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** This file is part of the examples of the Qt Toolkit.
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#include <QDebug>
#include <QVBoxLayout>
#include <QAudioOutput>
#include <QAudioDeviceInfo>
#include <QtCore/qmath.h>
#include <QtCore/qendian.h>
#include "audiooutput.h"
const QString AudioTest::PushModeLabel(tr("Enable push mode"));
const QString AudioTest::PullModeLabel(tr("Enable pull mode"));
const QString AudioTest::SuspendLabel(tr("Suspend playback"));
const QString AudioTest::ResumeLabel(tr("Resume playback"));
const int DurationSeconds = 1;
const int ToneFrequencyHz = 600;
const int DataFrequencyHz = 44100;
const int BufferSize = 32768;
Generator::Generator(const QAudioFormat &format,
qint64 durationUs,
int frequency,
QObject *parent)
: QIODevice(parent)
, m_pos(0)
{
generateData(format, durationUs, frequency);
}
Generator::~Generator()
{
}
void Generator::start()
{
open(QIODevice::ReadOnly);
}
void Generator::stop()
{
m_pos = 0;
close();
}
void Generator::generateData(const QAudioFormat &format, qint64 durationUs, int frequency)
{
const int channelBytes = format.sampleSize() / 8;
const int sampleBytes = format.channels() * channelBytes;
qint64 length = (format.frequency() * format.channels() * (format.sampleSize() / 8))
* durationUs / 100000;
Q_ASSERT(length % sampleBytes == 0);
Q_UNUSED(sampleBytes) <span class="comment">// suppress warning in release builds</span>
m_buffer.resize(length);
unsigned char *ptr = reinterpret_cast<unsigned char *>(m_buffer.data());
int sampleIndex = 0;
while (length) {
const qreal x = qSin(2 * M_PI * frequency * qreal(sampleIndex % format.frequency()) / format.frequency());
for (int i=0; i<format.channels(); ++i) {
if (format.sampleSize() == 8 && format.sampleType() == QAudioFormat::UnSignedInt) {
const quint8 value = static_cast<quint8>((1.0 + x) / 2 * 255);
*reinterpret_cast<quint8*>(ptr) = value;
} else if (format.sampleSize() == 8 && format.sampleType() == QAudioFormat::SignedInt) {
const qint8 value = static_cast<qint8>(x * 127);
*reinterpret_cast<quint8*>(ptr) = value;
} else if (format.sampleSize() == 16 && format.sampleType() == QAudioFormat::UnSignedInt) {
quint16 value = static_cast<quint16>((1.0 + x) / 2 * 65535);
if (format.byteOrder() == QAudioFormat::LittleEndian)
qToLittleEndian<quint16>(value, ptr);
else
qToBigEndian<quint16>(value, ptr);
} else if (format.sampleSize() == 16 && format.sampleType() == QAudioFormat::SignedInt) {
qint16 value = static_cast<qint16>(x * 32767);
if (format.byteOrder() == QAudioFormat::LittleEndian)
qToLittleEndian<qint16>(value, ptr);
else
qToBigEndian<qint16>(value, ptr);
}
ptr += channelBytes;
length -= channelBytes;
}
++sampleIndex;
}
}
qint64 Generator::readData(char *data, qint64 len)
{
qint64 total = 0;
while (len - total) {
const qint64 chunk = qMin((m_buffer.size() - m_pos), len - total);
memcpy(data, m_buffer.constData() + m_pos, chunk);
m_pos = (m_pos + chunk) % m_buffer.size();
total += chunk;
}
return total;
}
qint64 Generator::writeData(const char *data, qint64 len)
{
Q_UNUSED(data);
Q_UNUSED(len);
return 0;
}
qint64 Generator::bytesAvailable() const
{
return m_buffer.size() + QIODevice::bytesAvailable();
}
AudioTest::AudioTest()
: m_pullTimer(new QTimer(this))
, m_modeButton(0)
, m_suspendResumeButton(0)
, m_deviceBox(0)
, m_device(QAudioDeviceInfo::defaultOutputDevice())
, m_generator(0)
, m_audioOutput(0)
, m_output(0)
, m_buffer(BufferSize, 0)
{
initializeWindow();
initializeAudio();
}
void AudioTest::initializeWindow()
{
QScopedPointer<QWidget> window(new QWidget);
QScopedPointer<QVBoxLayout> layout(new QVBoxLayout);
m_deviceBox = new QComboBox(this);
foreach (const QAudioDeviceInfo &deviceInfo, QAudioDeviceInfo::availableDevices(QAudio::AudioOutput))
m_deviceBox->addItem(deviceInfo.deviceName(), qVariantFromValue(deviceInfo));
connect(m_deviceBox,SIGNAL(activated(int)),SLOT(deviceChanged(int)));
layout->addWidget(m_deviceBox);
m_modeButton = new QPushButton(this);
m_modeButton->setText(PushModeLabel);
connect(m_modeButton, SIGNAL(clicked()), SLOT(toggleMode()));
layout->addWidget(m_modeButton);
m_suspendResumeButton = new QPushButton(this);
m_suspendResumeButton->setText(SuspendLabel);
connect(m_suspendResumeButton, SIGNAL(clicked()), SLOT(toggleSuspendResume()));
layout->addWidget(m_suspendResumeButton);
window->setLayout(layout.data());
layout.take(); <span class="comment">// ownership transferred</span>
setCentralWidget(window.data());
QWidget *const windowPtr = window.take(); <span class="comment">// ownership transferred</span>
windowPtr->show();
}
void AudioTest::initializeAudio()
{
connect(m_pullTimer, SIGNAL(timeout()), SLOT(pullTimerExpired()));
m_pullMode = true;
m_format.setFrequency(DataFrequencyHz);
m_format.setChannels(1);
m_format.setSampleSize(16);
m_format.setCodec("audio/pcm");
m_format.setByteOrder(QAudioFormat::LittleEndian);
m_format.setSampleType(QAudioFormat::SignedInt);
QAudioDeviceInfo info(QAudioDeviceInfo::defaultOutputDevice());
if (!info.isFormatSupported(m_format)) {
qWarning() << "Default format not supported - trying to use nearest";
m_format = info.nearestFormat(m_format);
}
m_generator = new Generator(m_format, DurationSeconds*1000000, ToneFrequencyHz, this);
createAudioOutput();
}
void AudioTest::createAudioOutput()
{
delete m_audioOutput;
m_audioOutput = 0;
m_audioOutput = new QAudioOutput(m_device, m_format, this);
connect(m_audioOutput, SIGNAL(notify()), SLOT(notified()));
connect(m_audioOutput, SIGNAL(stateChanged(QAudio::State)), SLOT(stateChanged(QAudio::State)));
m_generator->start();
m_audioOutput->start(m_generator);
}
AudioTest::~AudioTest()
{
}
void AudioTest::deviceChanged(int index)
{
m_pullTimer->stop();
m_generator->stop();
m_audioOutput->stop();
m_audioOutput->disconnect(this);
m_device = m_deviceBox->itemData(index).value<QAudioDeviceInfo>();
createAudioOutput();
}
void AudioTest::notified()
{
qWarning() << "bytesFree = " << m_audioOutput->bytesFree()
<< ", " << "elapsedUSecs = " << m_audioOutput->elapsedUSecs()
<< ", " << "processedUSecs = " << m_audioOutput->processedUSecs();
}
void AudioTest::pullTimerExpired()
{
if (m_audioOutput && m_audioOutput->state() != QAudio::StoppedState) {
int chunks = m_audioOutput->bytesFree()/m_audioOutput->periodSize();
while (chunks) {
const qint64 len = m_generator->read(m_buffer.data(), m_audioOutput->periodSize());
if (len)
m_output->write(m_buffer.data(), len);
if (len != m_audioOutput->periodSize())
break;
--chunks;
}
}
}
void AudioTest::toggleMode()
{
m_pullTimer->stop();
m_audioOutput->stop();
if (m_pullMode) {
m_modeButton->setText(PullModeLabel);
m_output = m_audioOutput->start();
m_pullMode = false;
m_pullTimer->start(20);
} else {
m_modeButton->setText(PushModeLabel);
m_pullMode = true;
m_audioOutput->start(m_generator);
}
m_suspendResumeButton->setText(SuspendLabel);
}
void AudioTest::toggleSuspendResume()
{
if (m_audioOutput->state() == QAudio::SuspendedState) {
qWarning() << "status: Suspended, resume()";
m_audioOutput->resume();
m_suspendResumeButton->setText(SuspendLabel);
} else if (m_audioOutput->state() == QAudio::ActiveState) {
qWarning() << "status: Active, suspend()";
m_audioOutput->suspend();
m_suspendResumeButton->setText(ResumeLabel);
} else if (m_audioOutput->state() == QAudio::StoppedState) {
qWarning() << "status: Stopped, resume()";
m_audioOutput->resume();
m_suspendResumeButton->setText(SuspendLabel);
} else if (m_audioOutput->state() == QAudio::IdleState) {
qWarning() << "status: IdleState";
}
}
void AudioTest::stateChanged(QAudio::State state)
{
qWarning() << "state = " << state;
}</pre>
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