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<p class="MsoNormal"><span lang="EN-US">Hello everyone<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I am trying to add a one byte header extension to RTP packets using GstSharp without any success.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Platform: Windows<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">GStreamer: V1.16.0<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">GstSharp: V1.16.0<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I am adding the header extension using a DataProbe on the source pad of the RTP Payloader<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Using native c code as below everything works fine and I can see the extension on the Access-Delimiter packets in Wireshark<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:blue">static</span><span style="font-size:9.5pt;font-family:Consolas;color:black">
</span><span style="font-size:9.5pt;font-family:Consolas;color:#2B91AF">GstPadProbeReturn</span><span style="font-size:9.5pt;font-family:Consolas;color:black"> cb_have_data(</span><span style="font-size:9.5pt;font-family:Consolas;color:#2B91AF">GstPad</span><span style="font-size:9.5pt;font-family:Consolas;color:black">*
</span><span style="font-size:9.5pt;font-family:Consolas;color:gray">pad</span><span style="font-size:9.5pt;font-family:Consolas;color:black">,
</span><span style="font-size:9.5pt;font-family:Consolas;color:#2B91AF">GstPadProbeInfo</span><span style="font-size:9.5pt;font-family:Consolas;color:black">*
</span><span style="font-size:9.5pt;font-family:Consolas;color:gray">info</span><span style="font-size:9.5pt;font-family:Consolas;color:black">,
</span><span style="font-size:9.5pt;font-family:Consolas;color:#2B91AF">gpointer</span><span style="font-size:9.5pt;font-family:Consolas;color:black">
</span><span style="font-size:9.5pt;font-family:Consolas;color:gray">user_data</span><span style="font-size:9.5pt;font-family:Consolas;color:black">)<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black">{<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black">
</span><span style="font-size:9.5pt;font-family:Consolas;color:#2B91AF">GstBuffer</span><span style="font-size:9.5pt;font-family:Consolas;color:black">* buffer;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black"> buffer =
</span><span style="font-size:9.5pt;font-family:Consolas;color:#6F008A">GST_PAD_PROBE_INFO_BUFFER</span><span style="font-size:9.5pt;font-family:Consolas;color:black">(</span><span style="font-size:9.5pt;font-family:Consolas;color:gray">info</span><span style="font-size:9.5pt;font-family:Consolas;color:black">);<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black"> buffer =
</span><span style="font-size:9.5pt;font-family:Consolas;color:#6F008A">gst_buffer_make_writable</span><span style="font-size:9.5pt;font-family:Consolas;color:black">(buffer);<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black">
</span><span style="font-size:9.5pt;font-family:Consolas;color:green">/* Making a buffer writable can fail (for example if it</span><span style="font-size:9.5pt;font-family:Consolas;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:green"> * cannot be copied and is used more than once)</span><span style="font-size:9.5pt;font-family:Consolas;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:green"> */</span><span style="font-size:9.5pt;font-family:Consolas;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black">
</span><span style="font-size:9.5pt;font-family:Consolas;color:blue">if</span><span style="font-size:9.5pt;font-family:Consolas;color:black"> (buffer ==
</span><span style="font-size:9.5pt;font-family:Consolas;color:#6F008A">NULL</span><span style="font-size:9.5pt;font-family:Consolas;color:black">)<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black">
</span><span style="font-size:9.5pt;font-family:Consolas;color:blue">return</span><span style="font-size:9.5pt;font-family:Consolas;color:black">
</span><span style="font-size:9.5pt;font-family:Consolas;color:darkslategray">GST_PAD_PROBE_OK</span><span style="font-size:9.5pt;font-family:Consolas;color:black">;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black">
<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black">
</span><span style="font-size:9.5pt;font-family:Consolas;color:green">/* Calling gst_rtp_buffer_map fails unless we use
</span><span style="font-size:9.5pt;font-family:Consolas;color:#4B732F">GST_RTP_BUFFER_INIT</span><span style="font-size:9.5pt;font-family:Consolas;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:green"> * Asserts that rtp->buffer == NULL is false</span><span style="font-size:9.5pt;font-family:Consolas;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:green"> */</span><span style="font-size:9.5pt;font-family:Consolas;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black">
</span><span style="font-size:9.5pt;font-family:Consolas;color:#2B91AF">GstRTPBuffer</span><span style="font-size:9.5pt;font-family:Consolas;color:black"> rtp_buffer =
</span><span style="font-size:9.5pt;font-family:Consolas;color:#6F008A">GST_RTP_BUFFER_INIT</span><span style="font-size:9.5pt;font-family:Consolas;color:black">;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black">
</span><span style="font-size:9.5pt;font-family:Consolas;color:blue">if</span><span style="font-size:9.5pt;font-family:Consolas;color:black"> (gst_rtp_buffer_map(buffer,
</span><span style="font-size:9.5pt;font-family:Consolas;color:#6F008A">GST_MAP_READWRITE</span><span style="font-size:9.5pt;font-family:Consolas;color:black">, &rtp_buffer))<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black"> {<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black">
</span><span style="font-size:9.5pt;font-family:Consolas;color:blue">const</span><span style="font-size:9.5pt;font-family:Consolas;color:black">
</span><span style="font-size:9.5pt;font-family:Consolas;color:#2B91AF">gchar</span><span style="font-size:9.5pt;font-family:Consolas;color:black">* data =
</span><span style="font-size:9.5pt;font-family:Consolas;color:#A31515">"Test"</span><span style="font-size:9.5pt;font-family:Consolas;color:black">;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black">
</span><span style="font-size:9.5pt;font-family:Consolas;color:#2B91AF">gboolean</span><span style="font-size:9.5pt;font-family:Consolas;color:black"> added = gst_rtp_buffer_add_extension_onebyte_header(&rtp_buffer, 1, data,
</span><span style="font-size:9.5pt;font-family:Consolas;color:blue">sizeof</span><span style="font-size:9.5pt;font-family:Consolas;color:black">(data));<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black"> gst_rtp_buffer_unmap(&rtp_buffer);<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black"> }<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:black">
</span><span style="font-size:9.5pt;font-family:Consolas;color:blue">return</span><span style="font-size:9.5pt;font-family:Consolas;color:black">
</span><span style="font-size:9.5pt;font-family:Consolas;color:darkslategray">GST_PAD_PROBE_OK</span><span style="font-size:9.5pt;font-family:Consolas;color:black">;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.5pt;font-family:Consolas;color:black">}<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.5pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:black">Using the C# wrapper the underlying code asserts that rtp->buffer == NULL is false.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:black">Looking at the Wrapper code it would appear that it passes in an uninitialized chunk of memory as below<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-GB"> public static bool Map(Gst.Buffer buffer, Gst.MapFlags flags, out Gst.Rtp.RTPBuffer rtp) {<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-GB"> IntPtr native_rtp = Marshal.AllocHGlobal (Marshal.SizeOf (typeof (Gst.Rtp.RTPBuffer)));<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-GB"> bool raw_ret = gst_rtp_buffer_map(buffer == null ? IntPtr.Zero : buffer.Handle, (int) flags, native_rtp);<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-GB"> bool ret = raw_ret;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-GB"> rtp = Gst.Rtp.RTPBuffer.New (native_rtp);<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-GB"> Marshal.FreeHGlobal (native_rtp);<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-GB"> return ret;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-GB"> }<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I am unsure if this is a bug in the GstSharp Code or whether it would be in the core code, ie the GstRTPBuffer code should do the initialization<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Kind Regards<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Jon L<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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