add isAvailabe() for AVOutput. If open init/failed, it's false

TODO: DO NOT decode(or at least convert data) if the output is not
available

src/AOPortAudio.cpp

@@ -77,10 +77,13 @@ bool AOPortAudio::open()
     //
     d.outputParameters->channelCount = d.channels;
     PaError err = Pa_OpenStream(&d.stream, NULL, d.outputParameters, d.sample_rate, 0, paNoFlag, NULL, NULL);
-    if (err == paNoError)
+    if (err == paNoError) {
         d.outputLatency = Pa_GetStreamInfo(d.stream)->outputLatency;
-    else
+        d.available = true;
+    } else {
         qWarning("Open portaudio stream error: %s", Pa_GetErrorText(err));
+        d.available = false;
+    }
     return err == paNoError;
 }
 

src/AVOutput.cpp

@@ -46,6 +46,11 @@ bool AVOutput::writeData(const QByteArray &data)
 	return result;
 }
 
+bool AVOutput::isAvailable() const
+{
+    return d_func().available;
+}
+
 void AVOutput::pause(bool p)
 {
     DPTR_D(AVOutput);

src/QtAV/AVOutput.h

@@ -33,7 +33,8 @@ class Q_EXPORT AVOutput
     AVOutput();
     virtual ~AVOutput() = 0;
     //Call tryPause() first to try to pause
-	bool writeData(const QByteArray& data);
+    bool writeData(const QByteArray& data);
+    bool isAvailable() const;
     virtual bool open() = 0;
     virtual bool close() = 0;
     //Demuxer thread automatically paused because packets will be full

src/QtAV/private/AOPortAudio_p.h

@@ -29,25 +29,38 @@ class Q_EXPORT AOPortAudioPrivate : public AudioOutputPrivate
 {
 public:
     AOPortAudioPrivate():outputParameters(new PaStreamParameters)
-      ,stream(0)
+      ,stream(0),initialized(true)
     {
-        Pa_Initialize();
+        PaError err = paNoError;
+        if ((err = Pa_Initialize()) != paNoError) {
+            qWarning("Error when init portaudio: %s", Pa_GetErrorText(err));
+            available = false;
+            initialized = false;
+            return;
+        }
 
         memset(outputParameters, 0, sizeof(PaStreamParameters));
         outputParameters->device = Pa_GetDefaultOutputDevice();
+        if (outputParameters->device == paNoDevice) {
+            qWarning("PortAudio get device error!");
+            available = false;
+            return;
+        }
         outputParameters->sampleFormat = paFloat32;
         outputParameters->hostApiSpecificStreamInfo = NULL;
         outputParameters->suggestedLatency = Pa_GetDeviceInfo(outputParameters->device)->defaultHighOutputLatency;
 
     }
     ~AOPortAudioPrivate() {
-        Pa_Terminate();
+        if (initialized)
+            Pa_Terminate(); //Do NOT call this if init failed. See document
         if (outputParameters) {
             delete outputParameters;
             outputParameters = 0;
         }
     }
 
+    bool initialized;
     PaStreamParameters *outputParameters;
     PaStream *stream;
 #ifdef Q_OS_LINUX

src/QtAV/private/AVOutput_p.h

@@ -30,12 +30,13 @@ class AVDecoder;
 class Q_EXPORT AVOutputPrivate : public DPtrPrivate<AVOutput>
 {
 public:
-    AVOutputPrivate():paused(false) {}
+    AVOutputPrivate():paused(false),available(true) {}
     virtual ~AVOutputPrivate() {
         cond.wakeAll(); //WHY: failed to wake up
     }
 
     bool paused;
+    bool available;
     QMutex mutex; //pause
     QWaitCondition cond; //pause
 };

src/VideoThread.cpp

@@ -116,9 +116,9 @@ void VideoThread::run()
             d.width = dec->width();
             d.height = dec->height();
             d.decoded_data = d.dec->data();
-            if (d.writer) {
+            if (d.writer && d.writer->isAvailable()) {
                 ((VideoRenderer*)d.writer)->setSourceSize(dec->width(), dec->height());
-				d.writer->writeData(d.dec->data());
+                d.writer->writeData(d.dec->data());
             }
             //qApp->processEvents(QEventLoop::AllEvents);
         }