QAudioInput 类

QAudioInput 类为从音频输入设备接收音频数据提供接口。更多...

头：	#include <QAudioInput>
qmake:	QT += multimedia
继承：	QObject

所有成员列表，包括继承成员

公共函数

	QAudioInput (const QAudioDeviceInfo & audioDevice , const QAudioFormat & format = QAudioFormat(), QObject * parent = nullptr)
	QAudioInput (const QAudioFormat & format = QAudioFormat(), QObject * parent = nullptr)
virtual	~QAudioInput ()
int	bufferSize () const
int	bytesReady () const
qint64	elapsedUSecs () const
QAudio::Error	error () const
QAudioFormat	format () const
int	notifyInterval () const
int	periodSize () const
qint64	processedUSecs () const
void	reset ()
void	resume ()
void	setBufferSize (int value )
void	setNotifyInterval (int ms )
void	setVolume (qreal volume )
void	start (QIODevice * device )
QIODevice *	start ()
QAudio::State	state () const
void	stop ()
void	suspend ()
qreal	volume () const

信号

void	notify ()
void	stateChanged (QAudio::State state )

详细描述

可以构造音频输入采用系统的默认音频输入设备 . It is also possible to create QAudioInput with a specific QAudioDeviceInfo 。当创建音频输入时，还应发送 QAudioFormat 用于录制 (见 QAudioFormat 类描述了解细节)。

要录制到文件：

QAudioInput 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 QAudioDeviceInfo for a specific device. You also need to pass in the QAudioFormat in which you wish to record.

Starting up the QAudioInput is simply a matter of calling start () 采用 QIODevice opened for writing. For instance, to record to a file, you can:

QFile destinationFile;   // Class member
QAudioInput* audio; // Class member
{
    destinationFile.setFileName("/tmp/test.raw");
    destinationFile.open( QIODevice::WriteOnly | QIODevice::Truncate );
    QAudioFormat format;
    // Set up the desired format, for example:
    format.setSampleRate(8000);
    format.setChannelCount(1);
    format.setSampleSize(8);
    format.setCodec("audio/pcm");
    format.setByteOrder(QAudioFormat::LittleEndian);
    format.setSampleType(QAudioFormat::UnSignedInt);
    QAudioDeviceInfo info = QAudioDeviceInfo::defaultInputDevice();
    if (!info.isFormatSupported(format)) {
        qWarning() << "Default format not supported, trying to use the nearest.";
        format = info.nearestFormat(format);
    }
    audio = new QAudioInput(format, this);
    connect(audio, SIGNAL(stateChanged(QAudio::State)), this, SLOT(handleStateChanged(QAudio::State)));
    QTimer::singleShot(3000, this, SLOT(stopRecording()));
    audio->start(&destinationFile);
    // Records audio for 3000ms
}

This will start recording if the format specified is supported by the input device (you can check this with QAudioDeviceInfo::isFormatSupported (). In case there are any snags, use the error () function to check what went wrong. We stop recording in the stopRecording() 槽。

void AudioInputExample::stopRecording()
{
    audio->stop();
    destinationFile.close();
    delete audio;
}

At any point in time, QAudioInput will be in one of four states: active, suspended, stopped, or idle. These states are specified by the QAudio::State enum. You can request a state change directly through suspend (), resume (), stop (), reset ()，和 start (). The current state is reported by state (). QAudioOutput will also signal you when the state changes ( stateChanged ()).

QAudioInput provides several ways of measuring the time that has passed since the start () of the recording. The 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 QAudioInput has been in.

If an error should occur, you can fetch its reason with error (). The possible error reasons are described by the QAudio::Error enum. The QAudioInput will enter the StoppedState when an error is encountered. Connect to the stateChanged () signal to handle the error:

void AudioInputExample::handleStateChanged(QAudio::State newState)
{
    switch (newState) {
        case QAudio::StoppedState:
            if (audio->error() != QAudio::NoError) {
                // Error handling
            } else {
                // Finished recording
            }
            break;
        case QAudio::ActiveState:
            // Started recording - read from IO device
            break;
        default:
            // ... other cases as appropriate
            break;
    }
}

另请参阅 QAudioOutput and QAudioDeviceInfo .

成员函数文档编制

QAudioInput:: QAudioInput (const QAudioDeviceInfo & audioDevice , const QAudioFormat & format = QAudioFormat(), QObject * parent = nullptr)

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

QAudioInput:: QAudioInput (const QAudioFormat & format = QAudioFormat(), QObject * parent = nullptr)

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

`[signal]` void QAudioInput:: notify ()

This signal is emitted when x ms of audio data has been processed the interval set by setNotifyInterval (x).

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

此信号被发射当设备 state 已改变。

`[虚拟]` QAudioInput:: ~QAudioInput ()

Destroy this audio input.

int QAudioInput:: 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 ().

int QAudioInput:: bytesReady () const

Returns the amount of audio data available to read in bytes.

Note: returned value is only valid while in QAudio::ActiveState or QAudio::IdleState state, otherwise returns zero.

qint64 QAudioInput:: elapsedUSecs () const

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

QAudio::Error QAudioInput:: error () const

返回错误状态。

QAudioFormat QAudioInput:: format () const

返回 QAudioFormat 被使用。

int QAudioInput:: notifyInterval () const

Returns the notify interval in milliseconds.

另请参阅 setNotifyInterval ().

int QAudioInput:: periodSize () const

Returns the period size in bytes.

Note: This is the recommended read size in bytes.

qint64 QAudioInput:: processedUSecs () const

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

void QAudioInput:: reset ()

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

void QAudioInput:: resume ()

Resumes processing audio data after a suspend ().

设置 error () 到 QAudio::NoError . Sets state () 到 QAudio::ActiveState if you previously called start( QIODevice *). Sets state () 到 QAudio::IdleState if you previously called start (). emits stateChanged () 信号。

void QAudioInput:: setBufferSize ( int value )

Sets the audio buffer size to value 字节。

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.

另请参阅 bufferSize ().

void QAudioInput:: setNotifyInterval ( int ms )

Sets the interval for notify () signal to be emitted. This is based on the ms of audio data processed not on actual real-time. The minimum resolution of the timer is platform specific and values should be checked with notifyInterval () to confirm actual value being used.

另请参阅 notifyInterval ().

void QAudioInput:: setVolume ( qreal volume )

Sets the input 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.

If the device does not support adjusting the input volume then volume will be ignored and the input volume will remain at 1.0.

默认音量为 1.0 .

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

另请参阅 volume ().

void QAudioInput:: start ( QIODevice * device )

开始将音频数据从系统的音频输入传输到 device 。 device 必须已打开以 WriteOnly , 追加 or ReadWrite 模式。

若 QAudioInput 能够成功获取音频数据， state () 返回 QAudio::ActiveState or QAudio::IdleState , error () 返回 QAudio::NoError 和 stateChanged () 信号发射。

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

另请参阅 QIODevice .

QIODevice *QAudioInput:: start ()

返回的指针指向内部 QIODevice 用于传输来自系统音频输入的数据。设备已打开且 read() 可以直接从它读取数据。

注意： 指针将变为无效，在流被停止或启动另一个流之后。

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

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

另请参阅 QIODevice .

QAudio::State QAudioInput:: state () const

返回音频处理的状态。

void QAudioInput:: stop ()

Stops the audio input, detaching from the system resource.

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

void QAudioInput:: suspend ()

Stops processing audio data, preserving buffered audio data.

设置 error () 到 QAudio::NoError , state () 到 QAudio::SuspendedState and emit stateChanged () 信号。

qreal QAudioInput:: volume () const

返回输入音量。

If the device does not support adjusting the input volume the returned value will be 1.0.

另请参阅 setVolume ().