initialize portaudio playback only once

Vocaluxe/Lib/Sound/CPortAudioPlay.cs

@@ -388,7 +388,9 @@ namespace Vocaluxe.Lib.Sound
         const long BEGINREFILL = 800000L;
 
         private CSyncTimer _SyncTimer;
-        private bool _Initialized;
+        private static bool _Initialized = false;
+        private static int _NumStreams = 0;
+        private static Object _Mutex = new object();
         private int _ByteCount = 4;
         private float _Volume = 1f;
         private float _VolumeMax = 1f;
@@ -403,8 +405,8 @@ namespace Vocaluxe.Lib.Sound
         private bool _fading = false;
 
 
-        private PortAudio.PaHostApiInfo _apiInfo;
-        private PortAudio.PaDeviceInfo _outputDeviceInfo;
+        private static PortAudio.PaHostApiInfo _apiInfo;
+        private static PortAudio.PaDeviceInfo _outputDeviceInfo;
         private IntPtr _Ptr = new IntPtr(0);
 
         private Stopwatch _FadeTimer = new Stopwatch();
@@ -446,7 +448,6 @@ namespace Vocaluxe.Lib.Sound
 
         public PortAudioStream()
         {
-            _Initialized = false;
             _SyncTimer = new CSyncTimer(0f, 1f, 0.02f);
             _DecoderThread = new Thread(Execute);
         }
@@ -578,12 +579,18 @@ namespace Vocaluxe.Lib.Sound
         {
             Paused = false;
             _pauseStreamAfterFade = false;
-            errorCheck("StartStream", PortAudio.Pa_StartStream(_Ptr));
+            lock (_Mutex)
+            {
+                errorCheck("StartStream", PortAudio.Pa_StartStream(_Ptr));
+            }
         }
 
         public void Stop()
         {
-            errorCheck("StartStream", PortAudio.Pa_StopStream(_Ptr));
+            lock (_Mutex)
+            {
+                errorCheck("StopStream (playback)", PortAudio.Pa_StopStream(_Ptr));
+            }
             Skip(0f);
         }
 
@@ -609,17 +616,23 @@ namespace Vocaluxe.Lib.Sound
 
             try
             {
-                if (errorCheck("Initialize", PortAudio.Pa_Initialize()))
-                    return -1;
+                lock (_Mutex)
+                {
+                    if (!_Initialized)
+                    {
+                        if (errorCheck("Initialize", PortAudio.Pa_Initialize()))
+                            return -1;
+                        _Initialized = true;
 
-                _Initialized = true;
-                int hostApi = apiSelect();
-                _apiInfo = PortAudio.Pa_GetHostApiInfo(hostApi);
-                _outputDeviceInfo = PortAudio.Pa_GetDeviceInfo(_apiInfo.defaultOutputDevice);
-                _paStreamCallback = new PortAudio.PaStreamCallbackDelegate(_PaStreamCallback);
+                        int hostApi = apiSelect();
+                        _apiInfo = PortAudio.Pa_GetHostApiInfo(hostApi);
+                        _outputDeviceInfo = PortAudio.Pa_GetDeviceInfo(_apiInfo.defaultOutputDevice);
+                        if (_outputDeviceInfo.defaultLowOutputLatency < 0.1)
+                            _outputDeviceInfo.defaultLowOutputLatency = 0.1;
+                    }
+                }
 
-                if (_outputDeviceInfo.defaultLowOutputLatency < 0.1)
-                    _outputDeviceInfo.defaultLowOutputLatency = 0.1;
+                _paStreamCallback = new PortAudio.PaStreamCallbackDelegate(_PaStreamCallback);         
             }
 
             catch (Exception)
@@ -634,6 +647,9 @@ namespace Vocaluxe.Lib.Sound
             _Duration = _Decoder.GetLength();
 
             FormatInfo format = _Decoder.GetFormatInfo();
+            if (format.SamplesPerSecond == 0)
+                return -1;
+
             _ByteCount = 2 * format.ChannelCount;
             _BytesPerSecond = format.SamplesPerSecond * _ByteCount;
             _CurrentTime = 0f;
@@ -650,20 +666,24 @@ namespace Vocaluxe.Lib.Sound
             outputParams.suggestedLatency = _outputDeviceInfo.defaultLowOutputLatency;
 
             uint bufsize = (uint)CConfig.AudioBufferSize;
-            errorCheck("OpenDefaultStream (playback)", PortAudio.Pa_OpenStream(
-                out _Ptr,
-                IntPtr.Zero,
-                ref outputParams,
-                format.SamplesPerSecond,
-                bufsize,
-                PortAudio.PaStreamFlags.paNoFlag,
-                _paStreamCallback,
-                data));
+            lock (_Mutex)
+            {
+                errorCheck("OpenDefaultStream (playback)", PortAudio.Pa_OpenStream(
+                    out _Ptr,
+                    IntPtr.Zero,
+                    ref outputParams,
+                    format.SamplesPerSecond,
+                    bufsize,
+                    PortAudio.PaStreamFlags.paNoFlag,
+                    _paStreamCallback,
+                    data));
+            }
 
             stream.handle = _Ptr.ToInt32();
 
             if (stream.handle != 0)
             {
+                _NumStreams++;
                 _Paused = true;
                 _waiting = true;
                 _FileOpened = true;
@@ -808,7 +828,15 @@ namespace Vocaluxe.Lib.Sound
             if (_Initialized)
             {
                 Stop();
-                PortAudio.Pa_Terminate();
+                _NumStreams--;
+                if (_NumStreams == 0)
+                {
+                    lock (_Mutex)
+                    {
+                        PortAudio.Pa_Terminate();
+                        _Initialized = false;
+                    }
+                }
             }
 
             _Closeproc(_StreamID);