From 29befed6855ba421ab8e3418d11890754cf0c0ae Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Olivier=20Cr=C3=AAte?= <olivier.crete@collabora.com>
Date: Tue, 14 Dec 2021 11:28:13 -0500
Subject: [PATCH] webrtcbin: Store the ssrc of the last received packet

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1448>
---
 .../gst-plugins-bad/ext/webrtc/gstwebrtcbin.c | 34 +++++++++++++++++++
 .../gst-plugins-bad/ext/webrtc/gstwebrtcbin.h |  2 ++
 2 files changed, 36 insertions(+)

diff --git a/subprojects/gst-plugins-bad/ext/webrtc/gstwebrtcbin.c b/subprojects/gst-plugins-bad/ext/webrtc/gstwebrtcbin.c
index 917a98240a..86fd6437a1 100644
--- a/subprojects/gst-plugins-bad/ext/webrtc/gstwebrtcbin.c
+++ b/subprojects/gst-plugins-bad/ext/webrtc/gstwebrtcbin.c
@@ -439,6 +439,37 @@ gst_webrtc_bin_pad_init (GstWebRTCBinPad * pad)
 {
 }
 
+static GstPadProbeReturn
+webrtc_bin_pad_buffer_cb (GstPad * pad, GstPadProbeInfo * info,
+    gpointer user_data)
+{
+  GstWebRTCBinPad *wpad;
+  GstBuffer *buf;
+  GstRTPBuffer rtpbuf = GST_RTP_BUFFER_INIT;
+
+  if (info->type & GST_PAD_PROBE_TYPE_BUFFER) {
+    buf = GST_PAD_PROBE_INFO_BUFFER (info);
+  } else {
+    GstBufferList *list;
+
+    list = GST_PAD_PROBE_INFO_BUFFER_LIST (info);
+    buf = gst_buffer_list_get (list, 0);
+  }
+
+  if (buf == NULL)
+    return GST_PAD_PROBE_OK;
+
+  if (!gst_rtp_buffer_map (buf, GST_MAP_READ, &rtpbuf))
+    return GST_PAD_PROBE_OK;
+
+  wpad = GST_WEBRTC_BIN_PAD (pad);
+  wpad->last_ssrc = gst_rtp_buffer_get_ssrc (&rtpbuf);
+
+  gst_rtp_buffer_unmap (&rtpbuf);
+
+  return GST_PAD_PROBE_OK;
+}
+
 static GstWebRTCBinPad *
 gst_webrtc_bin_pad_new (const gchar * name, GstPadDirection direction)
 {
@@ -460,6 +491,9 @@ gst_webrtc_bin_pad_new (const gchar * name, GstPadDirection direction)
   gst_pad_set_event_function (GST_PAD (pad), gst_webrtcbin_sink_event);
   gst_pad_set_query_function (GST_PAD (pad), gst_webrtcbin_sink_query);
 
+  gst_pad_add_probe (GST_PAD (pad), GST_PAD_PROBE_TYPE_BUFFER |
+      GST_PAD_PROBE_TYPE_BUFFER_LIST, webrtc_bin_pad_buffer_cb, NULL, NULL);
+
   GST_DEBUG_OBJECT (pad, "new visible pad with direction %s",
       direction == GST_PAD_SRC ? "src" : "sink");
   return pad;
diff --git a/subprojects/gst-plugins-bad/ext/webrtc/gstwebrtcbin.h b/subprojects/gst-plugins-bad/ext/webrtc/gstwebrtcbin.h
index e2ef991ebc..b80a54ad67 100644
--- a/subprojects/gst-plugins-bad/ext/webrtc/gstwebrtcbin.h
+++ b/subprojects/gst-plugins-bad/ext/webrtc/gstwebrtcbin.h
@@ -46,6 +46,8 @@ struct _GstWebRTCBinPad
   GstWebRTCRTPTransceiver *trans;
   gulong                block_id;
 
+  guint32               last_ssrc;
+
   GstCaps              *received_caps;
 };