QAudioInput¶
The
QAudioInput
class provides an interface for receiving audio data from an audio input device. More…
Synopsis¶
Functions¶
def
bufferSize
()def
bytesReady
()def
elapsedUSecs
()def
error
()def
format
()def
notifyInterval
()def
periodSize
()def
processedUSecs
()def
reset
()def
resume
()def
setBufferSize
(bytes)def
setNotifyInterval
(milliSeconds)def
setVolume
(volume)def
start
()def
start
(device)def
state
()def
stop
()def
suspend
()def
volume
()
Signals¶
def
notify
()def
stateChanged
(state)
Detailed Description¶
You can construct an audio input with the system’s
default audio input device
. It is also possible to createQAudioInput
with a specificQAudioDeviceInfo
. When you create the audio input, you should also send in theQAudioFormat
to be used for the recording (see theQAudioFormat
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 aQAudioDeviceInfo
for a specific device. You also need to pass in theQAudioFormat
in which you wish to record.Starting up the
QAudioInput
is simply a matter of callingstart()
with aQIODevice
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
isFormatSupported()
. In case there are any snags, use theerror()
function to check what went wrong. We stop recording in thestopRecording()
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 theState
enum. You can request a state change directly throughsuspend()
,resume()
,stop()
,reset()
, andstart()
. The current state is reported bystate()
.QAudioOutput
will also signal you when the state changes (stateChanged()
).
QAudioInput
provides several ways of measuring the time that has passed since thestart()
of the recording. TheprocessedUSecs()
function returns the length of the stream in microseconds written, i.e., it leaves out the times the audio input was suspended or idle. TheelapsedUSecs()
function returns the time elapsed sincestart()
was called regardless of which states theQAudioInput
has been in.If an error should occur, you can fetch its reason with
error()
. The possible error reasons are described by theError
enum. TheQAudioInput
will enter theStoppedState
when an error is encountered. Connect to thestateChanged()
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; } }See also
- class PySide2.QtMultimedia.QAudioInput(audioDeviceInfo[, format=QAudioFormat()[, parent=None]])¶
PySide2.QtMultimedia.QAudioInput([format=QAudioFormat()[, parent=None]])
- param parent:
- param audioDeviceInfo:
- param format:
Construct a new audio input and attach it to
parent
. The device referenced byaudioDevice
is used with the inputformat
parameters.Construct a new audio input and attach it to
parent
. The default audio input device is used with the outputformat
parameters.
- PySide2.QtMultimedia.QAudioInput.bufferSize()¶
- Return type:
int
Returns the audio buffer size in bytes.
If called before
start()
, returns platform default value. If called beforestart()
butsetBufferSize()
was called prior, returns value set bysetBufferSize()
. If called afterstart()
, returns the actual buffer size being used. This may not be what was set previously bysetBufferSize()
.See also
- PySide2.QtMultimedia.QAudioInput.bytesReady()¶
- Return type:
int
Returns the amount of audio data available to read in bytes.
Note: returned value is only valid while in
ActiveState
orIdleState
state, otherwise returns zero.
- PySide2.QtMultimedia.QAudioInput.elapsedUSecs()¶
- Return type:
int
Returns the microseconds since
start()
was called, including time in Idle and Suspend states.
- PySide2.QtMultimedia.QAudioInput.format()¶
- Return type:
Returns the
QAudioFormat
being used.
- PySide2.QtMultimedia.QAudioInput.notify()¶
- PySide2.QtMultimedia.QAudioInput.notifyInterval()¶
- Return type:
int
Returns the notify interval in milliseconds.
See also
- PySide2.QtMultimedia.QAudioInput.periodSize()¶
- Return type:
int
Returns the period size in bytes.
Note: This is the recommended read size in bytes.
- PySide2.QtMultimedia.QAudioInput.processedUSecs()¶
- Return type:
int
Returns the amount of audio data processed since
start()
was called in microseconds.
- PySide2.QtMultimedia.QAudioInput.reset()¶
Drops all audio data in the buffers, resets buffers to zero.
- PySide2.QtMultimedia.QAudioInput.resume()¶
Resumes processing audio data after a
suspend()
.Sets
error()
toNoError
. Setsstate()
toActiveState
if you previously called start(QIODevice
*). Setsstate()
toIdleState
if you previously calledstart()
. emitsstateChanged()
signal.
- PySide2.QtMultimedia.QAudioInput.setBufferSize(bytes)¶
- Parameters:
bytes – int
Sets the audio buffer size to
value
bytes.Note: This function can be called anytime before
start()
, calls to this are ignored afterstart()
. It should not be assumed that the buffer size set is the actual buffer size used, callingbufferSize()
anytime afterstart()
will return the actual buffer size being used.See also
- PySide2.QtMultimedia.QAudioInput.setNotifyInterval(milliSeconds)¶
- Parameters:
milliSeconds – int
Sets the interval for
notify()
signal to be emitted. This is based on thems
of audio data processed not on actual real-time. The minimum resolution of the timer is platform specific and values should be checked withnotifyInterval()
to confirm actual value being used.See also
- PySide2.QtMultimedia.QAudioInput.setVolume(volume)¶
- Parameters:
volume – float
Sets the input volume to
volume
.The volume is scaled linearly from
0.0
(silence) to1.0
(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.The default volume is
1.0
.Note: Adjustments to the volume will change the volume of this audio stream, not the global volume.
See also
- PySide2.QtMultimedia.QAudioInput.start(device)¶
- Parameters:
device –
PySide2.QtCore.QIODevice
Starts transferring audio data from the system’s audio input to the
device
. Thedevice
must have been opened in theWriteOnly
,Append
orReadWrite
modes.If the
QAudioInput
is able to successfully get audio data,state()
returns eitherActiveState
orIdleState
,error()
returnsNoError
and thestateChanged()
signal is emitted.If a problem occurs during this process,
error()
returnsOpenError
,state()
returnsStoppedState
and thestateChanged()
signal is emitted.See also
QIODevice
- PySide2.QtMultimedia.QAudioInput.start()
- Return type:
Returns a pointer to the internal
QIODevice
being used to transfer data from the system’s audio input. The device will already be open andread()
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
QAudioInput
is able to access the system’s audio device,state()
returnsIdleState
,error()
returnsNoError
and thestateChanged()
signal is emitted.If a problem occurs during this process,
error()
returnsOpenError
,state()
returnsStoppedState
and thestateChanged()
signal is emitted.See also
QIODevice
- PySide2.QtMultimedia.QAudioInput.stop()¶
Stops the audio input, detaching from the system resource.
Sets
error()
toNoError
,state()
toStoppedState
and emitstateChanged()
signal.
- PySide2.QtMultimedia.QAudioInput.suspend()¶
Stops processing audio data, preserving buffered audio data.
Sets
error()
toNoError
,state()
toSuspendedState
and emitstateChanged()
signal.
- PySide2.QtMultimedia.QAudioInput.volume()¶
- Return type:
float
Returns the input volume.
If the device does not support adjusting the input volume the returned value will be 1.0.
See also
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