MediaMetadataRetriever
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
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| 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. |
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| 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. |
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| 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. |
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| 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. |
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| 公有构造函数 | |||||||||||
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| MediaMetadataRetriever() | |||||||||||
| 公有方法 | |||||||||||
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| String | extractMetadata(int keyCode)
Call this method after setDataSource().
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| byte[] | getEmbeddedPicture()
Call this method after setDataSource().
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| Bitmap | getFrameAtTime(long timeUs, int option)
Call this method after setDataSource().
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| Bitmap | getFrameAtTime(long timeUs)
Call this method after setDataSource().
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| Bitmap | getFrameAtTime()
Call this method after setDataSource().
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| void | release()
Call it when one is done with the object.
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| void | setDataSource( FileDescriptor fd, long offset, long length)
Sets the data source (FileDescriptor) to use.
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| void | setDataSource( String path)
Sets the data source (file pathname) to use.
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| void | setDataSource( FileDescriptor fd)
Sets the data source (FileDescriptor) to use.
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| void | setDataSource( Context context, Uri uri)
Sets the data source as a content Uri.
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| 保护方法 | |||||||||||
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| void | finalize()
Called before the object's memory is reclaimed by the VM.
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| [展开]
继承的方法
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| 来自 class java.lang.Object
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常量
public static final int METADATA_KEY_ALBUM
The metadata key to retrieve the information about the album title of the data source.
public static final int METADATA_KEY_ALBUMARTIST
The metadata key to retrieve the information about the performers or artist associated with the data source.
public static final int METADATA_KEY_ARTIST
The metadata key to retrieve the information about the artist of the data source.
public static final int METADATA_KEY_AUTHOR
The metadata key to retrieve the information about the author of the data source.
public static final 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.
public static final int METADATA_KEY_COMPILATION
The metadata key to retrieve the music album compilation status.
public static final int METADATA_KEY_COMPOSER
The metadata key to retrieve the information about the composer of the data source.
public static final int METADATA_KEY_DATE
The metadata key to retrieve the date when the data source was created or modified.
public static final 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.
public static final int METADATA_KEY_DURATION
The metadata key to retrieve the playback duration of the data source.
public static final int METADATA_KEY_GENRE
The metadata key to retrieve the content type or genre of the data source.
public static final int METADATA_KEY_MIMETYPE
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.
public static final 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.
public static final int METADATA_KEY_TITLE
The metadata key to retrieve the data source title.
public static final int METADATA_KEY_WRITER
The metadata key to retrieve the information of the writer (such as lyricist) of the data source.
public static final int METADATA_KEY_YEAR
The metadata key to retrieve the year when the data source was created or modified.
public static final 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.
参见
getFrameAtTime(long, int)
public static final 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.
参见
getFrameAtTime(long, int)
public static final 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.
参见
getFrameAtTime(long, int)
public static final 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.
参见
getFrameAtTime(long, int)
公有构造函数
public MediaMetadataRetriever ()
公有方法
public String extractMetadata (int keyCode)
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. |
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返回值
- The meta data value associate with the given keyCode on success; null on failure.
public byte[] getEmbeddedPicture ()
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)
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. |
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| 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)
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. |
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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 ()
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 ()
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)
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 |
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| 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 |
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public void setDataSource (String path)
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. |
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抛出
| IllegalArgumentException | If the path is invalid. |
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public void setDataSource (FileDescriptor fd)
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 |
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抛出
| IllegalArgumentException | if the FileDescriptor is invalid |
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public void setDataSource (Context context, Uri uri)
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 |
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| uri | the Content URI of the data you want to play |
抛出
| IllegalArgumentException | if the Uri is invalid |
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| SecurityException | if the Uri cannot be used due to lack of permission. |
保护方法
protected void finalize ()
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 |
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