PulseAudio: change the way volume is applied.

We used to change the PulseAudio sink input volume. Doing so had
some potential unwanted side effects depending on the PulseAudio server
configuration. When flat volumes were enabled, it would affect the
global system volume. It could also affect the volume of other streams
having the same audio role.
Volumes in Qt Multimedia are supposed to be relative to the application
volume and should not affect anything else than the object on which it
was changed. To guarantee that, PulseAudio volume APIs are not used
anymore. Instead, software-based volume attenuation is applied on the
audio samples before being passed to PulseAudio.

Applies to QSoundEffect, QAudioOutput and QAudioInput.

Task-number: QTBUG-40823
Task-number: QTBUG-49461
Change-Id: I690716976bda8fe666969ca2cbdf6d8d0b419733
Reviewed-by: Christian Stromme <christian.stromme@theqtcompany.com>

2 files changed, 57 insertions, 170 deletions

diff --git a/src/multimedia/audio/qsoundeffect_pulse_p.cpp b/src/multimedia/audio/qsoundeffect_pulse_p.cpp
index ecc42cac5..43d4a6cb0 100644
--- a/src/multimedia/audio/qsoundeffect_pulse_p.cpp
+++ b/src/multimedia/audio/qsoundeffect_pulse_p.cpp
@@ -49,10 +49,7 @@
 
 #include "qsoundeffect_pulse_p.h"
 
-#if defined(Q_WS_MAEMO_6) || defined(NEMO_AUDIO)
-#include <pulse/ext-stream-restore.h>
-#endif
-
+#include <private/qaudiohelpers_p.h>
 #include <private/qmediaresourcepolicy_p.h>
 #include <private/qmediaresourceset_p.h>
 
@@ -124,26 +121,9 @@ public:
         return m_context;
     }
 
-    inline pa_cvolume * calcVolume(pa_cvolume *dest, int soundEffectVolume)
-    {
-        pa_volume_t v = m_vol * soundEffectVolume / 100;
-        for (int i = 0; i < dest->channels; ++i)
-            dest->values[i] = v;
-        return dest;
-    }
-
-    void updateStatus(const pa_cvolume& volume)
-    {
-        if (m_vol != pa_cvolume_max(&volume)) {
-            m_vol = pa_cvolume_max(&volume);
-            emit volumeChanged();
-        }
-    }
-
 Q_SIGNALS:
     void contextReady();
     void contextFailed();
-    void volumeChanged();
 
 private Q_SLOTS:
     void onContextFailed()
@@ -158,8 +138,6 @@ private Q_SLOTS:
 
     void prepare()
     {
-        m_vol = PA_VOLUME_NORM;
-
         m_context = 0;
         m_mainLoop = pa_threaded_mainloop_new();
         if (m_mainLoop == 0) {
@@ -232,11 +210,6 @@ private:
             case PA_CONTEXT_SETTING_NAME:
                 break;
             case PA_CONTEXT_READY:
-    #if defined(Q_WS_MAEMO_6) || defined(NEMO_AUDIO)
-                pa_ext_stream_restore_read(c, &stream_restore_info_callback, self);
-                pa_ext_stream_restore_set_subscribe_cb(c, &stream_restore_monitor_callback, self);
-                pa_ext_stream_restore_subscribe(c, 1, 0, self);
-    #endif
                 QMetaObject::invokeMethod(self, "contextReady", Qt::QueuedConnection);
                 break;
             case PA_CONTEXT_FAILED:
@@ -247,37 +220,6 @@ private:
         }
     }
 
-#if defined(Q_WS_MAEMO_6) || defined(NEMO_AUDIO)
-
-    static void stream_restore_monitor_callback(pa_context *c, void *userdata)
-    {
-        PulseDaemon *self = reinterpret_cast<PulseDaemon*>(userdata);
-        pa_ext_stream_restore_read(c, &stream_restore_info_callback, self);
-    }
-
-    static void stream_restore_info_callback(pa_context *c,
-            const pa_ext_stream_restore_info *info,
-            int eol, void *userdata)
-    {
-        Q_UNUSED(c)
-
-        PulseDaemon *self = reinterpret_cast<PulseDaemon*>(userdata);
-
-        if (!eol) {
-            if (QString(info->name).startsWith(QLatin1String("sink-input-by-media-role:x-maemo"))) {
-#ifdef QT_PA_DEBUG
-                qDebug() << "x-maemo volume =(" << info->volume.values[0] * 100 / PA_VOLUME_NORM << ","
-                         << info->volume.values[1] * 100 / PA_VOLUME_NORM << "), "
-                         << "mute = " << info->mute;
-#endif
-                self->updateStatus(info->volume);
-            }
-        }
-    }
-#endif
-
-    pa_volume_t m_vol;
-
     bool m_prepared;
     pa_context *m_context;
     pa_threaded_mainloop *m_mainLoop;
@@ -385,9 +327,6 @@ QSoundEffectPrivate::QSoundEffectPrivate(QObject* parent):
     m_sample(0),
     m_position(0),
     m_resourcesAvailable(false)
-#if defined(Q_WS_MAEMO_6) || defined(NEMO_AUDIO)
-    , m_customVolume(false)
-#endif
 {
     m_ref = new QSoundEffectRef(this);
     pa_sample_spec_init(&m_pulseSpec);
@@ -538,60 +477,32 @@ void QSoundEffectPrivate::setLoopCount(int loopCount)
 
 qreal QSoundEffectPrivate::volume() const
 {
+    QReadLocker locker(&m_volumeLock);
     return m_volume;
 }
 
 void QSoundEffectPrivate::setVolume(qreal volume)
 {
-#if defined(Q_WS_MAEMO_6) || defined(NEMO_AUDIO)
-    m_customVolume = true;
-#endif
-    m_volume = volume;
-    emit volumeChanged();
-    updateVolume();
-}
+    QWriteLocker locker(&m_volumeLock);
 
-void QSoundEffectPrivate::updateVolume()
-{
-    if (m_sinkInputId < 0)
+    if (qFuzzyCompare(m_volume, volume))
         return;
-#if defined(Q_WS_MAEMO_6) || defined(NEMO_AUDIO)
-    if (!m_customVolume)
-        return;
-#endif
-    PulseDaemonLocker locker;
-    pa_cvolume volume;
-    volume.channels = m_pulseSpec.channels;
-    if (pulseDaemon()->context())
-        pa_operation_unref(pa_context_set_sink_input_volume(pulseDaemon()->context(), m_sinkInputId, pulseDaemon()->calcVolume(&volume, qRound(m_volume * 100)), setvolume_callback, m_ref->getRef()));
-    Q_ASSERT(pa_cvolume_valid(&volume));
-#ifdef QT_PA_DEBUG
-    qDebug() << this << "updateVolume =" << pa_cvolume_max(&volume);
-#endif
+
+    m_volume = qBound(qreal(0), volume, qreal(1));
+    emit volumeChanged();
 }
 
 bool QSoundEffectPrivate::isMuted() const
 {
+    QReadLocker locker(&m_volumeLock);
     return m_muted;
 }
 
 void QSoundEffectPrivate::setMuted(bool muted)
 {
+    QWriteLocker locker(&m_volumeLock);
     m_muted = muted;
     emit mutedChanged();
-    updateMuted();
-}
-
-void QSoundEffectPrivate::updateMuted()
-{
-    if (m_sinkInputId < 0)
-        return;
-    PulseDaemonLocker locker;
-    if (pulseDaemon()->context())
-        pa_operation_unref(pa_context_set_sink_input_mute(pulseDaemon()->context(), m_sinkInputId, m_muted, setmuted_callback, m_ref->getRef()));
-#ifdef QT_PA_DEBUG
-    qDebug() << this << "updateMuted = " << m_muted;
-#endif
 }
 
 bool QSoundEffectPrivate::isLoaded() const
@@ -801,7 +712,6 @@ void QSoundEffectPrivate::unloadPulseStream()
         pa_stream_set_underflow_callback(m_pulseStream, 0, 0);
         pa_stream_disconnect(m_pulseStream);
         pa_stream_unref(m_pulseStream);
-        disconnect(pulseDaemon(), SIGNAL(volumeChanged()), this, SLOT(updateVolume()));
         disconnect(pulseDaemon(), SIGNAL(contextFailed()), this, SLOT(contextFailed()));
         m_pulseStream = 0;
         m_reloadCategory = false; // category will be reloaded when we connect anyway
@@ -822,11 +732,8 @@ void QSoundEffectPrivate::prepare()
              << "actual writeBytes =" << writeBytes
              << "m_playQueued =" << m_playQueued;
 #endif
-    m_position = int(writeBytes);
-    if (pa_stream_write(m_pulseStream, reinterpret_cast<void *>(const_cast<char*>(m_sample->data().data())), writeBytes,
-                        stream_write_done_callback, 0, PA_SEEK_RELATIVE) != 0) {
-        qWarning("QSoundEffect(pulseaudio): pa_stream_write, error = %s", pa_strerror(pa_context_errno(pulseDaemon()->context())));
-    }
+    m_position = writeToStream(m_sample->data().data(), writeBytes);
+
     if (m_playQueued) {
         m_playQueued = false;
         setLoopsRemaining(m_loopCount);
@@ -854,15 +761,13 @@ void QSoundEffectPrivate::uploadSample()
         }
     }
 
-    int writtenBytes = 0;
     int writableSize = int(pa_stream_writable_size(m_pulseStream));
     int firstPartLength = qMin(m_sample->data().size() - m_position, writableSize);
-    if (pa_stream_write(m_pulseStream, reinterpret_cast<void *>(const_cast<char*>(m_sample->data().data()) + m_position),
-                        firstPartLength, stream_write_done_callback, 0, PA_SEEK_RELATIVE) != 0) {
-        qWarning("QSoundEffect(pulseaudio): pa_stream_write, error = %s", pa_strerror(pa_context_errno(pulseDaemon()->context())));
-    }
-    writtenBytes = firstPartLength;
-    m_position += firstPartLength;
+
+    int writtenBytes = writeToStream(m_sample->data().data() + m_position,
+                                     firstPartLength);
+
+    m_position += writtenBytes;
     if (m_position == m_sample->data().size()) {
         m_position = 0;
         if (m_runningCount > 0)
@@ -871,11 +776,8 @@ void QSoundEffectPrivate::uploadSample()
         {
             while (writtenBytes < writableSize) {
                 int writeSize = qMin(writableSize - writtenBytes, m_sample->data().size());
-                if (pa_stream_write(m_pulseStream, reinterpret_cast<void *>(const_cast<char*>(m_sample->data().data())),
-                                    writeSize, stream_write_done_callback, 0, PA_SEEK_RELATIVE) != 0) {
-                    qWarning("QSoundEffect(pulseaudio): pa_stream_write, error = %s", pa_strerror(pa_context_errno(pulseDaemon()->context())));
-                }
-                writtenBytes += writeSize;
+                writtenBytes += writeToStream(m_sample->data().data(), writeSize);
+
                 if (writeSize < m_sample->data().size()) {
                     m_position = writeSize;
                     break;
@@ -893,6 +795,39 @@ void QSoundEffectPrivate::uploadSample()
 #endif
 }
 
+int QSoundEffectPrivate::writeToStream(const void *data, int size)
+{
+    m_volumeLock.lockForRead();
+    qreal volume = m_muted ? 0 : m_volume;
+    m_volumeLock.unlock();
+    pa_free_cb_t writeDoneCb = stream_write_done_callback;
+
+    if (volume < 1.0f) {
+        // Don't use PulseAudio volume, as it might affect all other streams of the same category
+        // or even affect the system volume if flat volumes are enabled
+        void *dest = NULL;
+        size_t nbytes = size;
+        if (pa_stream_begin_write(m_pulseStream, &dest, &nbytes) < 0) {
+            qWarning("QSoundEffect(pulseaudio): pa_stream_begin_write, error = %s",
+                     pa_strerror(pa_context_errno(pulseDaemon()->context())));
+            return 0;
+        }
+
+        size = int(nbytes);
+        QAudioHelperInternal::qMultiplySamples(volume, m_sample->format(), data, dest, size);
+        data = dest;
+        writeDoneCb = NULL;
+    }
+
+    if (pa_stream_write(m_pulseStream, data, size, writeDoneCb, 0, PA_SEEK_RELATIVE) < 0) {
+        qWarning("QSoundEffect(pulseaudio): pa_stream_write, error = %s",
+                 pa_strerror(pa_context_errno(pulseDaemon()->context())));
+        return 0;
+    }
+
+    return size;
+}
+
 void QSoundEffectPrivate::playSample()
 {
 #ifdef QT_PA_DEBUG
@@ -939,8 +874,6 @@ void QSoundEffectPrivate::streamReady()
 #endif
     PulseDaemonLocker locker;
     m_sinkInputId =  pa_stream_get_index(m_pulseStream);
-    updateMuted();
-    updateVolume();
 #ifdef QT_PA_DEBUG
     const pa_buffer_attr *realBufAttr = pa_stream_get_buffer_attr(m_pulseStream);
     qDebug() << this << "m_sinkInputId =" << m_sinkInputId
@@ -966,7 +899,6 @@ void QSoundEffectPrivate::createPulseStream()
     pa_stream *stream = pa_stream_new_with_proplist(pulseDaemon()->context(), m_name.constData(), &m_pulseSpec, 0, propList);
     pa_proplist_free(propList);
 
-    connect(pulseDaemon(), SIGNAL(volumeChanged()), this, SLOT(updateVolume()));
     connect(pulseDaemon(), SIGNAL(contextFailed()), this, SLOT(contextFailed()));
 
     if (stream == 0) {
@@ -994,9 +926,7 @@ void QSoundEffectPrivate::createPulseStream()
 #else
     if (pa_stream_connect_playback(m_pulseStream, 0, 0,
 #endif
-                                   m_muted ? pa_stream_flags_t(PA_STREAM_START_MUTED | PA_STREAM_START_CORKED)
-                                           : pa_stream_flags_t(PA_STREAM_START_UNMUTED | PA_STREAM_START_CORKED),
-                                   0, 0) < 0) {
+                                   PA_STREAM_START_CORKED, 0, 0) < 0) {
         qWarning("QSoundEffect(pulseaudio): Failed to connect stream, error = %s",
                  pa_strerror(pa_context_errno(pulseDaemon()->context())));
     }
@@ -1115,46 +1045,6 @@ void QSoundEffectPrivate::stream_adjust_prebuffer_callback(pa_stream *s, int suc
     QMetaObject::invokeMethod(self, "streamReady", Qt::QueuedConnection);
 }
 
-void QSoundEffectPrivate::setvolume_callback(pa_context *c, int success, void *userdata)
-{
-#ifdef QT_PA_DEBUG
-    qDebug() << "setvolume_callback";
-#endif
-    Q_UNUSED(c);
-    Q_UNUSED(userdata);
-    QSoundEffectRef *ref = reinterpret_cast<QSoundEffectRef*>(userdata);
-    QSoundEffectPrivate *self = ref->soundEffect();
-    ref->release();
-    if (!self)
-        return;
-#ifdef QT_PA_DEBUG
-    qDebug() << self << "setvolume_callback";
-#endif
-    if (!success) {
-        qWarning("QSoundEffect(pulseaudio): faild to set volume");
-    }
-}
-
-void QSoundEffectPrivate::setmuted_callback(pa_context *c, int success, void *userdata)
-{
-#ifdef QT_PA_DEBUG
-    qDebug() << "setmuted_callback";
-#endif
-    Q_UNUSED(c);
-    Q_UNUSED(userdata);
-    QSoundEffectRef *ref = reinterpret_cast<QSoundEffectRef*>(userdata);
-    QSoundEffectPrivate *self = ref->soundEffect();
-    ref->release();
-    if (!self)
-        return;
-#ifdef QT_PA_DEBUG
-    qDebug() << self << "setmuted_callback";
-#endif
-    if (!success) {
-        qWarning("QSoundEffect(pulseaudio): faild to set muted");
-    }
-}
-
 void QSoundEffectPrivate::stream_underrun_callback(pa_stream *s, void *userdata)
 {
     Q_UNUSED(s);
diff --git a/src/multimedia/audio/qsoundeffect_pulse_p.h b/src/multimedia/audio/qsoundeffect_pulse_p.h
index 9b3564cc9..0f16b98a2 100644
--- a/src/multimedia/audio/qsoundeffect_pulse_p.h
+++ b/src/multimedia/audio/qsoundeffect_pulse_p.h
@@ -50,6 +50,7 @@
 
 #include <QtCore/qobject.h>
 #include <QtCore/qdatetime.h>
+#include <QtCore/qreadwritelock.h>
 #include <qmediaplayer.h>
 #include <pulse/pulseaudio.h>
 #include "qsamplecache_p.h"
@@ -111,8 +112,6 @@ private Q_SLOTS:
     void prepare();
     void streamReady();
     void emptyComplete(void *stream);
-    void updateVolume();
-    void updateMuted();
 
     void handleAvailabilityChanged(bool available);
 
@@ -124,6 +123,8 @@ private:
     void createPulseStream();
     void unloadPulseStream();
 
+    int writeToStream(const void *data, int size);
+
     void setPlaying(bool playing);
     void setStatus(QSoundEffect::Status status);
     void setLoopsRemaining(int loopsRemaining);
@@ -136,8 +137,6 @@ private:
     static void stream_write_done_callback(void *p);
     static void stream_adjust_prebuffer_callback(pa_stream *s, int success, void *userdata);
     static void stream_reset_buffer_callback(pa_stream *s, int success, void *userdata);
-    static void setvolume_callback(pa_context *c, int success, void *userdata);
-    static void setmuted_callback(pa_context *c, int success, void *userdata);
 
     pa_stream *m_pulseStream;
     int        m_sinkInputId;
@@ -165,11 +164,9 @@ private:
 
     bool m_resourcesAvailable;
 
-    QMediaPlayerResourceSetInterface *m_resources;
+    mutable QReadWriteLock m_volumeLock;
 
-#if defined(Q_WS_MAEMO_6) || defined(NEMO_AUDIO)
-    bool m_customVolume;
-#endif
+    QMediaPlayerResourceSetInterface *m_resources;
 };
 
 QT_END_NAMESPACE