- Qt 5.15
- Qt Multimedia
- C++ Classes
- QAudioDecoderControl
- Qt 5.15.19 Reference Documentation

# QAudioDecoderControl Class

The QAudioDecoderControl class provides access to the audio decoding functionality of a QMediaService. More...

Header: | #include <QAudioDecoderControl>
qmake: | QT += multimedia
Inherits: | QMediaControl

This class is under development and is subject to change.

- List of all members, including inherited members

## Public Functions

virtual | ~QAudioDecoderControl()
virtual QAudioFormat | audioFormat() const = 0
virtual bool | bufferAvailable() const = 0
virtual qint64 | duration() const = 0
virtual qint64 | position() const = 0
virtual QAudioBuffer | read() = 0
virtual void | setAudioFormat(const QAudioFormat &format) = 0
virtual void | setSourceDevice(QIODevice *device) = 0
virtual void | setSourceFilename(const QString &fileName) = 0
virtual QIODevice * | sourceDevice() const = 0
virtual QString | sourceFilename() const = 0
virtual void | start() = 0
virtual QAudioDecoder::State | state() const = 0
virtual void | stop() = 0

## Signals

void | bufferAvailableChanged(bool available)
void | bufferReady()
void | durationChanged(qint64 duration)
void | error(int error, const QString &errorString)
void | finished()
void | formatChanged(const QAudioFormat &format)
void | positionChanged(qint64 position)
void | sourceChanged()
void | stateChanged(QAudioDecoder::State newState)

## Protected Functions

| QAudioDecoderControl(QObject *parent = nullptr)

## Macros

| QAudioDecoderControl_iid

## Detailed Description

The functionality provided by this control is exposed to application code through the QAudioDecoder class.

The interface name of QAudioDecoderControl is `org.qt-project.qt.audiodecodercontrol/5.0` as defined in QAudioDecoderControl_iid.

See also QMediaService::requestControl() and QAudioDecoder.

## Member Function Documentation

### `[protected]` QAudioDecoderControl::QAudioDecoderControl(QObject *parent = nullptr)

Constructs a new audio decoder control with the given parent.

### `[signal]` void QAudioDecoderControl::bufferAvailableChanged(bool available)

Signals that the bufferAvailable property has changed to available.

### `[signal]` void QAudioDecoderControl::bufferReady()

Signals that a new buffer is ready for reading.

### `[signal]` void QAudioDecoderControl::durationChanged(qint64 duration)

Signals that the estimated duration of the decoded data has changed.

See also positionChanged().

### `[signal]` void QAudioDecoderControl::error(int error, const QString &errorString)

Signals that an error has occurred. The errorString provides a more detailed explanation.

### `[signal]` void QAudioDecoderControl::finished()

Signals that the decoding has finished successfully. If decoding fails, error signal is emitted instead.

See also start(), stop(), and error().

### `[signal]` void QAudioDecoderControl::formatChanged(const QAudioFormat &format)

Signals that the current audio format of the decoder has changed to format.

See also audioFormat() and setAudioFormat().

### `[signal]` void QAudioDecoderControl::positionChanged(qint64 position)

Signals that the current position of the decoder has changed.

See also durationChanged().

### `[signal]` void QAudioDecoderControl::sourceChanged()

Signals that the current source of the decoder has changed.

See also sourceFilename() and sourceDevice().

### `[signal]` void QAudioDecoderControl::stateChanged(QAudioDecoder::State newState)

Signals that the state of a player control has changed to newState.

See also state().

### `[virtual]` QAudioDecoderControl::~QAudioDecoderControl()

Destroys an audio decoder control.

### `[pure virtual]` QAudioFormat QAudioDecoderControl::audioFormat() const

Returns the current audio format of the decoded stream.

Any buffers returned should have this format.

See also setAudioFormat() and formatChanged().

### `[pure virtual]` bool QAudioDecoderControl::bufferAvailable() const

Returns true if a buffer is available to be read, and false otherwise.

### `[pure virtual]` qint64 QAudioDecoderControl::duration() const

Returns total duration (in milliseconds) of the audio stream or -1 if not available.

### `[pure virtual]` qint64 QAudioDecoderControl::position() const

Returns position (in milliseconds) of the last buffer read from the decoder or -1 if no buffers have been read.

### `[pure virtual]` QAudioBuffer QAudioDecoderControl::read()

Attempts to read a buffer from the decoder, without blocking. Returns invalid buffer if there are no decoded buffers available, or on error.

### `[pure virtual]` void QAudioDecoderControl::setAudioFormat(const QAudioFormat &format)

Set the desired audio format for decoded samples to format.

If the decoder does not support this format, error() will be set to `FormatError`.

If you do not specify a format, the format of the decoded audio itself will be used. Otherwise, some format conversion will be applied.

If you wish to reset the decoded format to that of the original audio file, you can specify an invalid format.

See also audioFormat().

### `[pure virtual]` void QAudioDecoderControl::setSourceDevice(QIODevice *device)

Sets the current source to device. Changing the source will stop any current decoding and discard any buffers.

Sources are exclusive, so only one can be set.

See also sourceDevice().

### `[pure virtual]` void QAudioDecoderControl::setSourceFilename(const QString &fileName)

Sets the current source to fileName. Changing the source will stop any current decoding and discard any buffers.

Sources are exclusive, so only one can be set.

See also sourceFilename().

### `[pure virtual]` QIODevice *QAudioDecoderControl::sourceDevice() const

Returns the current media source QIODevice, or 0 if none (or a file).

See also setSourceDevice().

### `[pure virtual]` QString QAudioDecoderControl::sourceFilename() const

Returns the current media source filename, or a null QString if none (or a device)

See also setSourceFilename().

### `[pure virtual]` void QAudioDecoderControl::start()

Starts decoding the current media.

If successful the player control will immediately enter the decoding state.

See also state() and read().

### `[pure virtual]` QAudioDecoder::State QAudioDecoderControl::state() const

Returns the state of a player control.

### `[pure virtual]` void QAudioDecoderControl::stop()

Stops playback of the current media and discards any buffers.

If successful the player control will immediately enter the stopped state.

## Macro Documentation

### QAudioDecoderControl_iid

`org.qt-project.qt.audiodecodercontrol/5.0`

Defines the interface name of the QAudioDecoderControl class.