plugin: async audio processing

plugin/src/Caelestia/audioprovider.cpp

@@ -6,39 +6,49 @@
 #include <QIODevice>
 #include <QMediaDevices>
 #include <QObject>
+#include <QThread>
 #include <cstddef>
 #include <cstdint>
 
 namespace caelestia {
 
-AudioProvider::AudioProvider(int sampleRate, int hopSize, QObject* parent)
-    : Service(parent)
-    , m_hopSize(hopSize) {
+AudioWorker::AudioWorker(int sampleRate, int hopSize, QObject* parent)
+    : QObject(parent)
+    , m_sampleRate(sampleRate)
+    , m_hopSize(hopSize)
+    , m_source(nullptr)
+    , m_device(nullptr) {}
+
+void AudioWorker::init() {
     QAudioFormat format;
-    format.setSampleRate(sampleRate);
+    format.setSampleRate(m_sampleRate);
     format.setChannelCount(1);
     format.setSampleFormat(QAudioFormat::Int16);
 
     m_source = new QAudioSource(QMediaDevices::defaultAudioInput(), format, this);
-    connect(m_source, &QAudioSource::stateChanged, this, &AudioProvider::handleStateChanged);
+    connect(m_source, &QAudioSource::stateChanged, this, &AudioWorker::handleStateChanged);
 };
 
-AudioProvider::~AudioProvider() {
+AudioWorker::~AudioWorker() {
     m_source->stop();
     delete m_source;
 }
 
-void AudioProvider::start() {
+void AudioWorker::start() {
+    if (!m_source) {
+        return;
+    }
+
     m_device = m_source->start();
-    connect(m_device, &QIODevice::readyRead, this, &AudioProvider::processData);
+    connect(m_device, &QIODevice::readyRead, this, &AudioWorker::processData);
 }
 
-void AudioProvider::stop() {
+void AudioWorker::stop() {
     m_source->stop();
     m_device = nullptr;
 }
 
-template <typename T> void AudioProvider::process(T* outBuf) {
+template <typename T> void AudioWorker::process(T* outBuf) {
     const QByteArray data = m_device->readAll();
     const int16_t* samples = reinterpret_cast<const int16_t*>(data.constData());
     const size_t count = static_cast<size_t>(data.size()) / sizeof(int16_t);
@@ -51,23 +61,23 @@ template <typename T> void AudioProvider::process(T* outBuf) {
         }
     }
 }
-template void AudioProvider::process(float* outBuf);
-template void AudioProvider::process(double* outBuf);
+template void AudioWorker::process(float* outBuf);
+template void AudioWorker::process(double* outBuf);
 
-void AudioProvider::handleStateChanged(QtAudio::State state) const {
+void AudioWorker::handleStateChanged(QtAudio::State state) const {
     if (state == QtAudio::StoppedState && m_source->error() != QtAudio::NoError) {
         switch (m_source->error()) {
         case QtAudio::OpenError:
-            qWarning() << "AudioProvider: failed to open audio device";
+            qWarning() << "AudioWorker: failed to open audio device";
             break;
         case QtAudio::IOError:
-            qWarning() << "AudioProvider: an error occurred during read/write of audio device";
+            qWarning() << "AudioWorker: an error occurred during read/write of audio device";
             break;
         case QtAudio::UnderrunError:
-            qWarning() << "AudioProvider: audio data is not being fed to audio device fast enough";
+            qWarning() << "AudioWorker: audio data is not being fed to audio device fast enough";
             break;
         case QtAudio::FatalError:
-            qCritical() << "AudioProvider: fatal error in audio device";
+            qCritical() << "AudioWorker: fatal error in audio device";
             break;
         default:
             break;
@@ -75,4 +85,44 @@ void AudioProvider::handleStateChanged(QtAudio::State state) const {
     }
 }
 
+AudioProvider::AudioProvider(QObject* parent)
+    : Service(parent)
+    , m_worker(nullptr)
+    , m_thread(nullptr) {}
+
+AudioProvider::~AudioProvider() {
+    if (m_thread) {
+        m_thread->quit();
+        m_thread->wait();
+    }
+}
+
+void AudioProvider::init() {
+    if (!m_worker) {
+        qWarning() << "AudioProvider::init: attempted to init with no worker set";
+        return;
+    }
+
+    m_thread = new QThread(this);
+    m_worker->moveToThread(m_thread);
+
+    connect(m_thread, &QThread::started, m_worker, &AudioWorker::init);
+    connect(m_thread, &QThread::finished, m_worker, &AudioWorker::deleteLater);
+    connect(m_thread, &QThread::finished, m_thread, &QThread::deleteLater);
+
+    m_thread->start();
+}
+
+void AudioProvider::start() {
+    if (m_worker) {
+        QMetaObject::invokeMethod(m_worker, "start", Qt::QueuedConnection);
+    }
+}
+
+void AudioProvider::stop() {
+    if (m_worker) {
+        QMetaObject::invokeMethod(m_worker, "stop", Qt::QueuedConnection);
+    }
+}
+
 } // namespace caelestia

plugin/src/Caelestia/audioprovider.hpp

@@ -4,18 +4,22 @@
 #include <QAudioSource>
 #include <QIODevice>
 #include <QObject>
+#include <QThread>
 #include <qqmlintegration.h>
 
 namespace caelestia {
 
-class AudioProvider : public Service {
+class AudioWorker : public QObject {
     Q_OBJECT
 
 public:
-    explicit AudioProvider(int sampleRate = 44100, int hopSize = 512, QObject* parent = nullptr);
-    ~AudioProvider();
+    explicit AudioWorker(int sampleRate = 44100, int hopSize = 512, QObject* parent = nullptr);
+    ~AudioWorker();
+
+    void init();
 
 protected:
+    int m_sampleRate;
     int m_hopSize;
 
     template <typename T> void process(T* outBuf);
@@ -24,8 +28,8 @@ private:
     QAudioSource* m_source;
     QIODevice* m_device;
 
-    void start() override;
-    void stop() override;
+    Q_INVOKABLE void start();
+    Q_INVOKABLE void stop();
 
     void handleStateChanged(QtAudio::State state) const;
 
@@ -33,4 +37,23 @@ private:
     virtual void consumeData() = 0;
 };
 
+class AudioProvider : public Service {
+    Q_OBJECT
+
+public:
+    explicit AudioProvider(QObject* parent = nullptr);
+    ~AudioProvider();
+
+protected:
+    AudioWorker* m_worker;
+
+    void init();
+
+private:
+    QThread* m_thread;
+
+    void start() override;
+    void stop() override;
+};
+
 } // namespace caelestia

plugin/src/Caelestia/beattracker.cpp

@@ -6,33 +6,46 @@
 
 namespace caelestia {
 
-BeatTracker::BeatTracker(uint_t sampleRate, uint_t hopSize, QObject* parent)
-    : AudioProvider(static_cast<int>(sampleRate), static_cast<int>(hopSize), parent)
+BeatWorker::BeatWorker(uint_t sampleRate, uint_t hopSize, QObject* parent)
+    : AudioWorker(static_cast<int>(sampleRate), static_cast<int>(hopSize), parent)
     , m_tempo(new_aubio_tempo("default", 1024, hopSize, sampleRate))
     , m_in(new_fvec(hopSize))
-    , m_out(new_fvec(2))
-    , m_bpm(120) {};
+    , m_out(new_fvec(2)) {};
 
-BeatTracker::~BeatTracker() {
+BeatWorker::~BeatWorker() {
     del_aubio_tempo(m_tempo);
     del_fvec(m_in);
     del_fvec(m_out);
 }
 
+void BeatWorker::processData() {
+    process(m_in->data);
+}
+
+void BeatWorker::consumeData() {
+    aubio_tempo_do(m_tempo, m_in, m_out);
+    if (m_out->data[0] != 0.0f) {
+        emit beat(aubio_tempo_get_bpm(m_tempo));
+    }
+}
+
+BeatTracker::BeatTracker(uint_t sampleRate, uint_t hopSize, QObject* parent)
+    : AudioProvider(parent)
+    , m_bpm(120) {
+    m_worker = new BeatWorker(sampleRate, hopSize, this);
+    init();
+
+    connect(static_cast<BeatWorker*>(m_worker), &BeatWorker::beat, this, &BeatTracker::updateBpm);
+}
+
 smpl_t BeatTracker::bpm() const {
     return m_bpm;
 }
 
-void BeatTracker::processData() {
-    process(m_in->data);
-}
-
-void BeatTracker::consumeData() {
-    aubio_tempo_do(m_tempo, m_in, m_out);
-    if (m_out->data[0] != 0.0f) {
-        m_bpm = aubio_tempo_get_bpm(m_tempo);
+void BeatTracker::updateBpm(smpl_t bpm) {
+    if (!qFuzzyCompare(bpm + 1.0f, m_bpm + 1.0f)) {
+        m_bpm = bpm;
         emit bpmChanged();
-        emit beat(m_bpm);
     }
 }
 

plugin/src/Caelestia/beattracker.hpp

@@ -7,6 +7,25 @@
 
 namespace caelestia {
 
+class BeatWorker : public AudioWorker {
+    Q_OBJECT
+
+public:
+    explicit BeatWorker(uint_t sampleRate = 44100, uint_t hopSize = 512, QObject* parent = nullptr);
+    ~BeatWorker();
+
+signals:
+    void beat(smpl_t bpm);
+
+private:
+    aubio_tempo_t* m_tempo;
+    fvec_t* m_in;
+    fvec_t* m_out;
+
+    void processData() override;
+    void consumeData() override;
+};
+
 class BeatTracker : public AudioProvider {
     Q_OBJECT
     QML_ELEMENT
@@ -16,7 +35,6 @@ class BeatTracker : public AudioProvider {
 
 public:
     explicit BeatTracker(uint_t sampleRate = 44100, uint_t hopSize = 512, QObject* parent = nullptr);
-    ~BeatTracker();
 
     [[nodiscard]] smpl_t bpm() const;
 
@@ -25,14 +43,9 @@ signals:
     void beat(smpl_t bpm);
 
 private:
-    aubio_tempo_t* m_tempo;
-    fvec_t* m_in;
-    fvec_t* m_out;
-
     smpl_t m_bpm;
 
-    void processData() override;
-    void consumeData() override;
+    void updateBpm(smpl_t bpm);
 };
 
 } // namespace caelestia