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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#include "qaudiosource.h"
#include <QtMultimedia/private/qtmm_alignment_support_p.h>
#include <QtMultimedia/private/qaudiohelpers_p.h>
#include <QtMultimedia/private/qaudiosystem_p.h>
#include <QtMultimedia/private/qplatformaudiodevices_p.h>
#include <QtMultimedia/private/qplatformmediaintegration_p.h>
#include <QtMultimedia/qaudio.h>
#include <QtMultimedia/qaudiodevice.h>
QT_BEGIN_NAMESPACE
/*!
\class QAudioSource
\brief The QAudioSource class provides an interface for receiving audio data from an audio input
device.
\inmodule QtMultimedia
\ingroup multimedia
\ingroup multimedia_audio
You can construct an audio input with the system's
default audio input device. It is also possible to
create QAudioSource with a specific QAudioDevice. When
you create the audio input, you should also send in the
QAudioFormat to be used for the recording (see the QAudioFormat
class description for details).
QAudioSink can be used in two different modes:
\list
\li Using a QIODevice from an application thread
\li Using a callback-based interface from the audio thread
\endlist
\section1 QIODevice interface
QAudioSource lets you record audio with an audio input device. The
default constructor of this class will use the systems default
audio device, but you can also specify a QAudioDevice for a
specific device. You also need to pass in the QAudioFormat in
which you wish to record.
Starting up the QAudioSource is simply a matter of calling start()
with a QIODevice opened for writing. For instance, to record to a
file, you can:
\snippet multimedia-snippets/audio.cpp Audio input class members
\snippet multimedia-snippets/audio.cpp Audio input setup
This will start recording if the format specified is supported by
the input device (you can check this with
QAudioDevice::isFormatSupported(). In case there are any
snags, use the error() function to check what went wrong. We stop
recording in the \c stopRecording() slot.
\snippet multimedia-snippets/audio.cpp Audio input stop recording
At any point in time, QAudioSource will be in one of four states:
active, suspended, stopped, or idle. These states are specified by
the QtAudio::State enum.
QAudioSource provides several ways of measuring the time that has
passed since the start() of the recording. The \c processedUSecs()
function returns the length of the stream in microseconds written,
i.e., it leaves out the times the audio input was suspended or idle.
The elapsedUSecs() function returns the time elapsed since start() was called regardless of
which states the QAudioSource has been in.
\section2 Threading model and buffering
The QIODevice interface is designed to be used from the application thread.
A wait-free ringbuffer is used to communicate to the audio thread. The size
of this ringbuffer can be configured with setBufferSize() and defaults to
250ms. The state of this buffer can be queried with bytesFree(). If the
ringbuffer is full because the application does not read from the QIODevice in time,
the state will change to QtAudio::IdleState and resume to QtAudio::ActiveState
once the application has read data from the QIODevice. Note that this state change will drop
audio data, so you should always read from the QIODevice as fast as possible to avoid dropouts.
\section1 Callback interface
The preferred way to achieve low audio latencies is to use the callback based interface.
It allows you to read audio data directly from the audio device without having to go through
a QIODevice. This is done by calling start() with a callback function that will be called
from the audio thread. This callback function will be called with a QSpan<const SampleType>
whenever the audio backend produces data.
\snippet multimedia-snippets/audio.cpp Audio callback capture class members
\snippet multimedia-snippets/audio.cpp Audio callback capture setup peak meter
Unlike the QIODevice-based interface, the QAudioSource can only be in the states active,
suspendend and stopped. The setBufferSize() API is not available when using the callback,
the size of the callback argument is determined by the audio backend.
\qtmmaudiocallbacksupportednote
\qtmmaudiocallbacknote
\section1 State and error handling
State changes are reported through the stateChanged() signal. You can request a state change
directly through suspend(), resume(), stop(), reset(), and start().
The QAudioSource will enter the \l{QtAudio::}{StoppedState} when an error is encountered.
The \l{QtAudio::Error}{error type} can be retrieved error() function. Please see the
QtAudio::Error enum for a description of the possible errors that are reported. Calling stop()
or reset() will reset the error state to \l{QtAudio::Error}{NoError}.
\snippet multimedia-snippets/audio.cpp Audio input state changed
\sa QAudioSink, QAudioDevice
*/
/*!
Construct a new audio input and attach it to \a parent.
The default audio input device is used with the output
\a format parameters. If \a format is default-initialized,
the format will be set to the preferred format of the audio device.
*/
QAudioSource::QAudioSource(const QAudioFormat &format, QObject *parent)
: QAudioSource({}, format, parent)
{
}
/*!
Construct a new audio input and attach it to \a parent.
The device referenced by \a audioDevice is used with the input
\a format parameters. If \a format is default-initialized,
the format will be set to the preferred format of \a audioDevice.
*/
QAudioSource::QAudioSource(const QAudioDevice &audioDevice, const QAudioFormat &format, QObject *parent):
QObject(parent)
{
d = QPlatformMediaIntegration::instance()->audioDevices()->audioInputDevice(format, audioDevice,
this);
if (d)
connect(d, &QPlatformAudioSource::stateChanged, this, &QAudioSource::stateChanged);
else
qWarning("No audio device detected");
}
/*!
\fn bool QAudioSource::isNull() const
Returns \c true if the audio source is \c null, otherwise returns \c false.
*/
/*!
Destroy this audio input.
*/
QAudioSource::~QAudioSource()
{
delete d;
}
static bool validateFormatAtStart(QPlatformAudioSource *d)
{
if (!d->format().isValid()) {
qWarning() << "QAudioSource::start: QAudioFormat not valid";
d->setError(QAudio::OpenError);
return false;
}
if (!d->isFormatSupported(d->format())) {
qWarning() << "QAudioSource::start: QAudioFormat not supported by QAudioDevice";
d->setError(QAudio::OpenError);
return false;
}
return true;
};
/*!
Starts transferring audio data from the system's audio input to the \a device.
The \a device must have been opened in the \l{QIODevice::WriteOnly}{WriteOnly},
\l{QIODevice::Append}{Append} or \l{QIODevice::ReadWrite}{ReadWrite} modes.
If the QAudioSource is able to successfully get audio data, state() returns
either QtAudio::ActiveState or QtAudio::IdleState, error() returns QtAudio::NoError
and the stateChanged() signal is emitted.
If a problem occurs during this process, error() returns QtAudio::OpenError,
state() returns QtAudio::StoppedState and the stateChanged() signal is emitted.
\sa QIODevice {QAudioSource#Callback interface}{QIODevice interface}
*/
void QAudioSource::start(QIODevice* device)
{
if (!d)
return;
d->setError(QAudio::NoError);
if (!device->isWritable()) {
qWarning() << "QAudioSource::start: QIODevice is not writable";
d->setError(QAudio::OpenError);
return;
}
if (!validateFormatAtStart(d))
return;
d->elapsedTime.start();
d->start(device);
}
/*!
Returns a pointer to the internal QIODevice being used to transfer data from
the system's audio input. The device will already be open and
\l{QIODevice::read()}{read()} can read data directly from it.
\note The pointer will become invalid after the stream is stopped or
if you start another stream.
If the QAudioSource is able to access the system's audio device, state() returns
QtAudio::IdleState, error() returns QtAudio::NoError
and the stateChanged() signal is emitted.
If a problem occurs during this process, error() returns QtAudio::OpenError,
state() returns QtAudio::StoppedState and the stateChanged() signal is emitted.
\sa QIODevice {QAudioSource#Callback interface}{QIODevice interface}
*/
QIODevice* QAudioSource::start()
{
if (!d)
return nullptr;
d->setError(QAudio::NoError);
if (!validateFormatAtStart(d))
return nullptr;
d->elapsedTime.start();
return d->start();
}
/*!
\fn template <typename Callback, QtAudio::if_audio_source_callback<Callback> = true> void QAudioSource::start(Callback &&)
Starts the QAudioSource with a callback function that will be called on a soft-realtime audio
thread. The callback is a callable that takes a QSpan<const SampleType> as an argument,
SampleType has to match the QAudioFormat::SampleFormat of the QAudioSource's format. The span
contains the interleaved audio data.
If the QAudioSource is able to successfully start, error() returns QtAudio::NoError.
If a problem occurs during this process, error() returns QtAudio::OpenError, state() returns
QtAudio::StoppedState and the stateChanged() signal is emitted.
\qtmmaudiocallbacksupportednote
\qtmmaudiocallbacknote
\sa {QAudioSource#Callback interface}{Callback interface}
\since 6.11
*/
template <typename T>
void QAudioSource::startImpl(T &&callback)
{
if (!d)
return;
if (!d->hasCallbackAPI()) {
qWarning() << "QAudioSource::start: Callback API not supported on this platform";
d->setError(QAudio::OpenError);
return;
}
using namespace QtMultimediaPrivate;
if (!validateAudioCallback(callback, format())) {
d->setError(QAudio::OpenError);
return;
}
if (!validateFormatAtStart(d))
return;
d->elapsedTime.start();
d->start(std::forward<T>(callback));
}
void QAudioSource::startABIImpl(QtAudioPrivate::AudioSourceCallback &&callback)
{
return QAudioSource::startImpl(QtMultimediaPrivate::asAudioSourceCallback(std::move(callback)));
}
/*!
Returns the QAudioFormat being used.
*/
QAudioFormat QAudioSource::format() const
{
return d ? d->format() : QAudioFormat();
}
/*!
Stops the audio input, detaching from the system resource.
Sets error() to QtAudio::NoError, state() to QtAudio::StoppedState and
emit stateChanged() signal.
*/
void QAudioSource::stop()
{
if (d)
d->stop();
}
/*!
Drops all audio data in the buffers, resets buffers to zero.
*/
void QAudioSource::reset()
{
if (d)
d->reset();
}
/*!
Stops processing audio data, preserving buffered audio data.
Sets error() to QtAudio::NoError, state() to QtAudio::SuspendedState and
emit stateChanged() signal.
*/
void QAudioSource::suspend()
{
if (d)
d->suspend();
}
/*!
Resumes processing audio data after a suspend().
Sets state() to the state the sink had when suspend() was called. This function does nothing if
the audio sink's state is not QtAudio::SuspendedState.
*/
void QAudioSource::resume()
{
if (d)
d->resume();
}
/*!
Sets the audio buffer size to \a value bytes.
\note This function can be called anytime before start(), calls to this
are ignored after start(). It should not be assumed that the buffer size
set is the actual buffer size used, calling bufferSize() anytime after start()
will return the actual buffer size being used.
The bufferFrameCount() and bufferSize() properties denote the ringbuffer size
when using the QIODevice APIs. The native period size is controlled via setNativePeriodFrameCount().
\sa setBufferFrameCount
*/
void QAudioSource::setBufferSize(qsizetype value)
{
if (d)
d->setBufferSize(value);
}
/*!
Returns the audio buffer size in bytes.
If called before \l start(), returns platform default value.
If called before \c start() but \l setBufferSize() or \l setBufferFrameCount() was called prior, returns
value set by \c setBufferSize() or \c setBufferFrameCount(). If called after \c start(), returns the actual
buffer size being used. This may not be what was set previously by
\c setBufferSize() or \c setBufferFrameCount().
\sa bufferFrameCount
*/
qsizetype QAudioSource::bufferSize() const
{
return d ? d->bufferSize() : 0;
}
/*!
Sets the audio buffer size to \a value in frame count.
\note This function can be called anytime before start(). Calls to this
are ignored after start(). It should not be assumed that the buffer size
set is the actual buffer size used - call bufferFrameCount() anytime
after start() to return the actual buffer size being used.
The bufferFrameCount() and bufferSize() properties denote the ringbuffer size
when using the QIODevice APIs. The native period size is controlled via setNativePeriodFrameCount().
\sa setBufferSize
\since 6.10
*/
void QAudioSource::setBufferFrameCount(qsizetype value)
{
if (d)
setBufferSize(d->format().bytesForFrames(value));
}
/*!
Returns the audio buffer size in frames.
If called before \l start(), returns platform default value.
If called before \c start() but \l setBufferSize() or \l setBufferFrameCount() was called prior, returns
value set by \c setBufferSize() or \c setBufferFrameCount(). If called after \c start(), returns the actual
buffer size being used. This may not be what was set previously by
\c setBufferSize() or \c setBufferFrameCount().
\sa bufferSize
\since 6.10
*/
qsizetype QAudioSource::bufferFrameCount() const
{
return d ? d->format().framesForBytes(bufferSize()) : 0;
}
/*!
Sets the native period frame count to \a frameCount.
Tunes the audio buffer size used by the operating system and hardware. By default (when not set),
the system uses a platform-dependent value, typically 1024 frames (~23ms at 44100 Hz).
Use smaller values (64-256) to reduce latency, or larger values (2048-4096) to reduce the risk of
buffer overruns (dropouts).
Valid values are powers of 2 between 32 and 4096 (inclusive), or -1 to unset. Can only be called
when the audio source is stopped.
Maps to platform-specific settings: \c{kAudioDevicePropertyBufferFrameSize} (macOS),
\c{IAudioClient::bufferDuration} (Windows), \c{PW_KEY_NODE_FORCE_QUANTUM} (PipeWire/Linux),
and \c{AAudioStreamBuilder_setBufferCapacityInFrames} (Android).
\note This is separate from the ringbuffer configured with setBufferSize() or setBufferFrameCount().
\since 6.12
\sa nativePeriodFrameCount
*/
void QAudioSource::setNativePeriodFrameCount(qsizetype frameCount)
{
if (!d)
return;
if (frameCount != -1) {
// Check if stopped
if (state() != QAudio::StoppedState) {
qWarning("QAudioSource::setNativePeriodFrameCount: can only be set when stopped");
return;
}
if (frameCount < 32 || frameCount > 4096
|| !QtMultimediaPrivate::isPowerOfTwo(frameCount)) {
qWarning("QAudioSource::setNativePeriodFrameCount: invalid frame count %lld "
"(must be -1 or a power of 2 between 32 and 4096)",
qint64(frameCount));
return;
}
}
if (frameCount != -1)
d->setNativePeriodFrames(QtMultimediaPrivate::NativePeriodFrames(frameCount));
else
d->setNativePeriodFrames(std::nullopt);
}
/*!
Returns the native period frame count.
Returns -1 if not set, otherwise returns the value previously set with
setNativePeriodFrameCount().
\since 6.12
\sa setNativePeriodFrameCount
*/
qsizetype QAudioSource::nativePeriodFrameCount() const
{
std::optional hwbf = d ? d->nativePeriodFrames() : std::nullopt;
return hwbf ? qsizetype(qToUnderlying(*hwbf)) : qsizetype(-1);
}
/*!
Returns the amount of audio data available to read in bytes.
\note returned value is only valid while in QtAudio::ActiveState or QtAudio::IdleState
state, otherwise returns zero.
\sa framesAvailable
*/
qsizetype QAudioSource::bytesAvailable() const
{
return d ? d->bytesReady() : 0;
}
/*!
Returns the amount of audio data available to read in frames.
Note: returned value is only valid while in QtAudio::ActiveState or QtAudio::IdleState
state, otherwise returns zero.
\sa bytesAvailable
\since 6.10
*/
qsizetype QAudioSource::framesAvailable() const
{
return d ? d->format().framesForBytes(bytesAvailable()) : 0;
}
/*!
Sets the input volume to \a volume.
The volume is scaled linearly from \c 0.0 (silence) to \c 1.0 (full volume). Values outside this
range will be clamped.
If the device does not support adjusting the input
volume then \a volume will be ignored and the input
volume will remain at 1.0.
The default volume is \c 1.0.
\note Adjustments to the volume will change the volume of this audio stream, not the global
volume.
*/
void QAudioSource::setVolume(qreal volume)
{
if (!d)
return;
std::optional<float> newVolume = QAudioHelperInternal::sanitizeVolume(volume, this->volume());
if (newVolume)
d->setVolume(*newVolume);
}
/*!
Returns the input volume.
If the device does not support adjusting the input volume
the returned value will be 1.0.
*/
qreal QAudioSource::volume() const
{
return d ? d->volume() : 1.0;
}
/*!
Returns the amount of audio data processed since start()
was called in microseconds.
*/
qint64 QAudioSource::processedUSecs() const
{
return d ? d->processedUSecs() : 0;
}
/*!
Returns the microseconds since start() was called, including time in Idle and
Suspend states.
*/
qint64 QAudioSource::elapsedUSecs() const
{
return state() == QAudio::StoppedState ? 0 : d->elapsedTime.nsecsElapsed()/1000;
}
/*!
Returns the error state.
*/
QtAudio::Error QAudioSource::error() const
{
return d ? d->error() : QAudio::OpenError;
}
/*!
Returns the state of audio processing.
*/
QtAudio::State QAudioSource::state() const
{
return d ? d->state() : QAudio::StoppedState;
}
/*!
\fn QAudioSource::stateChanged(QtAudio::State state)
This signal is emitted when the device \a state has changed.
\note The QtAudio namespace was named QAudio up to and including Qt 6.6.
String-based connections to this signal have to use \c{QAudio::State} as
the parameter type: \c{connect(source, SIGNAL(stateChanged(QAudio::State)), ...);}
*/
QT_END_NAMESPACE
#include "moc_qaudiosource.cpp"