make relative gain control in route groups work (again)

[ardour.git] / libs / midi++2 / ipmidi_port.cc

diff --git a/libs/midi++2/ipmidi_port.cc b/libs/midi++2/ipmidi_port.cc
index 6955bd9f86ab9c8506201039f039c997455a4118..fd5cb9a2395e727a457dda57104038439ea0429b 100644 (file)
--- a/libs/midi++2/ipmidi_port.cc
+++ b/libs/midi++2/ipmidi_port.cc
@@ -194,7 +194,7 @@ IPMIDIPort::open_sockets (int base_port, const string& ifname)
 #endif
 
        struct ip_mreq mreq;
-       mreq.imr_multiaddr.s_addr = ::inet_addr("225.0.0.37");
+       mreq.imr_multiaddr.s_addr = ::inet_addr("225.0.0.37"); /* ipMIDI group multicast address */
        mreq.imr_interface.s_addr = if_addr_in.s_addr;
        if(::setsockopt (sockin, IPPROTO_IP, IP_ADD_MEMBERSHIP, (char *) &mreq, sizeof(mreq)) < 0) {
                ::perror("setsockopt(IP_ADD_MEMBERSHIP)");
@@ -233,7 +233,37 @@ IPMIDIPort::open_sockets (int base_port, const string& ifname)
 
        // Turn off loopback...
        int loop = 0;
-       if (::setsockopt(sockout, IPPROTO_IP, IP_MULTICAST_LOOP, (char *) &loop, sizeof (loop)) < 0) {
+
+#ifdef PLATFORM_WINDOWS
+
+       /* https://msdn.microsoft.com/en-us/library/windows/desktop/ms739161%28v=vs.85%29.aspx
+        *
+        * ------------------------------------------------------------------------------
+        * Note The Winsock version of the IP_MULTICAST_LOOP option is
+        * semantically different than the UNIX version of the
+        * IP_MULTICAST_LOOP option:
+        *
+        * In Winsock, the IP_MULTICAST_LOOP option applies only to the receive path.
+        * In the UNIX version, the IP_MULTICAST_LOOP option applies to the send path.
+        *
+        * For example, applications ON and OFF (which are easier to track than
+        * X and Y) join the same group on the same interface; application ON
+        * sets the IP_MULTICAST_LOOP option on, application OFF sets the
+        * IP_MULTICAST_LOOP option off. If ON and OFF are Winsock
+        * applications, OFF can send to ON, but ON cannot sent to OFF. In
+        * contrast, if ON and OFF are UNIX applications, ON can send to OFF,
+        * but OFF cannot send to ON.
+        * ------------------------------------------------------------------------------
+        *
+        * Alles klar? Gut! 
+        */
+
+       const int target_sock = sockin;
+#else
+       const int target_sock = sockout;
+#endif
+
+       if (::setsockopt (target_sock, IPPROTO_IP, IP_MULTICAST_LOOP, (char *) &loop, sizeof (loop)) < 0) {
                ::perror("setsockopt(IP_MULTICAST_LOOP)");
                return false;
        }
@@ -301,10 +331,6 @@ IPMIDIPort::parse (framecnt_t timestamp)
        socklen_t slen = sizeof(sender);
        int r = ::recvfrom (sockin, (char *) buf, sizeof(buf), 0, (struct sockaddr *) &sender, &slen);
 
-       if (r != 18) {
-               cout << "IPMIDI: received from socket: " << r << endl;
-       }
-
        if (r >= 0) {
 
                _parser->set_timestamp (timestamp);