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<p class="MsoNormal"><a name="_MailEndCompose"><span style="color:#1F497D">After some sparring with a colleague and some further trial and error, I was able solve this issue. Posting here for posterity ;-)<o:p></o:p></span></a></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">In my original question, I had left out some pipeline details that turned out to be key. Here are the first elements of my pipeline (truncated to just the relevant pieces) that had the error:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<span style="font-size:9.0pt;font-family:"Courier New";color:#1D1C1D;mso-fareast-language:EN-GB">appsrc name=audio-src caps=audio/x-raw,rate=16000,channels=1,format=S16LE,layout=interleaved stream-type=stream block=true do-timestamp=true is-live=true ! queue<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Notice that it specifies all the caps on the appsrc element itself. The solution was to move these to a separate capsfilter following the appsrc slement:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;color:#1D1C1D">appsrc name=audio-src format=3 is-live=1 do-timestamp=1 ! audio/x-raw, channels=1, rate=16000, format=S16LE, layout=interleaved ! queue<o:p></o:p></span></pre>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I won’t pretend to understand what the difference is, since I’m still quite new to GStreamer. If anyone has a good explanation, I’d love to hear it.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:9.0pt;font-family:"Verdana",sans-serif;color:#86807D;mso-fareast-language:EN-GB">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:9.0pt;font-family:"Verdana",sans-serif;color:#86807D;mso-fareast-language:EN-GB">Thorsten</span><span style="color:#1F497D"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Times New Roman",serif;color:#1F497D;mso-fareast-language:EN-GB"><img width="1" height="1" id="_x0000_i1025" src="https://t-eu.xink.io/Tracking/Impression/_BoAAAJgAAAOXzkA0" alt="."></span><span style="color:#1F497D"><o:p></o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="mso-fareast-language:EN-GB">From:</span></b><span lang="EN-US" style="mso-fareast-language:EN-GB"> gstreamer-devel [mailto:gstreamer-devel-bounces@lists.freedesktop.org]
<b>On Behalf Of </b>Soebirk, Thorsten<br>
<b>Sent:</b> 23 June 2020 10:35<br>
<b>To:</b> Discussion of the development of and with GStreamer <gstreamer-devel@lists.freedesktop.org><br>
<b>Subject:</b> Trouble getting appsrc to work<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am working on a custom appsrc that produces audio and will ultimately stream it via webrtcbin. The pipeline looks like this (some details left out for clarity):<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">appsrc ! queue ! opusenc ! rtpopuspay ! queue ! capsfilter<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">It gets connected to webrtcbin in my code. The pipeline starts up correctly and begins playing, but as soon as appsrc.push_buffer is called, GStreamer throws the following errors.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">GStreamer-WARNING **: 09:53:28.785: ../gst/gstpad.c:4551:gst_pad_push_data:<opusenc0:src> Got data flow before segment event<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">GStreamer-WARNING **: 09:53:28.785: ../gst/gstpad.c:4298:gst_pad_chain_data_unchecked:<rtpopuspay0:sink> Got data flow before segment event<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">GStreamer-CRITICAL **: 09:53:28.785: gst_segment_to_running_time: assertion 'segment->format == format' failed<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">GStreamer-WARNING **: 09:53:28.785: ../gst/gstpad.c:4551:gst_pad_push_data:<rtpopuspay0:src> Got data flow before segment event<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I have tried replacing my appsrc with audiotestsrc, and in this case the pipeline works and there are no errors.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I have tried troublehooting by replacing elements with fakesink, e.g. “appsrc ! fakesink”, “appsrc ! queue ! opusenc ! fakesink”, etc. The errors start occurring when rtpopuspay appears in the pipeline.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I have tried sending a SEGMENT event before calling push_buffer, but this doesn’t change anything. Admittedly, I am not sure how to populate the SEGMENT event if it is relevant. I looked through the source code of audiotestsrc, and as far
as I can tell, it does not send a SEGMENT event.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Can anyone see what I am doing wrong?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Verdana",sans-serif;color:#86807D;mso-fareast-language:EN-GB">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Verdana",sans-serif;color:#86807D;mso-fareast-language:EN-GB">Thorsten</span><span style="font-size:12.0pt;mso-fareast-language:EN-GB"><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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