QAudioBuffer Class

The QAudioBuffer class represents a collection of audio samples with a specific format and sample rate. More...

Header: #include <QAudioBuffer>
CMake: find_package(Qt6 COMPONENTS Multimedia REQUIRED)
target_link_libraries(mytarget PRIVATE Qt6::Multimedia)
qmake: QT += multimedia

Public Types

Public Functions

QAudioBuffer(QAudioBuffer &&other)
QAudioBuffer(int numFrames, const QAudioFormat &format, qint64 startTime = -1)
QAudioBuffer(const QByteArray &data, const QAudioFormat &format, qint64 startTime = -1)
QAudioBuffer(const QAudioBuffer &other)
QAudioBuffer()
QAudioBuffer &operator=(QAudioBuffer &&other)
QAudioBuffer &operator=(const QAudioBuffer &other)
~QAudioBuffer()
qsizetype byteCount() const
const T *constData() const
const T *data() const
T *data()
void detach()
qint64 duration() const
QAudioFormat format() const
qsizetype frameCount() const
bool isValid() const
qsizetype sampleCount() const
qint64 startTime() const

Detailed Description

QAudioBuffer is used by the QAudioDecoder class to hand decoded audio data over to the application. An audio buffer contains data in a certain QAudioFormat that can be queried using format(). It is also tagged with timing and duration information.

To access the data stored inside the buffer, use the data() or constData() methods.

Audio buffers are explicitly shared, in most cases, you should call detach() before modifying the data.

Member Type Documentation

QAudioBuffer::S16S

This is a predefined specialization for a signed stereo 16 bit sample. Each channel is a signed short.

Member Function Documentation

QAudioBuffer::QAudioBuffer(QAudioBuffer &&other)

Constructs a QAudioBuffer by moving from other.

QAudioBuffer::QAudioBuffer(int numFrames, const QAudioFormat &format, qint64 startTime = -1)

Creates a new audio buffer with space for numFrames frames of the given format. The individual samples will be initialized to the default for the format.

startTime (in microseconds) indicates when this buffer starts in the stream. If this buffer is not part of a stream, set it to -1.

QAudioBuffer::QAudioBuffer(const QByteArray &data, const QAudioFormat &format, qint64 startTime = -1)

Creates a new audio buffer from the supplied data, in the given format. The format will determine how the number and sizes of the samples are interpreted from the data.

If the supplied data is not an integer multiple of the calculated frame size, the excess data will not be used.

This audio buffer will copy the contents of data.

startTime (in microseconds) indicates when this buffer starts in the stream. If this buffer is not part of a stream, set it to -1.

QAudioBuffer::QAudioBuffer(const QAudioBuffer &other)

Creates a new audio buffer from other. Audio buffers are explicitly shared, you should call detach() on the buffer to make a copy that can then be modified.

QAudioBuffer::QAudioBuffer()

Create a new, empty, invalid buffer.

QAudioBuffer &QAudioBuffer::operator=(QAudioBuffer &&other)

Moves other into this QAudioBuffer.

QAudioBuffer &QAudioBuffer::operator=(const QAudioBuffer &other)

Assigns the other buffer to this.

QAudioBuffer::~QAudioBuffer()

Destroys this audio buffer.

qsizetype QAudioBuffer::byteCount() const

Returns the size of this buffer, in bytes.

template <typename T> const T *QAudioBuffer::constData() const

Returns a pointer to this buffer's data. You can only read it.

This method is preferred over the const version of data() to prevent unnecessary copying.

There is also a templatized version of this constData() function that allows you to retrieve a specific type of read-only pointer to the data. Note that there is no checking done on the format of the audio buffer - this is simply a convenience function.

// With a 16bit sample buffer:
const quint16 *data = buffer->constData<quint16>();

template <typename T> const T *QAudioBuffer::data() const

Returns a pointer to this buffer's data. You can only read it.

You should use the constData() function rather than this to prevent accidental deep copying.

There is also a templatized version of this data() function that allows you to retrieve a specific type of read-only pointer to the data. Note that there is no checking done on the format of the audio buffer - this is simply a convenience function.

// With a 16bit sample const buffer:
const quint16 *data = buffer->data<quint16>();

template <typename T> T *QAudioBuffer::data()

Returns a pointer to this buffer's data. You can modify the data through the returned pointer.

Since QAudioBuffer objects are explicitly shared, you should usually call detach() before modifying the data through this function.

There is also a templatized version of data() allows you to retrieve a specific type of pointer to the data. Note that there is no checking done on the format of the audio buffer - this is simply a convenience function.

// With a 16bit sample buffer:
quint16 *data = buffer->data<quint16>(); // May cause deep copy

void QAudioBuffer::detach()

Detaches this audio buffers from other copies that might share data with it.

qint64 QAudioBuffer::duration() const

Returns the duration of audio in this buffer, in microseconds.

This depends on the format(), and the frameCount().

QAudioFormat QAudioBuffer::format() const

Returns the format of this buffer.

Several properties of this format influence how the duration() or byteCount() are calculated from the frameCount().

qsizetype QAudioBuffer::frameCount() const

Returns the number of complete audio frames in this buffer.

An audio frame is an interleaved set of one sample per channel for the same instant in time.

bool QAudioBuffer::isValid() const

Returns true if this is a valid buffer. A valid buffer has more than zero frames in it and a valid format.

qsizetype QAudioBuffer::sampleCount() const

Returns the number of samples in this buffer.

If the format of this buffer has multiple channels, then this count includes all channels. This means that a stereo buffer with 1000 samples in total will have 500 left samples and 500 right samples (interleaved), and this function will return 1000.

See also frameCount().

qint64 QAudioBuffer::startTime() const

Returns the time in a stream that this buffer starts at (in microseconds).

If this buffer is not part of a stream, this will return -1.

© 2021 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners.