The QAudioDecoder class allows decoding audio. 更多...
| 头： | #include <QAudioDecoder> |
| qmake: | QT += multimedia |
| 继承： | QMediaObject |
该类在开发且可能改变。
| enum | Error { NoError, ResourceError, FormatError, AccessDeniedError, ServiceMissingError } |
| enum | State { StoppedState, DecodingState } |
| 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 |
| void | start () |
| void | stop () |
| 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 ) |
| QMultimedia::SupportEstimate | hasSupport (const QString & mimeType , const QStringList & codecs = QStringList()) |
| const QMetaObject | staticMetaObject |
The QAudioDecoder class allows decoding audio.
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 .
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 |
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. |
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 ) |
此特性保持描述最后一个错误条件的字符串。
访问函数：
| QString | errorString () const |
另请参阅 error ().
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 () |
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 ) |
Construct an QAudioDecoder instance parented to parent .
[虚拟]
QAudioDecoder::
~QAudioDecoder
()
销毁音频解码器对象。
Returns the current audio format of the decoded stream.
Any buffers returned should have this format.
另请参阅 setAudioFormat () 和 formatChanged ().
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 .
[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 ().
Returns total duration (in milliseconds) of the audio stream or -1 if not available.
[signal]
void
QAudioDecoder::
durationChanged
(
qint64
duration
)
Signals that the estimated duration of the decoded data has changed.
另请参阅 positionChanged ().
返回当前错误状态。
[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 ().
[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 .
Returns position (in milliseconds) of the last buffer read from the decoder or -1 if no buffers have been read.
[signal]
void
QAudioDecoder::
positionChanged
(
qint64
position
)
Signals that the current position of the decoder has changed.
另请参阅 durationChanged ().
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.
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
() 会被设为
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 ().
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 ().
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 ().
[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 ().
返回当前源 QIODevice , if one was set. If setSourceFilename () was called, this will be 0.
另请参阅 setSourceDevice ().
Returns the current file name to decode. If setSourceDevice was called, this will be empty.
注意： getter 函数对于特性 sourceFilename .
另请参阅 setSourceFilename ().
[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.