QAudioSink 类

QAudioSink 类提供将音频数据发送给音频输出设备的接口。更多...

头：	#include <QAudioSink>
CMake:	find_package(Qt6 REQUIRED COMPONENTS Multimedia) target_link_libraries(mytarget PRIVATE Qt6::Multimedia)
qmake:	QT += multimedia
继承：	QObject

所有成员列表，包括继承成员

公共函数

	QAudioSink (const QAudioFormat & format = QAudioFormat(), QObject * parent = nullptr)
	QAudioSink (const QAudioDevice & audioDevice , const QAudioFormat & format = QAudioFormat(), QObject * parent = nullptr)
virtual	~QAudioSink ()
qsizetype	bufferSize () const
qsizetype	bytesFree () const
qint64	elapsedUSecs () const
QtAudio::Error	error () const
QAudioFormat	format () const
bool	isNull () const
qint64	processedUSecs () const
void	reset ()
void	resume ()
void	setBufferSize (qsizetype value )
void	setVolume (qreal volume )
void	start (QIODevice * device )
QIODevice *	start ()
QtAudio::State	state () const
void	stop ()
void	suspend ()
qreal	volume () const

信号

void	stateChanged (QtAudio::State state )

详细描述

可以采用系统默认音频输出设备构建音频输出。也可以创建 QAudioSink 采用特定 QAudioDevice 。当创建音频输出时，还应发送 QAudioFormat 用于回放 (见 QAudioFormat 类描述了解细节)。

要播放文件：

Starting to play an audio stream is simply a matter of calling start () 采用 QIODevice . QAudioSink will then fetch the data it needs from the io device. So playing back an audio file is as simple as:

QFile sourceFile;   // class member.
QAudioSink* audio; // class member.
{
    sourceFile.setFileName("/tmp/test.raw");
    sourceFile.open(QIODevice::ReadOnly);
    QAudioFormat format;
    // Set up the format, eg.
    format.setSampleRate(8000);
    format.setChannelCount(1);
    format.setSampleFormat(QAudioFormat::UInt8);
    QAudioDevice info(QMediaDevices::defaultAudioOutput());
    if (!info.isFormatSupported(format)) {
        qWarning() << "Raw audio format not supported by backend, cannot play audio.";
        return;
    }
    audio = new QAudioSink(format, this);
    connect(audio, QAudioSink::stateChanged, this, &AudioInputExample::handleStateChanged);
    audio->start(&sourceFile);
}

The file will start playing assuming that the audio system and output device support it. If you run out of luck, check what's up with the error () 函数。

After the file has finished playing, we need to stop the device:

void AudioOutputExample::stopAudioOutput()
{
    audio->stop();
    sourceFile.close();
    delete audio;
}

At any given time, the QAudioSink will be in one of four states: active, suspended, stopped, or idle. These states are described by the QtAudio::State enum. State changes are reported through the stateChanged () signal. You can use this signal to, for instance, update the GUI of the application; the mundane example here being changing the state of a play/pause button. You request a state change directly with suspend (), stop (), reset (), resume ()，和 start ().

If an error occurs, you can fetch the error type 采用 error () function. Please see the QtAudio::Error enum for a description of the possible errors that are reported. When QtAudio::UnderrunError is encountered, the state changes to QtAudio::IdleState , when another error is encountered, the state changes to QtAudio::StoppedState . You can check for errors by connecting to the stateChanged () signal:

void AudioOutputExample::handleStateChanged(QAudio::State newState)
{
    switch (newState) {
        case QAudio::IdleState:
            // Finished playing (no more data)
            AudioOutputExample::stopAudioOutput();
            break;
        case QAudio::StoppedState:
            // Stopped for other reasons
            if (audio->error() != QAudio::NoError) {
                // Error handling
            }
            break;
        default:
            // ... other cases as appropriate
            break;
    }
}

另请参阅 QAudioSource and QAudioDevice .

成员函数文档编制

`[explicit]` QAudioSink:: QAudioSink (const QAudioFormat & format = QAudioFormat(), QObject * parent = nullptr)

Construct a new audio output and attach it to parent . The default audio output device is used with the output format 参数。

`[explicit]` QAudioSink:: QAudioSink (const QAudioDevice & audioDevice , const QAudioFormat & format = QAudioFormat(), QObject * parent = nullptr)

Construct a new audio output and attach it to parent . The device referenced by audioDevice is used with the output format 参数。

`[virtual noexcept]` QAudioSink:: ~QAudioSink ()

销毁此音频输出。

This will release any system resources used and free any buffers.

qsizetype QAudioSink:: bufferSize () const

Returns the audio buffer size in bytes.

If called before start (), returns platform default value. If called before start () but setBufferSize () was called prior, returns value set by setBufferSize (). If called after start (), returns the actual buffer size being used. This may not be what was set previously by setBufferSize ().

另请参阅 setBufferSize ().

qsizetype QAudioSink:: bytesFree () const

Returns the number of free bytes available in the audio buffer.

注意： The returned value is only valid while in QtAudio::ActiveState or QtAudio::IdleState state, otherwise returns zero.

qint64 QAudioSink:: elapsedUSecs () const

Returns the microseconds since start () was called, including time in Idle and Suspend states.

QtAudio::Error QAudioSink:: error () const

返回错误状态。

QAudioFormat QAudioSink:: format () const

返回 QAudioFormat 被使用。

bool QAudioSink:: isNull () const

返回 true 是 QAudioSink instance is null ，否则返回 false .

qint64 QAudioSink:: processedUSecs () const

Returns the amount of audio data processed since start () was called (in microseconds).

void QAudioSink:: reset ()

Drops all audio data in the buffers, resets buffers to zero.

void QAudioSink:: resume ()

Resumes processing audio data after a suspend ().

设置 state () to the state the sink had when suspend () was called, and sets error () to QAudioError::NoError. This function does nothing if the audio sink's state is not QtAudio::SuspendedState .

void QAudioSink:: setBufferSize ( qsizetype value )

Sets the audio buffer size to value in bytes.

注意： 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 bufferSize () anytime after start () to return the actual buffer size being used.

另请参阅 bufferSize ().

void QAudioSink:: setVolume ( qreal volume )

Sets the output volume to volume .

The volume is scaled linearly from 0.0 (无声) 到 1.0 (full volume). Values outside this range will be clamped.

默认音量为 1.0 .

注意： Adjustments to the volume will change the volume of this audio stream, not the global volume.

UI volume controls should usually be scaled non-linearly. For example, using a logarithmic scale will produce linear changes in perceived loudness, which is what a user would normally expect from a volume control. See QtAudio::convertVolume () 了解更多细节。

另请参阅 volume ().

void QAudioSink:: start ( QIODevice * device )

Starts transferring audio data from the device to the system's audio output. The device 必须已打开以 ReadOnly or ReadWrite 模式。

若 QAudioSink is able to successfully output audio data, state () 返回 QtAudio::ActiveState , error () 返回 QtAudio::NoError 和 stateChanged () 信号发射。

若在此过程中出现问题， error () 返回 QtAudio::OpenError , state () 返回 QtAudio::StoppedState 和 stateChanged () 信号发射。

另请参阅 QIODevice .

QIODevice *QAudioSink:: start ()

返回的指针指向内部 QIODevice being used to transfer data to the system's audio output. The device will already be open and write () can write data directly to it.

注意： 指针将变为无效，在流被停止或启动另一个流之后。

若 QAudioSink 能够访问系统音频设备， state () 返回 QtAudio::IdleState , error () 返回 QtAudio::NoError 和 stateChanged () 信号发射。

若在此过程中出现问题， error () 返回 QtAudio::OpenError , state () 返回 QtAudio::StoppedState 和 stateChanged () 信号发射。

另请参阅 QIODevice .

QtAudio::State QAudioSink:: state () const

返回音频处理的状态。

`[signal]` void QAudioSink:: stateChanged ( QtAudio::State state )

此信号被发射当设备 state has changed. This is the current state of the audio output.

注意： The QtAudio namespace was named QAudio up to and including Qt 6.6. String-based connections to this signal have to use QAudio::State as the parameter type: connect(source, SIGNAL(stateChanged(QAudio::State)), ...);

void QAudioSink:: stop ()

Stops the audio output, detaching from the system resource.

设置 error () 到 QtAudio::NoError , state () 到 QtAudio::StoppedState and emit stateChanged () 信号。

void QAudioSink:: suspend ()

Stops processing audio data, preserving buffered audio data.

设置 error () 到 QtAudio::NoError , state () 到 QtAudio::SuspendedState 并发射 stateChanged () 信号。

qreal QAudioSink:: volume () const

Returns the volume between 0.0 and 1.0 inclusive.

另请参阅 setVolume ().