Echo cancelling with webrtcdsp

[mwon]

I'm trying to establish an audio call to a Raspberry Pi equipped with
speakers and mic. I'm using a webrtc connection using /webrtcbin/ that
allows me to connect my browser to Raspberry Pi. The problem is that when I
send audio to the Raspberry Pi, I get echo because the Raspi Pi mic records
the speaker audio and send it back. 

I'm trying to use /webrtcdsp/ with /webrtcechoprobe/ to solve the issue, but
the problem is that the probe must be positioned when the remote sound
arrives (from the browser) so that /webrtcdsp/ filter it. For these reasons
I was testing  this example
<https://github.com/centricular/gstwebrtc-demos/blob/master/sendrecv/gst/webrtc-sendrecv.c>  
with the with the following pipeline:


/  pipe1 =
      gst_parse_launch ("webrtcbin bundle-policy=max-bundle name=sendrecv "
      STUN_SERVER
      "alsasrc device=hw:1,0 buffer-time=30000  ! audioconvert ! webrtcdsp !
audioresample ! queue ! opusenc ! rtpopuspay ! "
      "queue ! " RTP_CAPS_OPUS "96 ! sendrecv. ", &error);
/



and then add the probe just after the incoming decoding bin: 



/handle_media_stream (GstPad * pad, GstElement * pipe, const char
*convert_name,
    const char *sink_name)
{
  GstPad *qpad;
  GstElement *q, *conv, *resample, *sink,*probe;
  GstPadLinkReturn ret;

  g_print ("Trying to handle stream with %s ! %s", convert_name, sink_name);

  q = gst_element_factory_make ("queue", NULL);
  g_assert_nonnull (q);
  conv = gst_element_factory_make (convert_name, NULL);
  g_assert_nonnull (conv);
  probe = gst_element_factory_make ("webrtcechoprobe", NULL);
  g_assert_nonnull (probe);
  sink = gst_element_factory_make (sink_name, NULL);
  g_assert_nonnull (sink);

  gst_bin_add_many (GST_BIN (pipe), q, conv,sink, NULL);
  gst_element_sync_state_with_parent (q);
  gst_element_sync_state_with_parent (conv);
  gst_element_sync_state_with_parent (probe);
  gst_element_sync_state_with_parent (sink);
  gst_element_link_many (q, conv,probe,sink, NULL);


  qpad = gst_element_get_static_pad (q, "sink");

  ret = gst_pad_link (pad, qpad);
  g_assert_cmphex (ret, ==, GST_PAD_LINK_OK);
}/


The problem is that the example is not able to run. The initial pipeline is
not executed at all because it is missing the corresponding probe (I think),
that will be ready only when the connection is established. 

Any idea on how to solve the problem?






--
Sent from: http://gstreamer-devel.966125.n4.nabble.com/