From 2422d893392d25a94323ea7faf88ae9e8527ce31 Mon Sep 17 00:00:00 2001
From: Val Doroshchuk <valentyn.doroshchuk@qt.io>
Date: Mon, 12 Feb 2018 15:57:07 +0100
Subject: WindowsAudio: Pause playback before reset

When some data has been written to play and waveOutReset is called
some crackling could be heard at the end of playback.

Proposed a fix to pause playback and wait for time of buffers pushed to play.

Task-number: QTBUG-63492
Change-Id: Ieb72c0657eee3dd92a947999d70f366e2bd7f102
Reviewed-by: Maurice Kalinowski <maurice.kalinowski@qt.io>
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>
---
 src/plugins/windowsaudio/qwindowsaudiooutput.cpp | 16 ++++++++++++----
 src/plugins/windowsaudio/qwindowsaudiooutput.h   |  1 +
 2 files changed, 13 insertions(+), 4 deletions(-)

(limited to 'src')

diff --git a/src/plugins/windowsaudio/qwindowsaudiooutput.cpp b/src/plugins/windowsaudio/qwindowsaudiooutput.cpp
index eb4caf128..104055f30 100644
--- a/src/plugins/windowsaudio/qwindowsaudiooutput.cpp
+++ b/src/plugins/windowsaudio/qwindowsaudiooutput.cpp
@@ -291,11 +291,22 @@ bool QWindowsAudioOutput::open()
     return true;
 }
 
+void QWindowsAudioOutput::pauseAndSleep()
+{
+    waveOutPause(hWaveOut);
+    int bitrate = settings.sampleRate() * settings.channelCount() * settings.sampleSize() / 8;
+    // Time of written data.
+    int delay = (buffer_size - bytesFree()) * 1000 / bitrate;
+    Sleep(delay + 10);
+}
+
 void QWindowsAudioOutput::close()
 {
     if(deviceState == QAudio::StoppedState)
         return;
 
+    // Pause playback before reset to avoid uneeded crackling at the end.
+    pauseAndSleep();
     deviceState = QAudio::StoppedState;
     errorState = QAudio::NoError;
     waveOutReset(hWaveOut);
@@ -451,10 +462,7 @@ void QWindowsAudioOutput::resume()
 void QWindowsAudioOutput::suspend()
 {
     if(deviceState == QAudio::ActiveState || deviceState == QAudio::IdleState) {
-        int delay = (buffer_size-bytesFree())*1000/(settings.sampleRate()
-                *settings.channelCount()*(settings.sampleSize()/8));
-        waveOutPause(hWaveOut);
-        Sleep(delay+10);
+        pauseAndSleep();
         deviceState = QAudio::SuspendedState;
         errorState = QAudio::NoError;
         emit stateChanged(deviceState);
diff --git a/src/plugins/windowsaudio/qwindowsaudiooutput.h b/src/plugins/windowsaudio/qwindowsaudiooutput.h
index f25475b02..b71f00e98 100644
--- a/src/plugins/windowsaudio/qwindowsaudiooutput.h
+++ b/src/plugins/windowsaudio/qwindowsaudiooutput.h
@@ -115,6 +115,7 @@ private slots:
     bool deviceReady();
 
 private:
+    void pauseAndSleep();
     QByteArray m_device;
     int bytesAvailable;
     QTime timeStamp;
-- 
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