内容

公共类型
特性
公共函数
公共槽
信号
静态公共成员
详细描述

QAudioDecoder 类

QAudioDecoder 类允许解码音频。更多...

头：	#include <QAudioDecoder>
qmake:	QT += multimedia
继承：	QMediaObject

该类在开发且可能改变。

所有成员列表，包括继承成员

公共类型

enum	Error { NoError, ResourceError, FormatError, AccessDeniedError, ServiceMissingError }
enum	State { StoppedState, DecodingState }

特性

bufferAvailable : const bool
error : const QString
sourceFilename : QString
state : const State

公共函数

	QAudioDecoder (QObject * parent = nullptr)
virtual	~QAudioDecoder ()
QAudioFormat	audioFormat () const
bool	bufferAvailable () const
qint64	duration () const
QAudioDecoder::Error	error () const
QString	errorString () const
qint64	position () const
QAudioBuffer	read () const
void	setAudioFormat (const QAudioFormat & format )
void	setSourceDevice (QIODevice * device )
void	setSourceFilename (const QString & fileName )
QIODevice *	sourceDevice () const
QString	sourceFilename () const
QAudioDecoder::State	state () const

公共槽

void	start ()
void	stop ()

信号

void	bufferAvailableChanged (bool available )
void	bufferReady ()
void	durationChanged (qint64 duration )
void	error (QAudioDecoder::Error error )
void	finished ()
void	formatChanged (const QAudioFormat & format )
void	positionChanged (qint64 position )
void	sourceChanged ()
void	stateChanged (QAudioDecoder::State state )

静态公共成员

QMultimedia::SupportEstimate hasSupport (const QString & mimeType , const QStringList & codecs = QStringList())

详细描述

The QAudioDecoder class is a high level class for decoding local 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, and playlists and network and streaming based media is not supported.

另请参阅 QAudioBuffer .

成员类型文档编制

enum QAudioDecoder:: Error

定义媒体播放器错误条件。

常量	值	描述
`QAudioDecoder::NoError`	`0`	没有出现错误。
`QAudioDecoder::ResourceError`	`1`	无法解析媒体资源。
`QAudioDecoder::FormatError`	`2`	媒体资源格式不支持。
`QAudioDecoder::AccessDeniedError`	`3`	没有适当权限来播放媒体资源。
`QAudioDecoder::ServiceMissingError`	`4`	找不到有效回放服务，无法继续进行播放。开头

enum QAudioDecoder:: State

定义媒体播放器的当前状态。

常量	值	描述
`QAudioDecoder::StoppedState`	`0`	The decoder is not decoding. Decoding will start at the start of the media.
`QAudioDecoder::DecodingState`	`1`	The audio player is currently decoding media.

特性文档编制

bufferAvailable : const bool

This property holds whether there is a decoded audio buffer available

访问函数：

bool	bufferAvailable () const

通知程序信号：

void	bufferAvailableChanged (bool available )

error : const QString

This property holds a string describing the last error condition.

访问函数：

QString errorString () const

另请参阅 error ().

sourceFilename : QString

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

访问函数：

QString	sourceFilename () const
void	setSourceFilename (const QString & fileName )

通知程序信号：

void	sourceChanged ()

state : const State

This property holds the audio decoder's playback state.

By default this property is QAudioDecoder::Stopped

访问函数：

QAudioDecoder::State state () const

通知程序信号：

void	stateChanged (QAudioDecoder::State state )

另请参阅 start () 和 stop ().

成员函数文档编制

QAudioDecoder:: QAudioDecoder ( QObject * parent = nullptr)

Construct an QAudioDecoder instance parented to parent .

`[signal]` void QAudioDecoder:: bufferAvailableChanged ( bool available )

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

若 available is false, there are no buffers available.

注意： 通知程序信号对于特性 bufferAvailable .

另请参阅 bufferAvailable () 和 bufferReady ().

`[signal]` void QAudioDecoder:: bufferReady ()

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

另请参阅 read () 和 bufferAvailable ().

`[signal]` void QAudioDecoder:: durationChanged ( qint64 duration )

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

另请参阅 positionChanged ().

`[signal]` void QAudioDecoder:: error ( QAudioDecoder::Error error )

Signals that an error 条件已发生。

注意： 信号 error 在此类中被重载。通过使用函数指针句法连接到此信号，Qt 提供用于获得如此范例展示的函数指针的方便帮助程序：

connect(audioDecoder, QOverload<QAudioDecoder::Error>::of(&QAudioDecoder::error),
    [=](QAudioDecoder::Error error){ /* ... */ });

另请参阅 errorString ().

`[signal]` void QAudioDecoder:: finished ()

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

另请参阅 start (), stop ()，和 error ().

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

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

另请参阅 audioFormat () 和 setAudioFormat ().

`[signal]` void QAudioDecoder:: positionChanged ( qint64 position )

Signals that the current position of the decoder has changed.

另请参阅 durationChanged ().

`[signal]` void QAudioDecoder:: sourceChanged ()

Signals that the current source of the decoder has changed.

注意： 通知程序信号对于特性 sourceFilename .

另请参阅 sourceFilename () 和 sourceDevice ().

`[slot]` void QAudioDecoder:: start ()

开始解码音频资源。

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.

若调用 read () before a buffer is ready, an invalid buffer will be returned, again without blocking.

另请参阅 read ().

`[signal]` void QAudioDecoder:: stateChanged ( QAudioDecoder::State state )

信号 state of the decoder object has changed.

注意： 通知程序信号对于特性 state .

`[slot]` void QAudioDecoder:: stop ()

停止解码音频。调用 start () again will resume decoding from the beginning.

`[virtual]` QAudioDecoder:: ~QAudioDecoder ()

销毁音频解码器对象。

QAudioFormat QAudioDecoder:: audioFormat () const

Returns the current audio format of the decoded stream.

Any buffers returned should have this format.

另请参阅 setAudioFormat () 和 formatChanged ().

bool QAudioDecoder:: bufferAvailable () const

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.

注意： Getter 函数对于特性 bufferAvailable。

qint64 QAudioDecoder:: duration () const

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

QAudioDecoder::Error QAudioDecoder:: error () const

返回当前错误状态。

`[static]` QMultimedia::SupportEstimate QAudioDecoder:: hasSupport (const QString & mimeType , const QStringList & codecs = QStringList())

Returns the level of support an audio decoder has for a mimeType and a set of codecs .

qint64 QAudioDecoder:: position () const

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

QAudioBuffer QAudioDecoder:: read () const

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.

void QAudioDecoder:: setAudioFormat (const QAudioFormat & format )

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 .

另请参阅 audioFormat ().

void QAudioDecoder:: setSourceDevice ( QIODevice * device )

设置当前音频 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.

另请参阅 sourceDevice ().

void QAudioDecoder:: setSourceFilename (const QString & fileName )

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.

注意： Setter 函数对于特性 sourceFilename .

另请参阅 sourceFilename ().

QIODevice *QAudioDecoder:: sourceDevice () const

返回当前源 QIODevice , if one was set. If setSourceFilename () was called, this will be 0.

另请参阅 setSourceDevice ().

QString QAudioDecoder:: sourceFilename () const

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

注意： Getter function for property sourceFilename.

另请参阅 setSourceFilename ().

内容

QAudioDecoder 类

公共类型

特性

公共函数

公共槽

信号

静态公共成员

详细描述

成员类型文档编制

enum QAudioDecoder:: Error

enum QAudioDecoder:: State

特性文档编制

bufferAvailable : const bool

error : const QString

sourceFilename : QString

state : const State

成员函数文档编制

QAudioDecoder:: QAudioDecoder ( QObject * parent = nullptr)

[signal] void QAudioDecoder:: bufferAvailableChanged ( bool available )

[signal] void QAudioDecoder:: bufferReady ()

[signal] void QAudioDecoder:: durationChanged ( qint64 duration )

[signal] void QAudioDecoder:: error ( QAudioDecoder::Error error )

[signal] void QAudioDecoder:: finished ()

[signal] void QAudioDecoder:: formatChanged (const QAudioFormat & format )

[signal] void QAudioDecoder:: positionChanged ( qint64 position )

[signal] void QAudioDecoder:: sourceChanged ()

[slot] void QAudioDecoder:: start ()

[signal] void QAudioDecoder:: stateChanged ( QAudioDecoder::State state )

[slot] void QAudioDecoder:: stop ()

[virtual] QAudioDecoder:: ~QAudioDecoder ()

QAudioFormat QAudioDecoder:: audioFormat () const

bool QAudioDecoder:: bufferAvailable () const

qint64 QAudioDecoder:: duration () const

QAudioDecoder::Error QAudioDecoder:: error () const

[static] QMultimedia::SupportEstimate QAudioDecoder:: hasSupport (const QString & mimeType , const QStringList & codecs = QStringList())

qint64 QAudioDecoder:: position () const

QAudioBuffer QAudioDecoder:: read () const

void QAudioDecoder:: setAudioFormat (const QAudioFormat & format )

void QAudioDecoder:: setSourceDevice ( QIODevice * device )

void QAudioDecoder:: setSourceFilename (const QString & fileName )

QIODevice *QAudioDecoder:: sourceDevice () const

QString QAudioDecoder:: sourceFilename () const

`[signal]` void QAudioDecoder:: bufferAvailableChanged ( bool available )

`[signal]` void QAudioDecoder:: bufferReady ()

`[signal]` void QAudioDecoder:: durationChanged ( qint64 duration )

`[signal]` void QAudioDecoder:: error ( QAudioDecoder::Error error )

`[signal]` void QAudioDecoder:: finished ()

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

`[signal]` void QAudioDecoder:: positionChanged ( qint64 position )

`[signal]` void QAudioDecoder:: sourceChanged ()

`[slot]` void QAudioDecoder:: start ()

`[signal]` void QAudioDecoder:: stateChanged ( QAudioDecoder::State state )

`[slot]` void QAudioDecoder:: stop ()

`[virtual]` QAudioDecoder:: ~QAudioDecoder ()

`[static]` QMultimedia::SupportEstimate QAudioDecoder:: hasSupport (const QString & mimeType , const QStringList & codecs = QStringList())