From e2a4fcbca41d24a0eb6fd8e89a5390e23e96df7a Mon Sep 17 00:00:00 2001
From: VaL Doroshchuk <valbok@gmail.com>
Date: Mon, 22 Jan 2024 18:09:00 +0100
Subject: [PATCH] Set volume to QAVAudioOutput ASAP

---
 src/QtAVPlayer/qavaudiooutput.cpp | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/src/QtAVPlayer/qavaudiooutput.cpp b/src/QtAVPlayer/qavaudiooutput.cpp
index e7ac47c3..354c15f5 100644
--- a/src/QtAVPlayer/qavaudiooutput.cpp
+++ b/src/QtAVPlayer/qavaudiooutput.cpp
@@ -184,10 +184,9 @@ class QAVAudioOutputPrivate : public QIODevice
 
             if (bufferSize > 0)
                 audioOutput->setBufferSize(bufferSize);
+            audioOutput->setVolume(volume);
             audioOutput->start(this);
         }
-
-        audioOutput->setVolume(volume);
     }
 
     void doPlayAudio()
@@ -199,28 +198,35 @@ class QAVAudioOutputPrivate : public QIODevice
 #if QT_VERSION >= QT_VERSION_CHECK(6, 4, 0)
             fmt.setChannelConfig(channelConfig);
 #endif
-            locker.unlock();
             if (fmt.isValid())
                 init(fmt);
+            locker.unlock();
             QCoreApplication::processEvents();
         }
+        QMutexLocker locker(&mutex);
         if (audioOutput) {
             audioOutput->stop();
             audioOutput->deleteLater();
         }
         audioOutput = nullptr;
     }
+
+    void startThreadIfNeeded()
+    {
+        if (!audioPlayFuture.isRunning()) {
+#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
+            audioPlayFuture = QtConcurrent::run(&threadPool, this, &QAVAudioOutputPrivate::doPlayAudio);
+#else
+            audioPlayFuture = QtConcurrent::run(&threadPool, &QAVAudioOutputPrivate::doPlayAudio, this);
+#endif
+        }
+    }
 };
 
 QAVAudioOutput::QAVAudioOutput(QObject *parent)
     : QObject(parent)
     , d_ptr(new QAVAudioOutputPrivate)
 {
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-    d_ptr->audioPlayFuture = QtConcurrent::run(&d_ptr->threadPool, d_ptr.get(), &QAVAudioOutputPrivate::doPlayAudio);
-#else
-    d_ptr->audioPlayFuture = QtConcurrent::run(&d_ptr->threadPool, &QAVAudioOutputPrivate::doPlayAudio, d_ptr.get());
-#endif
 }
 
 QAVAudioOutput::~QAVAudioOutput()
@@ -236,6 +242,8 @@ void QAVAudioOutput::setVolume(qreal v)
     Q_D(QAVAudioOutput);
     QMutexLocker locker(&d->mutex);
     d->volume = v;
+    if (d->audioOutput)
+        d->audioOutput->setVolume(v);
 }
 
 qreal QAVAudioOutput::volume() const
@@ -250,6 +258,8 @@ void QAVAudioOutput::setBufferSize(int bytes)
     Q_D(QAVAudioOutput);
     QMutexLocker locker(&d->mutex);
     d->bufferSize = bytes;
+    if (d->bufferSize > 0 && d->audioOutput)
+        d->audioOutput->setBufferSize(d->bufferSize);
 }
 
 int QAVAudioOutput::bufferSize() const
@@ -283,6 +293,7 @@ bool QAVAudioOutput::play(const QAVAudioFrame &frame)
         return false;
 
     QMutexLocker locker(&d->mutex);
+    d->startThreadIfNeeded();
     d->frames.push_back(frame);
     d->cond.wakeAll();