaFactory):

    LATENCY = 10000

    def __init__(self):
        GstRtspServer.RTSPMediaFactory.__init__(self)

        self.set_shared(True)
        self.set_property('latency', self.LATENCY)        
        self.set_transport_mode(GstRtspServer.RTSPTransportMode.PLAY)

    def do_create_element(self, url):
        return AVPipeline()


class Restreamer(object):

    def __init__(self, host, port):
        self._server = GstRtspServer.RTSPServer()
        self._server.set_address(host)
        self._server.set_service(str(port))

        mount_points = self._server.get_mount_points()
        factory = MyRTSPMediaFactory()
        mount_points.add_factory('/test', factory)

        self._server.attach(None)


def main():
    server = Restreamer('0.0.0.0', 9999)
    print('Started %s:%s' % (server._server.get_address(),
                             server._server.get_service()))
    loop.run()


if __name__ == '__main__':
    main()

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