Extractor

java.lang.Object
- ohos.media.extractor.Extractor

```
public class Extractor
extends Object
```
Separates audio from video data in multimedia files and extracts audio and video data sources.
This class is used together with other classes to implement different functions. Example scenarios:
1. Working with the Muxer class: The Extractor class separates multimedia audio and video sources, and the Muxer class combines the data sources into a new media file.
2. Working with the Codec class: The Extractor class separates multimedia audio and video data sources, and the Codec class decodes
the audio and video data in the data sources, and encodes the decoded data into the required output format.
Example code:
```
 Source source = new Source(...);
 Extractor extractor = new Extractor();
 extractor.setSource(source);
 int trackCount = extractor.getTotalStreams();
 for (int i = 0; i < trackCount, i++) {
     extractor.specifyStream(i);
     Format format = extractor.getStreamFormat();
 }
 ByteBuffer byteBuffer = ByteBuffer.allocate(size);
 while(extractor.readBuffer(byteBuffer, 0) > 0) {
     extractor.getFrameTimestamp();
     extractor.getFrameType();
     extractor.next();
 }
 extractor.release();
 
```
从以下版本开始:

1

SystemCapability

SystemCapability.Multimedia#MEDIA

字段概要

字段
限定符和类型	字段	说明
`static int`	`REWIND_TO_CLOSEST_SYNC`	Indicates the closest key frame of a specified frame.
`static int`	`REWIND_TO_NEXT_SYNC`	Indicates the next key frame of a specified frame.
`static int`	`REWIND_TO_PREVIOUS_SYNC`	Indicates the previous key frame of a specified frame.

构造器概要

构造器
构造器说明

Extractor()
Default constructor used to create an Extractor instance.

构造器
构造器	说明
`Extractor()`	Default constructor used to create an `Extractor` instance.

方法概要

所有方法实例方法具体方法
限定符和类型	方法	说明
`protected void`	`finalize()`	Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`long`	`getFrameSize()`	Obtains the size of a data source, in bytes.
`long`	`getFrameTimestamp()`	Obtains the time point of a data source, in milliseconds.
`int`	`getFrameType()`	Obtains the type of a data source.
`Format`	`getStreamFormat(int id)`	Obtains the data format of a stream.
`int`	`getStreamId()`	Obtains the ID of the track to which the data source belongs.
`int`	`getTotalStreams()`	Obtains the total number of tracks in a media file.
`boolean`	`next()`	Rewinds to the next frame.
`int`	`readBuffer(ByteBuffer buf, int offset)`	Reads demultiplexed data.
`boolean`	`release()`	Releases resources.
`boolean`	`rewindTo(long microseconds, int mode)`	Rewinds to a specified frame based on the time and mode.
`boolean`	`setSource(Source source)`	Sets the media playback source.
`boolean`	`specifyStream(int id)`	Selects a track in a media file.
`boolean`	`unspecifyStream(int id)`	Deselects a track.

从类继承的方法 java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- 字段详细资料
  - REWIND_TO_CLOSEST_SYNC
```
public static final int REWIND_TO_CLOSEST_SYNC
```
    Indicates the closest key frame of a specified frame.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
  - REWIND_TO_NEXT_SYNC
```
public static final int REWIND_TO_NEXT_SYNC
```
    Indicates the next key frame of a specified frame.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
  - REWIND_TO_PREVIOUS_SYNC
```
public static final int REWIND_TO_PREVIOUS_SYNC
```
    Indicates the previous key frame of a specified frame.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
- 构造器详细资料
  - Extractor
```
public Extractor()
```
    Default constructor used to create an Extractor instance.
    
    从以下版本开始:
    
    1
- 方法详细资料
  - setSource
```
public boolean setSource(Source source)
```
    Sets the media playback source.
    This method must be called prior to other methods of the Extractor class.
    
    参数:
    
    source - Indicates the source of the media to demultiplex.
    
    返回:
    
    Returns true if the setting is successful; returns false otherwise.
    
    抛出:
    
    IllegalArgumentException - Throws this exception if a parameter is invalid.
    
    从以下版本开始:
    
    1
  - getStreamFormat
```
public final Format getStreamFormat(int id)
```
    Obtains the data format of a stream. For details on the supported data formats, see Format.
    
    参数:
    
    id - Indicates a stream ID, which is a non-negative number.
    
    返回:
    
    Returns the data format.
    
    抛出:
    
    IllegalArgumentException - Throws this exception if a parameter is invalid.
    
    从以下版本开始:
    
    1
  - getTotalStreams
```
public final int getTotalStreams()
```
    Obtains the total number of tracks in a media file.
    
    返回:
    
    Returns the total number of tracks.
    
    从以下版本开始:
    
    1
  - specifyStream
```
public boolean specifyStream(int id)
```
    Selects a track in a media file.
    
    参数:
    
    id - Indicates a track ID, which is a non-negative number.
    
    返回:
    
    Returns true if the track is selected; returns false otherwise.
    
    抛出:
    
    IllegalArgumentException - Throws this exception if a parameter is invalid.
    
    从以下版本开始:
    
    1
  - unspecifyStream
```
public boolean unspecifyStream(int id)
```
    Deselects a track.
    To reselect a track that has been selected, you must first deselect it.
    
    参数:
    
    id - Indicates a track ID.
    
    返回:
    
    Returns true if the track is deselected; returns false otherwise.
    
    抛出:
    
    IllegalArgumentException - Throws this exception if a parameter is invalid.
    
    从以下版本开始:
    
    1
  - rewindTo
```
public boolean rewindTo(long microseconds,
                        int mode)
```
    Rewinds to a specified frame based on the time and mode.
    This method can be called before, during, and after a media file is played.
    参数:
    
    microseconds - Indicates the time point, in microseconds. It is a non-negative number.
    mode - Indicates the rewinding mode.
    
    REWIND_TO_PREVIOUS_SYNC - Rewinds to the previous frame.
    REWIND_TO_CLOSEST_SYNC - Rewinds to the closest frame, which can either be the previous or next one.
    REWIND_TO_NEXT_SYNC - Rewinds to the next frame.
    返回:
    
    Returns true if the rewinding operation is successful; returns false otherwise.
    
    从以下版本开始:
    
    1
  - next
```
public boolean next()
```
    Rewinds to the next frame.
    
    返回:
    
    Returns true if the rewinding operation is successful; returns false otherwise.
    
    从以下版本开始:
    
    1
  - readBuffer
```
public int readBuffer(ByteBuffer buf,
                      int offset)
```
    Reads demultiplexed data.
    Before calling this method, you must call specifyStream() to select a track.
    
    参数:
    
    buf - Indicates the buffer from which data is read.
    
    offset - Indicates the start position of the data in the buffer, which is a non-negative number.
    
    返回:
    
    Returns the size of the data if obtained; returns -1 if no data has been read.
    
    从以下版本开始:
    
    1
  - getStreamId
```
public int getStreamId()
```
    Obtains the ID of the track to which the data source belongs.
    
    返回:
    
    Returns the track ID.
    
    从以下版本开始:
    
    1
  - getFrameTimestamp
```
public long getFrameTimestamp()
```
    Obtains the time point of a data source, in milliseconds.
    
    返回:
    
    Returns the timestamp; returns -1 if no sample is available.
    
    从以下版本开始:
    
    1
  - getFrameSize
```
public long getFrameSize()
```
    Obtains the size of a data source, in bytes.
    
    返回:
    
    Returns the size of the data source if obtained; returns -1 if no data is available.
    
    从以下版本开始:
    
    1
  - getFrameType
```
public int getFrameType()
```
    Obtains the type of a data source.
    
    返回:
    
    Returns the flags if obtained; returns 0 if an exception occurs.
    type: SAMPLE_FLAG_SYNC - Indicates that a key frame is read from the buffer.
    SAMPLE_FLAG_ENCRYPTED - Indicates that an encrypted frame is read from the buffer.
    SAMPLE_FLAG_PARTIAL_FRAME - Indicates that an incomplete frame is read from the buffer.
    
    从以下版本开始:
    
    1
  - release
```
public boolean release()
```
    Releases resources.
    
    返回:
    
    Returns true if the resources are released; returns false otherwise.
    
    从以下版本开始:
    
    1
  - finalize
```
protected void finalize()
                 throws Throwable
```
    从类复制的说明: Object
    
    Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. A subclass overrides the finalize method to dispose of system resources or to perform other cleanup.
    The general contract of finalize is that it is invoked if and when the Java™ virtual machine has determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, except as a result of an action taken by the finalization of some other object or class which is ready to be finalized. The finalize method may take any action, including making this object available again to other threads; the usual purpose of finalize, however, is to perform cleanup actions before the object is irrevocably discarded. For example, the finalize method for an object that represents an input/output connection might perform explicit I/O transactions to break the connection before the object is permanently discarded.
    The finalize method of class Object performs no special action; it simply returns normally. Subclasses of Object may override this definition.
    The Java programming language does not guarantee which thread will invoke the finalize method for any given object. It is guaranteed, however, that the thread that invokes finalize will not be holding any user-visible synchronization locks when finalize is invoked. If an uncaught exception is thrown by the finalize method, the exception is ignored and finalization of that object terminates.
    After the finalize method has been invoked for an object, no further action is taken until the Java virtual machine has again determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, including possible actions by other objects or classes which are ready to be finalized, at which point the object may be discarded.
    The finalize method is never invoked more than once by a Java virtual machine for any given object.
    Any exception thrown by the finalize method causes the finalization of this object to be halted, but is otherwise ignored.
    
    覆盖:
    
    finalize 在类中 Object
    
    抛出:
    
    Throwable - the Exception raised by this method
    
    另请参阅:
    
    WeakReference, PhantomReference

类 Extractor

字段概要

构造器概要

方法概要

从类继承的方法 java.lang.Object

字段详细资料

REWIND_TO_CLOSEST_SYNC

REWIND_TO_NEXT_SYNC

REWIND_TO_PREVIOUS_SYNC

构造器详细资料

Extractor

方法详细资料

setSource

getStreamFormat

getTotalStreams

specifyStream

unspecifyStream

rewindTo

next

readBuffer

getStreamId

getFrameTimestamp

getFrameSize

getFrameType

release

finalize