Bugfix and add volume change hack for Vast-FMT 212R transmitters

- Fix RDS for setups where FPP does not reinitialize the FM transmitter
- Add optional code to have the plugin bump the volume down and back
  up at every song change to work around the Vast-FMT 212R audio
  glitches.

plugin_setup.php

@@ -54,6 +54,7 @@ function OnConnectionChanged() {
 At Start, the hardware is reset, FM settings initialized, will broadcast any audio played, and send static RDS messages (if enabled).</p>
 <p>Stop at: <?php PrintSettingSelect("Stop", "Stop", 2, 0, "Never", Array("Playlist Stop"=>"PlaylistStop", "Never (default)"=>"Never"), "fpp-vastfmt", ""); ?><br />
 At Stop, the hardware is reset. Listeners will hear static.</p>
+<p>Enable Volume Change Hack for Vast-FMT 212R: <?php PrintSettingCheckbox("EnableVolumeChangeHack", "EnableVolumeChangeHack", 2, 0, "1", "0", "fpp-vastfmt", ""); ?></p>
 </fieldset>
 </div>
 

src/FPPVastFM.cpp

@@ -5,6 +5,7 @@
 #include <termios.h>
 
 #include "mediadetails.h"
+#include "commands/Commands.h"
 #include "common.h"
 #include "settings.h"
 #include "Plugin.h"
@@ -120,7 +121,8 @@ class FPPVastFMPlugin : public FPPPlugin {
     void startVastForRDS() {
         if (si4713 == nullptr) {
             if (initVast()) {
-                if (settings["EnableRDS"] == "True") {
+                rdsEnabled = settings["EnableRDS"] == "True";
+                if (rdsEnabled) {
                     initRDS();
                 } else {
                     LogErr(VB_PLUGIN, "Tried to setup for RDS, but RDS is not enabled\n");
@@ -221,6 +223,21 @@ class FPPVastFMPlugin : public FPPPlugin {
         std::string album = mediaDetails.album;
         int track = mediaDetails.track;
         int length = mediaDetails.length;
+
+        // Bump the volume down and back up to work around Vast-FMT 212R issue
+        if (settings["EnableVolumeChangeHack"] == "1") {
+            Json::Value cmd;
+            Json::Value args(Json::arrayValue);
+
+            args.append("5");
+            cmd["args"] = args;
+
+            cmd["command"] = "Volume Decrease";
+            CommandManager::INSTANCE.run(cmd);
+
+            cmd["command"] = "Volume Increase";
+            CommandManager::INSTANCE.run(cmd);
+        }
 
         std::string type = playlist["currentEntry"]["type"].asString();
         if (type != "both" && type != "media") {
@@ -245,6 +262,7 @@ class FPPVastFMPlugin : public FPPPlugin {
         setIfNotFound("Pty", "2");
 
         setIfNotFound("Connection", "USB");
+        setIfNotFound("EnableVolumeChangeHack", "0");
 #ifdef PLATFORM_BBB
         setIfNotFound("ResetPin", "14");
 #else