The QAudioInput class provides an interface for receiving audio data from an audio input device. More...
#include <QAudioInput>Inherits: QObject.
This class was introduced in Qt Mobility 1.0.
| QAudioInput ( const QAudioFormat & format = QAudioFormat(), QObject * parent = 0 ) | |
| QAudioInput ( const QAudioDeviceInfo & audioDevice, const QAudioFormat & format = QAudioFormat(), QObject * parent = 0 ) | |
| ~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 | start ( QIODevice * device ) |
| QIODevice * | start () |
| QAudio::State | state () const |
| void | stop () |
| void | suspend () |
| void | notify () |
| void | stateChanged ( QAudio::State state ) |
The QAudioInput class provides an interface for receiving audio data from an audio input device.
You can construct an audio input with the system's default audio input device. It is also possible to create QAudioInput with a specific QAudioDeviceInfo. 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).
To record to a file:
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() with a 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 format you want, eg. format.setFrequency(8000); format.setChannels(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 try to use nearest"; format = info.nearestFormat(format); } audio = new QAudioInput(format, this); connect(audio, SIGNAL(stateChanged(QAudio::State)), this, SLOT(stateChanged(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() slot.
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(), and 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::stateChanged(QAudio::State newState) { switch (newState) { case QAudio::StoppedState: if (audio->error() != QAudio::NoError) { // Error handling } else { // Finished recording } break; // ... } }
On Symbian, processes which use this class must have the UserEnvironment platform security capability. If the client process lacks this capability, calls to either overload of start() will fail. This failure is indicated by the QAudioInput object setting its error() value to QAudio::OpenError and then emitting a stateChanged(QAudio::StoppedState) signal.
Platform security capabilities are added via the TARGET.CAPABILITY qmake variable.
See also QAudioOutput and QAudioDeviceInfo.
Construct a new audio input and attach it to parent. The default audio input device is used with the output format parameters.
This function was introduced in Qt Mobility 1.0.
Construct a new audio input and attach it to parent. The device referenced by audioDevice is used with the input format parameters.
This function was introduced in Qt Mobility 1.0.
Destroy this audio input.
Returns the audio buffer size in milliseconds.
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().
This function was introduced in Qt Mobility 1.0.
See also setBufferSize().
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.
This function was introduced in Qt Mobility 1.0.
Returns the microseconds since start() was called, including time in Idle and Suspend states.
This function was introduced in Qt Mobility 1.0.
Returns the error state.
This function was introduced in Qt Mobility 1.0.
Returns the QAudioFormat being used.
This function was introduced in Qt Mobility 1.0.
This signal is emitted when x ms of audio data has been processed the interval set by setNotifyInterval(x).
This function was introduced in Qt Mobility 1.0.
Returns the notify interval in milliseconds.
This function was introduced in Qt Mobility 1.0.
See also setNotifyInterval().
Returns the period size in bytes.
Note: This is the recommended read size in bytes.
This function was introduced in Qt Mobility 1.0.
Returns the amount of audio data processed since start() was called in microseconds.
This function was introduced in Qt Mobility 1.0.
Drops all audio data in the buffers, resets buffers to zero.
This function was introduced in Qt Mobility 1.0.
Resumes processing audio data after a suspend().
Sets error() to QAudio::NoError. Sets state() to QAudio::ActiveState if you previously called start(QIODevice*). Sets state() to QAudio::IdleState if you previously called start(). emits stateChanged() signal.
This function was introduced in Qt Mobility 1.0.
Sets the audio buffer size to value milliseconds.
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.
This function was introduced in Qt Mobility 1.0.
See also bufferSize().
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.
This function was introduced in Qt Mobility 1.0.
See also notifyInterval().
Uses the device as the QIODevice to transfer data. Passing a QIODevice allows the data to be transferred without any extra code. All that is required is to open the QIODevice.
If able to successfully get audio data from the systems audio device the state() is set to either QAudio::ActiveState or QAudio::IdleState, error() is set to QAudio::NoError and the stateChanged() signal is emitted.
If a problem occurs during this process the error() is set to QAudio::OpenError, state() is set to QAudio::StoppedState and stateChanged() signal is emitted.
QAudioInput#Symbian Platform Security Requirements
This function was introduced in Qt Mobility 1.0.
See also QIODevice.
Returns a pointer to the QIODevice being used to handle the data transfer. This QIODevice can be used to read() audio data directly.
If able to access the systems audio device the state() is set to QAudio::IdleState, error() is set to QAudio::NoError and the stateChanged() signal is emitted.
If a problem occurs during this process the error() is set to QAudio::OpenError, state() is set to QAudio::StoppedState and stateChanged() signal is emitted.
QAudioInput#Symbian Platform Security Requirements
This function was introduced in Qt Mobility 1.0.
See also QIODevice.
Returns the state of audio processing.
This function was introduced in Qt Mobility 1.0.
This signal is emitted when the device state has changed.
This function was introduced in Qt Mobility 1.0.
Stops the audio input, detaching from the system resource.
Sets error() to QAudio::NoError, state() to QAudio::StoppedState and emit stateChanged() signal.
This function was introduced in Qt Mobility 1.0.
Stops processing audio data, preserving buffered audio data.
Sets error() to QAudio::NoError, state() to QAudio::SuspendedState and emit stateChanged() signal.
This function was introduced in Qt Mobility 1.0.