class QAudioDecoder

The QAudioDecoder class implements decoding audio. More…

Synopsis

Properties

• bufferAvailableᅟ - Whether there is a decoded audio buffer available

• errorᅟ

• isDecodingᅟ - True if the decoder is currently running and decoding audio data

• sourceᅟ - The active filename being decoded by the decoder object

Methods

• def __init__()

• def audioFormat()

• def bufferAvailable()

• def duration()

• def error()

• def errorString()

• def isDecoding()

• def isSupported()

• def position()

• def read()

• def setAudioFormat()

• def setSource()

• def setSourceDevice()

• def source()

• def sourceDevice()

Slots

• def start()

• def stop()

Signals

• def bufferAvailableChanged()

• def bufferReady()

• def durationChanged()

• def error()

• def finished()

• def formatChanged()

• def isDecodingChanged()

• def positionChanged()

• def sourceChanged()

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

The QAudioDecoder class is a high level class for decoding audio media files. It is similar to the QMediaPlayer class except that audio is provided back through this API rather than routed directly to audio hardware.

See also

QAudioBuffer

class Error

Defines a media player error condition.

Constant	Description
QAudioDecoder.NoError	No error has occurred.
QAudioDecoder.ResourceError	A media resource couldn’t be resolved.
QAudioDecoder.FormatError	The format of a media resource isn’t supported.
QAudioDecoder.AccessDeniedError	There are not the appropriate permissions to play a media resource.
QAudioDecoder.NotSupportedError	QAudioDecoder is not supported on this platform

Note

Properties can be used directly when from __feature__ import true_property is used or via accessor functions otherwise.

property bufferAvailableᅟ: bool

This property holds whether there is a decoded audio buffer available.

Access functions:

• bufferAvailable()

• Signal bufferAvailableChanged()

property errorᅟ: str

Returns a human readable description of the current error, or an empty string is there is no error.

Access functions:

• errorString()

property isDecodingᅟ: bool

This property holds true if the decoder is currently running and decoding audio data..

Access functions:

• isDecoding()

• Signal isDecodingChanged()

property sourceᅟ: QUrl

This property holds the active filename being decoded by the decoder object..

Access functions:

• source()

• setSource()

• Signal sourceChanged()

__init__([parent=None])

Parameters:

parent – QObject

Construct an QAudioDecoder instance with parent.

audioFormat()

Return type:

QAudioFormat

Returns the audio format the decoder is set to.

Note

This may be different than the format of the decoded samples, if the audio format was set to an invalid one.

See also

setAudioFormat() formatChanged()

bufferAvailable()

Return type:

bool

Returns true if a buffer is available to be read, and false otherwise. If there is no buffer available, calling the read() function will return an invalid buffer.

Getter of property bufferAvailableᅟ .

bufferAvailableChanged(arg__1)

Parameters:

arg__1 – bool

Signals the availability (if available is true) of a new buffer.

If available is false, there are no buffers available.

See also

bufferAvailable() bufferReady()

Notification signal of property bufferAvailableᅟ .

bufferReady()

Signals that a new decoded audio buffer is available to be read.

See also

read() bufferAvailable()

duration()

Return type:

int

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

durationChanged(duration)

Parameters:

duration – int

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

See also

positionChanged()

error()

Return type:

Error

Returns the current error state of the QAudioDecoder .

error(error)

Parameters:

error – Error

Signals that an error condition has occurred.

See also

errorString()

errorString()

Return type:

str

Getter of property errorᅟ .

finished()

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

See also

start() stop() error()

formatChanged(format)

Parameters:

format – QAudioFormat

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

See also

audioFormat() setAudioFormat()

isDecoding()

Return type:

bool

Getter of property isDecodingᅟ .

isDecodingChanged(arg__1)

Parameters:

arg__1 – bool

Notification signal of property isDecodingᅟ .

isSupported()

Return type:

bool

Returns true is audio decoding is supported on this platform.

position()

Return type:

int

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

positionChanged(position)

Parameters:

position – int

Signals that the current position of the decoder has changed.

See also

durationChanged()

read()

Return type:

QAudioBuffer

Read a buffer from the decoder, if one is available. Returns an invalid buffer if there are no decoded buffers currently available, or on failure. In both cases this function will not block.

You should either respond to the bufferReady() signal or check the bufferAvailable() function before calling read() to make sure you get useful data.

setAudioFormat(format)

Parameters:

format – QAudioFormat

Set the desired audio format for decoded samples to format.

This property can only be set while the decoder is stopped. Setting this property at other times will be ignored.

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.

Warning

Setting a desired audio format is not yet supported on the Android backend. It does work with the default FFMPEG backend.

See also

audioFormat()

setSource(fileName)

Parameters:

fileName – QUrl

Sets the current audio file name to fileName.

When this property is set any current decoding is stopped, and any audio buffers are discarded.

You can only specify either a source filename or a source QIODevice. Setting one will unset the other.

See also

source()

Setter of property sourceᅟ .

setSourceDevice(device)

Parameters:

device – QIODevice

Sets the current audio QIODevice to device.

When this property is set any current decoding is stopped, and any audio buffers are discarded.

You can only specify either a source filename or a source QIODevice. Setting one will unset the other.

See also

sourceDevice()

source()

Return type:

QUrl

Returns the current file name to decode. If setSourceDevice was called, this will be empty.

See also

setSource()

Getter of property sourceᅟ .

sourceChanged()

Signals that the current source of the decoder has changed.

See also

source() sourceDevice()

Notification signal of property sourceᅟ .

sourceDevice()

Return type:

QIODevice

Returns the current source QIODevice, if one was set. If setSource() was called, this will be a nullptr.

See also

setSourceDevice()

start()

Starts decoding the audio resource.

As data gets decoded, the bufferReady() signal will be emitted when enough data has been decoded. Calling read() will then return an audio buffer without blocking.

If you call read() before a buffer is ready, an invalid buffer will be returned, again without blocking.

See also

read()

stop()

Stop decoding audio. Calling start() again will resume decoding from the beginning.