MediaMetadataRetriever

public class

MediaMetadataRetriever

extends Object

java.lang.Object
↳	android.media.MediaMetadataRetriever

类概述

MediaMetadataRetriever class provides a unified interface for retrieving frame and meta data from an input media file.

摘要

常量
int	METADATA_KEY_ALBUM	The metadata key to retrieve the information about the album title of the data source.
int	METADATA_KEY_ALBUMARTIST	The metadata key to retrieve the information about the performers or artist associated with the data source.
int	METADATA_KEY_ARTIST	The metadata key to retrieve the information about the artist of the data source.
int	METADATA_KEY_AUTHOR	The metadata key to retrieve the information about the author of the data source.
int	METADATA_KEY_CD_TRACK_NUMBER	The metadata key to retrieve the numberic string describing the order of the audio data source on its original recording.
int	METADATA_KEY_COMPILATION	The metadata key to retrieve the music album compilation status.
int	METADATA_KEY_COMPOSER	The metadata key to retrieve the information about the composer of the data source.
int	METADATA_KEY_DATE	The metadata key to retrieve the date when the data source was created or modified.
int	METADATA_KEY_DISC_NUMBER	The metadata key to retrieve the numberic string that describes which part of a set the audio data source comes from.
int	METADATA_KEY_DURATION	The metadata key to retrieve the playback duration of the data source.
int	METADATA_KEY_GENRE	The metadata key to retrieve the content type or genre of the data source.
int	METADATA_KEY_MIMETYPE	The metadata key to retrieve the mime type of the data source.
int	METADATA_KEY_NUM_TRACKS	The metadata key to retrieve the number of tracks, such as audio, video, text, in the data source, such as a mp4 or 3gpp file.
int	METADATA_KEY_TITLE	The metadata key to retrieve the data source title.
int	METADATA_KEY_WRITER	The metadata key to retrieve the information of the writer (such as lyricist) of the data source.
int	METADATA_KEY_YEAR	The metadata key to retrieve the year when the data source was created or modified.
int	OPTION_CLOSEST	This option is used with  getFrameAtTime(long, int)  to retrieve a frame (not necessarily a key frame) associated with a data source that is located closest to or at the given time.
int	OPTION_CLOSEST_SYNC	This option is used with  getFrameAtTime(long, int)  to retrieve a sync (or key) frame associated with a data source that is located closest to (in time) or at the given time.
int	OPTION_NEXT_SYNC	This option is used with  getFrameAtTime(long, int)  to retrieve a sync (or key) frame associated with a data source that is located right after or at the given time.
int	OPTION_PREVIOUS_SYNC	This option is used with  getFrameAtTime(long, int)  to retrieve a sync (or key) frame associated with a data source that is located right before or at the given time.

公有构造函数
	MediaMetadataRetriever()

公有方法
String	extractMetadata(int keyCode)Call this method after setDataSource().
byte[]	getEmbeddedPicture()Call this method after setDataSource().
Bitmap	getFrameAtTime(long timeUs, int option)Call this method after setDataSource().
Bitmap	getFrameAtTime(long timeUs)Call this method after setDataSource().
Bitmap	getFrameAtTime()Call this method after setDataSource().
void	release()Call it when one is done with the object.
void	setDataSource(FileDescriptor fd, long offset, long length)Sets the data source (FileDescriptor) to use.
void	setDataSource(String path)Sets the data source (file pathname) to use.
void	setDataSource(FileDescriptor fd)Sets the data source (FileDescriptor) to use.
void	setDataSource(Context context, Uri uri)Sets the data source as a content Uri.

保护方法
void	finalize()Called before the object's memory is reclaimed by the VM.

[展开] 继承的方法
来自 class java.lang.Object

常量

public static final int METADATA_KEY_ALBUM

引入自：API 级别10

The metadata key to retrieve the information about the album title of the data source.

常量值： 1 (0x00000001)

public static final int METADATA_KEY_ALBUMARTIST

引入自：API 级别10

The metadata key to retrieve the information about the performers or artist associated with the data source.

常量值： 13 (0x0000000d)

public static final int METADATA_KEY_ARTIST

引入自：API 级别10

The metadata key to retrieve the information about the artist of the data source.

常量值： 2 (0x00000002)

public static final int METADATA_KEY_AUTHOR

引入自：API 级别10

The metadata key to retrieve the information about the author of the data source.

常量值： 3 (0x00000003)

public static final int METADATA_KEY_CD_TRACK_NUMBER

引入自：API 级别10

The metadata key to retrieve the numberic string describing the order of the audio data source on its original recording.

常量值： 0 (0x00000000)

public static final int METADATA_KEY_COMPILATION

引入自：API 级别10

The metadata key to retrieve the music album compilation status.

常量值： 15 (0x0000000f)

public static final int METADATA_KEY_COMPOSER

引入自：API 级别10

The metadata key to retrieve the information about the composer of the data source.

常量值： 4 (0x00000004)

public static final int METADATA_KEY_DATE

引入自：API 级别10

The metadata key to retrieve the date when the data source was created or modified.

常量值： 5 (0x00000005)

public static final int METADATA_KEY_DISC_NUMBER

引入自：API 级别10

The metadata key to retrieve the numberic string that describes which part of a set the audio data source comes from.

常量值： 14 (0x0000000e)

public static final int METADATA_KEY_DURATION

引入自：API 级别10

The metadata key to retrieve the playback duration of the data source.

常量值： 9 (0x00000009)

public static final int METADATA_KEY_GENRE

引入自：API 级别10

The metadata key to retrieve the content type or genre of the data source.

常量值： 6 (0x00000006)

public static final int METADATA_KEY_MIMETYPE

引入自：API 级别10

The metadata key to retrieve the mime type of the data source. Some example mime types include: "video/mp4", "audio/mp4", "audio/amr-wb", etc.

常量值： 12 (0x0000000c)

public static final int METADATA_KEY_NUM_TRACKS

引入自：API 级别10

The metadata key to retrieve the number of tracks, such as audio, video, text, in the data source, such as a mp4 or 3gpp file.

常量值： 10 (0x0000000a)

public static final int METADATA_KEY_TITLE

引入自：API 级别10

The metadata key to retrieve the data source title.

常量值： 7 (0x00000007)

public static final int METADATA_KEY_WRITER

引入自：API 级别10

The metadata key to retrieve the information of the writer (such as lyricist) of the data source.

常量值： 11 (0x0000000b)

public static final int METADATA_KEY_YEAR

引入自：API 级别10

The metadata key to retrieve the year when the data source was created or modified.

常量值： 8 (0x00000008)

public static final int OPTION_CLOSEST

引入自：API 级别10

This option is used with 

getFrameAtTime(long, int)

 to
retrieve a frame (not necessarily a key frame) associated with a data source that is located closest to or at the given time.


参见

getFrameAtTime(long,
int)

常量值： 3 (0x00000003)

public static final int OPTION_CLOSEST_SYNC

引入自：API 级别10

This option is used with 

getFrameAtTime(long, int)

 to
retrieve a sync (or key) frame associated with a data source that is located closest to (in time) or at the given time.


参见

getFrameAtTime(long,
int)

常量值： 2 (0x00000002)

public static final int OPTION_NEXT_SYNC

引入自：API 级别10

This option is used with 

getFrameAtTime(long, int)

 to
retrieve a sync (or key) frame associated with a data source that is located right after or at the given time.


参见

getFrameAtTime(long,
int)

常量值： 1 (0x00000001)

public static final int OPTION_PREVIOUS_SYNC

引入自：API 级别10

This option is used with 

getFrameAtTime(long, int)

 to
retrieve a sync (or key) frame associated with a data source that is located right before or at the given time.


参见

getFrameAtTime(long,
int)

常量值： 0 (0x00000000)

公有构造函数

public MediaMetadataRetriever ()

引入自：API 级别10

公有方法

public String extractMetadata (int
keyCode)

引入自：API 级别10

Call this method after setDataSource(). This method retrieves the meta data value associated with the keyCode. The keyCode currently supported is listed below as METADATA_XXX constants. With any other value, it returns a null pointer.


参数

keyCode	One of the constants listed below at the end of the class.

返回值
The meta data value associate with the given keyCode on success; null on failure.

public byte[] getEmbeddedPicture ()

引入自：API 级别10

Call this method after setDataSource(). This method finds the optional graphic or album art associated associated with the data source. If there are more than one pictures, (any) one of them is returned.


返回值
null if no such graphic is found.

public Bitmap getFrameAtTime (long
timeUs, int option)

引入自：API 级别10

Call this method after setDataSource(). This method finds a representative frame close to the given time position by considering the given option if possible, and returns it as a bitmap. This is useful for generating a thumbnail for an input data source or
just obtain and display a frame at the given time position.


参数

timeUs

The time position where the frame will be retrieved. When retrieving the frame at the given time position, there is no guarantee that the data source has a frame located at the position. When this happens, a frame nearby will be returned. If timeUs is negative, time position and option will ignored, and any frame that the implementation considers as representative may be returned.

option

a hint on how the frame is found. Use  OPTION_PREVIOUS_SYNC  if one wants to retrieve a sync frame that has a timestamp earlier than or the same as timeUs. Use  OPTION_NEXT_SYNC  if one wants to retrieve a sync frame that has a timestamp later than or the same as timeUs. Use  OPTION_CLOSEST_SYNC  if one wants to retrieve a sync frame that has a timestamp closest to or the same as timeUs. Use  OPTION_CLOSEST  if one wants to retrieve a frame that may or may not be a sync frame but is closest to or the same as timeUs.  OPTION_CLOSEST  often has larger performance overhead compared to the other options if there is no sync frame located at timeUs.

返回值
A Bitmap containing a representative video frame, which can be null, if such a frame cannot be retrieved.

public Bitmap getFrameAtTime (long
timeUs)

引入自：API 级别10

Call this method after setDataSource(). This method finds a representative frame close to the given time position if possible, and returns it as a bitmap. This is useful for generating a thumbnail for an input data source. Call this method if one does not care
how the frame is found as long as it is close to the given time; otherwise, please call 

getFrameAtTime(long,
int)

.


参数

timeUs	The time position where the frame will be retrieved. When retrieving the frame at the given time position, there is no guarentee that the data source has a frame located at the position. When this happens, a frame nearby will be returned. If timeUs is negative, time position and option will ignored, and any frame that the implementation considers as representative may be returned.

返回值
A Bitmap containing a representative video frame, which can be null, if such a frame cannot be retrieved.


参见

getFrameAtTime(long,
int)

public Bitmap getFrameAtTime ()

引入自：API 级别10

Call this method after setDataSource(). This method finds a representative frame at any time position if possible, and returns it as a bitmap. This is useful for generating a thumbnail for an input data source. Call this method if one does not care about where
the frame is located; otherwise, please call 

getFrameAtTime(long)

 or 

getFrameAtTime(long,
int)

返回值
A Bitmap containing a representative video frame, which can be null, if such a frame cannot be retrieved.


参见

getFrameAtTime(long)

getFrameAtTime(long,
int)

public void release ()

引入自：API 级别10

Call it when one is done with the object. This method releases the memory allocated internally.

public void setDataSource (FileDescriptor fd,
long offset, long length)

引入自：API 级别10

Sets the data source (FileDescriptor) to use. It is the caller's responsibility to close the file descriptor. It is safe to do so as soon as this call returns. Call this method before the rest of the methods in this class. This method may be time-consuming.


参数

fd	the FileDescriptor for the file you want to play
offset	the offset into the file where the data to be played starts, in bytes. It must be non-negative
length	the length in bytes of the data to be played. It must be non-negative.

抛出

IllegalArgumentException	if the arguments are invalid

public void setDataSource (String path)

引入自：API 级别10

Sets the data source (file pathname) to use. Call this method before the rest of the methods in this class. This method may be time-consuming.


参数

path	The path of the input media file.

抛出

IllegalArgumentException	If the path is invalid.

public void setDataSource (FileDescriptor fd)

引入自：API 级别10

Sets the data source (FileDescriptor) to use. It is the caller's responsibility to close the file descriptor. It is safe to do so as soon as this call returns. Call this method before the rest of the methods in this class. This method may be time-consuming.


参数

fd	the FileDescriptor for the file you want to play

抛出

IllegalArgumentException	if the FileDescriptor is invalid

public void setDataSource (Context context, Uri uri)

引入自：API 级别10

Sets the data source as a content Uri. Call this method before the rest of the methods in this class. This method may be time-consuming.


参数

context	the Context to use when resolving the Uri
uri	the Content URI of the data you want to play

抛出

IllegalArgumentException	if the Uri is invalid
SecurityException	if the Uri cannot be used due to lack of permission.

保护方法

protected void finalize ()

引入自：API 级别10

Called before the object's memory is reclaimed by the VM. This can only happen once the garbage collector has detected that the object is no longer reachable by any thread of the running application.

The method can be used to free system resources or perform other cleanup before the object is garbage collected. The default implementation of the method is empty, which is also expected by the VM, but subclasses can override 

finalize()

 as
required. Uncaught exceptions which are thrown during the execution of this method cause it to terminate immediately but are otherwise ignored.

Note that the VM does guarantee that 

finalize()

 is called at most once for any object, but it doesn't guarantee when (if at all) 

finalize()

 will
be called. For example, object B's 

finalize()

 can delay the execution of object A's 

finalize()

 method and therefore it can delay the reclamation
of A's memory. To be safe, use a 

ReferenceQueue

, because it provides more
control over the way the VM deals with references during garbage collection.


抛出

Throwable