added: parse JSON coming from kodi, if there is a notification that playback has started, switch on the amplifier

src/ampswitch.cpp

@@ -52,6 +52,7 @@ CAmpSwitch::CAmpSwitch(int argc, char *argv[])
   m_switchedon    = false;
   m_samplecounter = 0;
   m_usekodi       = false;
+  m_playstart     = false;
 
   struct option longoptions[] =
   {
@@ -138,7 +139,7 @@ bool CAmpSwitch::Setup()
     printf("off command: \"%s\"\n", m_offcommand);
 
   if (m_usekodi)
-    m_kodiclient.Start(); //start a thread that connects to Kodi's JSONRPC
+    m_kodiclient.Start(this); //start a thread that connects to Kodi's JSONRPC
 
   return true;
 }
@@ -321,6 +322,14 @@ int CAmpSwitch::PJackProcessCallback(jack_nframes_t nframes)
   {
     //if the absolute sample value is higher than the trigger level, set the switch state to on and reset the sample counter
     bool trigger = fabsf(*(in++)) > m_triggerlevel;
+
+    //Consider a playback start as a trigger.
+    if (m_playstart)
+    {
+      trigger = true;
+      m_playstart = false;
+    }
+
     if (trigger)
     {
       m_samplecounter = std::max((int)lround(m_switchtime * m_samplerate), 1);
@@ -381,3 +390,8 @@ void CAmpSwitch::SignalHandler(int signum)
     g_stop = true;
 }
 
+void CAmpSwitch::SignalPlayStart()
+{
+  //Signal the jack client thread that playback has started.
+  m_playstart = true;
+}

src/ampswitch.h

@@ -28,27 +28,29 @@ class CAmpSwitch
     CAmpSwitch(int argc, char *argv[]);
     ~CAmpSwitch();
 
-    bool Setup();
-    void Process();
-    void Cleanup();
+    bool           Setup();
+    void           Process();
+    void           Cleanup();
+
+    void           SignalPlayStart();
 
   private:
-    void        PrintHelpMessage();
+    void           PrintHelpMessage();
 
-    void        Connect();
-    bool        JackConnect();
-    void        JackDisconnect();
+    void           Connect();
+    bool           JackConnect();
+    void           JackDisconnect();
 
-    static int  SJackProcessCallback(jack_nframes_t nframes, void *arg);
-    int         PJackProcessCallback(jack_nframes_t nframes);
+    static int     SJackProcessCallback(jack_nframes_t nframes, void *arg);
+    int            PJackProcessCallback(jack_nframes_t nframes);
 
-    static int  SJackSamplerateCallback(jack_nframes_t nframes, void *arg);
-    int         PJackSamplerateCallback(jack_nframes_t nframes);
+    static int     SJackSamplerateCallback(jack_nframes_t nframes, void *arg);
+    int            PJackSamplerateCallback(jack_nframes_t nframes);
 
-    static void SJackInfoShutdownCallback(jack_status_t code, const char *reason, void *arg);
-    void        PJackInfoShutdownCallback(jack_status_t code, const char *reason);
+    static void    SJackInfoShutdownCallback(jack_status_t code, const char *reason, void *arg);
+    void           PJackInfoShutdownCallback(jack_status_t code, const char *reason);
 
-    static void SignalHandler(int signum);
+    static void    SignalHandler(int signum);
 
     float          m_triggerlevel;
     float          m_switchtime;
@@ -68,6 +70,7 @@ class CAmpSwitch
 
     bool           m_usekodi;
     CKodiClient    m_kodiclient;
+    bool           m_playstart;
 };
 
 #endif //AMPSWITCH_H

src/kodiclient.cpp

@@ -17,6 +17,7 @@
  */
 
 #include "kodiclient.h"
+#include "ampswitch.h"
 
 #include <cstdio>
 #include <unistd.h>
@@ -24,14 +25,18 @@
 #include <iostream>
 #include <boost/asio.hpp>
 
+#include <nlohmann/json.hpp>
+
 using namespace boost::asio;
 using ip::tcp;
 using std::string;
 using std::cout;
 using std::endl;
+using namespace nlohmann;
 
-void CKodiClient::Start()
+void CKodiClient::Start(CAmpSwitch* ampswitch)
 {
+  m_ampswitch = ampswitch;
   m_thread = std::thread(SProcess, this);
 }
 
@@ -56,6 +61,8 @@ void CKodiClient::Process()
       //Connect to Kodi's JSONRPC, this will thrown an exception on failure.
       socket.connect(tcp::endpoint(address, 9090));
 
+      printf("Connected to Kodi\n");
+
       //Keep reading data from Kodi, when the tcp socket is closed an exception is thrown.
       for(;;)
       {
@@ -63,8 +70,18 @@ void CKodiClient::Process()
         size_t readbytes = boost::asio::read(socket, receive_buffer, boost::asio::transfer_at_least(1));
         const char* data = boost::asio::buffer_cast<const char*>(receive_buffer.data());
 
-        printf("Received %i bytes: %s\n", (int)readbytes, data);
-        printf("Data length: %i\n", (int)strlen(data));
+        //TODO: because of TCP, one read does not exactly equal one JSON object.
+        json jsondata = json::parse(data);
+
+        //If Kodi signals a Player.OnPlay notification, the amplifier should be turned on.
+        if (jsondata.contains("method"))
+        {
+          if (jsondata["method"] == "Player.OnPlay")
+          {
+            printf("Player started\n");
+            m_ampswitch->SignalPlayStart();
+          }
+        }
       }
     }
     catch(boost::system::system_error& error)

src/kodiclient.h

@@ -16,16 +16,24 @@
  * with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#ifndef KODICLIENT_H
+#define KODICLIENT_H
+
 #include <thread>
 
+class CAmpSwitch;
+
 class CKodiClient
 {
   public:
-    void        Start();
+    void        Start(CAmpSwitch* ampswitch);
 
   private:
     static void SProcess(CKodiClient* kodiclient);
     void        Process();
 
     std::thread m_thread;
+    CAmpSwitch* m_ampswitch;
 };
+
+#endif //KODICLIENT_H

wscript

@@ -17,6 +17,7 @@ def configure(conf):
 
   conf.check(header_name='jack/jack.h')
   conf.check(header_name='boost/asio.hpp')
+  conf.check(header_name='nlohmann/json.hpp')
 
   conf.check(lib='jack', uselib_store='jack', mandatory=True)
   conf.check(lib='pthread', uselib_store='pthread', mandatory=False)