Synopsis#

Static functions#

def convertVolume()

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

Detailed Description#

class Error#

Constant	Description
QtAudio.NoError	No errors have occurred
QtAudio.OpenError	An error occurred opening the audio device
QtAudio.IOError	An error occurred during read/write of audio device
QtAudio.UnderrunError	Audio data is not being fed to the audio device at a fast enough rate
QtAudio.FatalError	A non-recoverable error has occurred, the audio device is not usable at this time.

class State#

Constant	Description
QtAudio.ActiveState	Audio data is being processed, this state is set after start() is called and while audio data is available to be processed.
QtAudio.SuspendedState	The audio stream is in a suspended state. Entered after suspend() is called or when another stream takes control of the audio device. In the later case, a call to resume will return control of the audio device to this stream. This should usually only be done upon user request.
QtAudio.StoppedState	The audio device is closed, and is not processing any audio data
QtAudio.IdleState	The QIODevice passed in has no data and audio system’s buffer is empty, this state is set after start() is called and while no audio data is available to be processed.

class VolumeScale#

This enum defines the different audio volume scales.

Constant

Description

QtAudio.LinearVolumeScale

Linear scale. 0.0 (0%) is silence and 1.0 (100%) is full volume. All Qt Multimedia classes that have an audio volume use a linear scale.

QtAudio.CubicVolumeScale

Cubic scale. 0.0 (0%) is silence and 1.0 (100%) is full volume.

QtAudio.LogarithmicVolumeScale

Logarithmic Scale. 0.0 (0%) is silence and 1.0 (100%) is full volume. UI volume controls should usually use a logarithmic scale.

QtAudio.DecibelVolumeScale

Decibel (dB, amplitude) logarithmic scale. -200 is silence and 0 is full volume.

See also

convertVolume()

Constant	Description
QtAudio.LinearVolumeScale	Linear scale. `0.0` (0%) is silence and `1.0` (100%) is full volume. All Qt Multimedia classes that have an audio volume use a linear scale.
QtAudio.CubicVolumeScale	Cubic scale. `0.0` (0%) is silence and `1.0` (100%) is full volume.
QtAudio.LogarithmicVolumeScale	Logarithmic Scale. `0.0` (0%) is silence and `1.0` (100%) is full volume. UI volume controls should usually use a logarithmic scale.
QtAudio.DecibelVolumeScale	Decibel (dB, amplitude) logarithmic scale. `-200` is silence and `0` is full volume.

static convertVolume(volume, from, to)#

Parameters:

volume – float
from – VolumeScale
to – VolumeScale

Return type:

float

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Converts an audio volume from a volume scale to another, and returns the result.

Depending on the context, different scales are used to represent audio volume. All Qt Multimedia classes that have an audio volume use a linear scale, the reason is that the loudness of a speaker is controlled by modulating its voltage on a linear scale. The human ear on the other hand, perceives loudness in a logarithmic way. Using a logarithmic scale for volume controls is therefore appropriate in most applications. The decibel scale is logarithmic by nature and is commonly used to define sound levels, it is usually used for UI volume controls in professional audio applications. The cubic scale is a computationally cheap approximation of a logarithmic scale, it provides more control over lower volume levels.

The following example shows how to convert the volume value from a slider control before passing it to a QMediaPlayer . As a result, the perceived increase in volume is the same when increasing the volume slider from 20 to 30 as it is from 50 to 60:

def applyVolume(volumeSliderValue):

    # volumeSliderValue is in the range [0..100]
    linearVolume = QtAudio.convertVolume(volumeSliderValue / qreal(100.0),()
                                                QtAudio.LogarithmicVolumeScale,
                                                QtAudio.LinearVolumeScale)
    player.setVolume(qRound(linearVolume * 100))