Implement the playMono16Sound API sanely

This API used to start *A NEW THREAD* for every sound played!!

Now we simply have a dedicated source and buffer to play those sounds, we use a timer to cleanup the buffer 50ms after the sound is done playing (if a new sound hasn't started in the meantime)

src/audio/audio.cpp

@@ -51,52 +51,6 @@
     } while (0)
 #endif
 
-/**
-@class AudioPlayer
-
-@brief Non-blocking audio player.
-
-The audio data is played from start to finish (no streaming).
-*/
-class AudioPlayer : public QThread
-{
-public:
-    AudioPlayer(ALuint source, const QByteArray& data)
-        : mSource(source)
-    {
-        alGenBuffers(1, &mBuffer);
-        alBufferData(mBuffer, AL_FORMAT_MONO16, data.constData(), data.size(), 44100);
-        alSourcei(mSource, AL_BUFFER, mBuffer);
-
-        connect(this, &AudioPlayer::finished, this, &AudioPlayer::deleteLater);
-    }
-
-private:
-    void run() override final
-    {
-        alSourceRewind(mSource);
-        alSourcePlay(mSource);
-
-        QMutexLocker locker(&playLock);
-        ALint state = AL_PLAYING;
-        while (state == AL_PLAYING) {
-            alGetSourcei(mSource, AL_SOURCE_STATE, &state);
-            waitPlaying.wait(&playLock, 2000);
-        }
-
-        alSourceStop(mSource);
-        alDeleteBuffers(1, &mBuffer);
-    }
-
-public:
-    QMutex playLock;
-    QWaitCondition waitPlaying;
-
-private:
-    ALuint      mBuffer;
-    ALuint      mSource;
-};
-
 /**
 Returns the singleton instance.
 */
@@ -114,6 +68,7 @@ Audio::Audio()
     , alOutDev(nullptr)
     , alOutContext(nullptr)
     , alMainSource(0)
+    , alMainBuffer(0)
     , outputInitialized(false)
 {
     audioThread->setObjectName("qTox Audio");
@@ -129,6 +84,8 @@ Audio::Audio()
     captureTimer.setInterval(AUDIO_FRAME_DURATION/2);
     captureTimer.setSingleShot(false);
     captureTimer.start();
+    connect(&playMono16Timer, &QTimer::timeout, this, &Audio::playMono16SoundCleanup);
+    playMono16Timer.setSingleShot(true);
 
     if (!audioThread->isRunning())
         audioThread->start();
@@ -360,6 +317,16 @@ bool Audio::initOutput(QString outDevDescr)
     return true;
 }
 
+/**
+Play a 44100Hz mono 16bit PCM sound from a file
+*/
+void Audio::playMono16Sound(const QString& path)
+{
+    QFile sndFile(path);
+    sndFile.open(QIODevice::ReadOnly);
+    playMono16Sound(QByteArray(sndFile.readAll()));
+}
+
 /**
 Play a 44100Hz mono 16bit PCM sound
 */
@@ -370,27 +337,23 @@ void Audio::playMono16Sound(const QByteArray& data)
     if (!autoInitOutput())
         return;
 
-    AudioPlayer *player = new AudioPlayer(alMainSource, data);
-    connect(player, &AudioPlayer::finished, [=]() {
-        QMutexLocker locker(&audioLock);
+    if (!alMainBuffer)
+        alGenBuffers(1, &alMainBuffer);
 
-        if (outSources.isEmpty())
-            cleanupOutput();
-        else
-            qDebug("Audio output not closed -> there are pending subscriptions.");
-    });
+    ALint state;
+    alGetSourcei(alMainSource, AL_SOURCE_STATE, &state);
+    if (state == AL_PLAYING)
+    {
+        alSourceStop(alMainSource);
+        alSourcei(alMainSource, AL_BUFFER, AL_NONE);
+    }
 
-    player->start();
-}
+    alBufferData(alMainBuffer, AL_FORMAT_MONO16, data.constData(), data.size(), 44100);
+    alSourcei(alMainSource, AL_BUFFER, static_cast<ALint>(alMainBuffer));
+    alSourcePlay(alMainSource);
 
-/**
-Play a 44100Hz mono 16bit PCM sound from a file
-*/
-void Audio::playMono16Sound(const QString& path)
-{
-    QFile sndFile(path);
-    sndFile.open(QIODevice::ReadOnly);
-    playMono16Sound(QByteArray(sndFile.readAll()));
+    int durationMs = data.size() * 1000 / 2 / 44100;
+    playMono16Timer.start(durationMs + 50);
 }
 
 /**
@@ -479,6 +442,12 @@ void Audio::cleanupOutput()
         alSourceStop(alMainSource);
         alDeleteSources(1, &alMainSource);
 
+        if (alMainBuffer)
+        {
+            alDeleteBuffers(1, &alMainBuffer);
+            alMainBuffer = 0;
+        }
+
         if (!alcMakeContextCurrent(nullptr))
             qWarning("Failed to clear audio context.");
 
@@ -493,6 +462,20 @@ void Audio::cleanupOutput()
     }
 }
 
+void Audio::playMono16SoundCleanup()
+{
+    QMutexLocker locker(&audioLock);
+
+    ALint state;
+    alGetSourcei(alMainSource, AL_SOURCE_STATE, &state);
+    if (state == AL_STOPPED)
+    {
+        alSourcei(alMainSource, AL_BUFFER, AL_NONE);
+        alDeleteBuffers(1, &alMainBuffer);
+        alMainBuffer = 0;
+    }
+}
+
 void Audio::doCapture()
 {
     QMutexLocker lock(&audioLock);

src/audio/audio.h

@@ -105,6 +105,8 @@ private:
     bool initOutput(QString outDevDescr);
     void cleanupInput();
     void cleanupOutput();
+    /// Called after a mono16 sound stopped playing
+    void playMono16SoundCleanup();
     /// Called on the captureTimer events to capture audio
     void doCapture();
 #if defined(QTOX_FILTER_AUDIO) && defined(ALC_LOOPBACK_CAPTURE_SAMPLES)
@@ -118,11 +120,12 @@ private:
     ALCdevice*          alInDev;
     ALfloat             inGain;
     quint32             inSubscriptions;
-    QTimer              captureTimer;
+    QTimer              captureTimer, playMono16Timer;
 
     ALCdevice*          alOutDev;
     ALCcontext*         alOutContext;
     ALuint              alMainSource;
+    ALuint              alMainBuffer;
     bool                outputInitialized;
 
     QList<ALuint>       outSources;