QAudioSink Class

The QAudioSink class provides an interface for sending audio data to an audio output device. 更多...

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

所有成員列錶，包括繼承成員

公共函數

	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
QAudio::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 ()
QAudio::State	state () const
void	stop ()
void	suspend ()
qreal	volume () const

信號

void	stateChanged (QAudio::State state )

詳細描述

You can construct an audio output with the system's default audio output device. It is also possible to create QAudioSink with a specific QAudioDevice 。當創建音頻輸齣時，還應發送 QAudioFormat 用於迴放 (見 QAudioFormat 類描述瞭解細節)。

要播放文件：

開始播放音頻流的問題是隻需調用 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, SIGNAL(stateChanged(QAudio::State)), this, SLOT(handleStateChanged(QAudio::State)));
    audio->start(&sourceFile);
}

文件將開始播放，假定音頻係統和輸齣設備支持它。若運氣不好，校驗怎麼瞭是采用 error () 函數。

文件播放完成後，需要停止設備：

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

At any given time, the QAudioSink will be in one of four states: active, suspended, stopped, or idle. These states are described by the QAudio::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 QAudio::Error enum for a description of the possible errors that are reported. When an error is encountered, the state changes to QAudio::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)
            audio->stop();
            sourceFile.close();
            delete audio;
            break;
        case QAudio::StoppedState:
            // Stopped for other reasons
            if (audio->error() != QAudio::NoError) {
                // Error handling
            }
            break;
        default:
            // ... other cases as appropriate
            break;
    }
}

另請參閱 QAudioSource and QAudioDevice .

成員函數文檔編製

`[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 參數。

`[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 參數。

`[虛擬]` QAudioSink:: ~QAudioSink ()

銷毀此音頻輸齣。

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 ().

另請參閱 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 QAudio::ActiveState or QAudio::IdleState state, otherwise returns zero.

qint64 QAudioSink:: elapsedUSecs () const

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

QAudio::Error QAudioSink:: error () const

返迴錯誤狀態。

QAudioFormat QAudioSink:: format () const

返迴 QAudioFormat 被使用。

bool QAudioSink:: isNull () const

返迴 true 是 QAudioSink instance is null ，否則返迴 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 ()

再繼續處理音頻數據後於 suspend ().

設置 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 QAudio::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.

另請參閱 bufferSize ().

void QAudioSink:: setVolume ( qreal volume )

把輸齣音量設為 volume .

按綫性比例縮放的音量是從 0.0 (無聲) 到 1.0 (全音量)。將鉗製超齣此範圍的值。

默認音量為 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 QAudio::convertVolume () 瞭解更多細節。

另請參閱 volume ().

void QAudioSink:: start ( QIODevice * device )

Starts transferring audio data from the device to the system's audio output. The device 必須已打開以 ReadOnly or ReadWrite 模式。

若 QAudioSink is able to successfully output audio data, state () 返迴 QAudio::ActiveState , error () 返迴 QAudio::NoError 和 stateChanged () 信號發射。

若在此過程中齣現問題， error () 返迴 QAudio::OpenError , state () 返迴 QAudio::StoppedState 和 stateChanged () 信號發射。

另請參閱 QIODevice .

QIODevice *QAudioSink:: start ()

返迴的指針指嚮內部 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： 指針將變為無效，在流被停止或啓動另一個流之後。

若 QAudioSink 能夠訪問係統音頻設備， state () 返迴 QAudio::IdleState , error () 返迴 QAudio::NoError 和 stateChanged () 信號發射。

若在此過程中齣現問題， error () 返迴 QAudio::OpenError , state () 返迴 QAudio::StoppedState 和 stateChanged () 信號發射。

另請參閱 QIODevice .

QAudio::State QAudioSink:: state () const

返迴音頻處理的狀態。

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

此信號被發射當設備 state has changed. This is the current state of the audio output.

void QAudioSink:: stop ()

Stops the audio output, detaching from the system resource.

設置 error () 到 QAudio::NoError , state () 到 QAudio::StoppedState and emit stateChanged () 信號。

void QAudioSink:: suspend ()

Stops processing audio data, preserving buffered audio data.

設置 error () 到 QAudio::NoError , state () 到 QAudio::SuspendedState 並發射 stateChanged () 信號。

qreal QAudioSink:: volume () const

Returns the volume between 0.0 and 1.0 inclusive.

另請參閱 setVolume ().