Android音视频开发 - MediaMetadataRetriever 相关

MediaMetadataRetriever 是android中用于从媒体文件中提取元数据新的类. 可以获取音频,视频和图像文件的各种信息,如时长,标题,封面等.

1:初始化对象

private MediaMetadataRetriever mediaMetadataRetriever = new MediaMetadataRetriever();
mediaMetadataRetriever.setDataSource("sdcard/share.mp4");

需要申请读写权限.

这里我使用的是本地路径, 需要注意的是如果路径文件不存在,会抛出

IllegalArgumentException,具体的源码如下:

public void setDataSource(String path) throws IllegalArgumentException {if (path == null) {throw new IllegalArgumentException();}try (FileInputStream is = new FileInputStream(path)) {FileDescriptor fd = is.getFD();setDataSource(fd, 0, 0x7ffffffffffffffL);} catch (FileNotFoundException fileEx) {throw new IllegalArgumentException();} catch (IOException ioEx) {throw new IllegalArgumentException();}
}

2: extractMetadata

根据keyCode返回keyCode关联的元数据.

系统的keyCode如下:

 /*** The metadata key to retrieve the numeric string describing the* order of the audio data source on its original recording.*/public static final int METADATA_KEY_CD_TRACK_NUMBER = 0;/*** The metadata key to retrieve the information about the album title* of the data source.*/public static final int METADATA_KEY_ALBUM           = 1;/*** The metadata key to retrieve the information about the artist of* the data source.*/public static final int METADATA_KEY_ARTIST          = 2;/*** The metadata key to retrieve the information about the author of* the data source.*/public static final int METADATA_KEY_AUTHOR          = 3;/*** The metadata key to retrieve the information about the composer of* the data source.*/public static final int METADATA_KEY_COMPOSER        = 4;/*** The metadata key to retrieve the date when the data source was created* or modified.*/public static final int METADATA_KEY_DATE            = 5;/*** The metadata key to retrieve the content type or genre of the data* source.*/public static final int METADATA_KEY_GENRE           = 6;/*** The metadata key to retrieve the data source title.*/public static final int METADATA_KEY_TITLE           = 7;/*** The metadata key to retrieve the year when the data source was created* or modified.*/public static final int METADATA_KEY_YEAR            = 8;/*** The metadata key to retrieve the playback duration of the data source.*/public static final int METADATA_KEY_DURATION        = 9;/*** 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_NUM_TRACKS      = 10;/*** The metadata key to retrieve the information of the writer (such as* lyricist) of the data source.*/public static final int METADATA_KEY_WRITER          = 11;/*** 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_MIMETYPE        = 12;/*** The metadata key to retrieve the information about the performers or* artist associated with the data source.*/public static final int METADATA_KEY_ALBUMARTIST     = 13;/*** 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_DISC_NUMBER     = 14;/*** The metadata key to retrieve the music album compilation status.*/public static final int METADATA_KEY_COMPILATION     = 15;/*** If this key exists the media contains audio content.*/public static final int METADATA_KEY_HAS_AUDIO       = 16;/*** If this key exists the media contains video content.*/public static final int METADATA_KEY_HAS_VIDEO       = 17;/*** If the media contains video, this key retrieves its width.*/public static final int METADATA_KEY_VIDEO_WIDTH     = 18;/*** If the media contains video, this key retrieves its height.*/public static final int METADATA_KEY_VIDEO_HEIGHT    = 19;/*** This key retrieves the average bitrate (in bits/sec), if available.*/public static final int METADATA_KEY_BITRATE         = 20;/*** This key retrieves the language code of text tracks, if available.* If multiple text tracks present, the return value will look like:* "eng:chi"* @hide*/public static final int METADATA_KEY_TIMED_TEXT_LANGUAGES      = 21;/*** If this key exists the media is drm-protected.* @hide*/public static final int METADATA_KEY_IS_DRM          = 22;/*** This key retrieves the location information, if available.* The location should be specified according to ISO-6709 standard, under* a mp4/3gp box "@xyz". Location with longitude of -90 degrees and latitude* of 180 degrees will be retrieved as "-90.0000+180.0000", for instance.*/public static final int METADATA_KEY_LOCATION        = 23;/*** This key retrieves the video rotation angle in degrees, if available.* The video rotation angle may be 0, 90, 180, or 270 degrees.*/public static final int METADATA_KEY_VIDEO_ROTATION = 24;/*** This key retrieves the original capture framerate, if it's* available. The capture framerate will be a floating point* number.*/public static final int METADATA_KEY_CAPTURE_FRAMERATE = 25;/*** If this key exists the media contains still image content.*/public static final int METADATA_KEY_HAS_IMAGE       = 26;/*** If the media contains still images, this key retrieves the number* of still images.*/public static final int METADATA_KEY_IMAGE_COUNT     = 27;/*** If the media contains still images, this key retrieves the image* index of the primary image.*/public static final int METADATA_KEY_IMAGE_PRIMARY   = 28;/*** If the media contains still images, this key retrieves the width* of the primary image.*/public static final int METADATA_KEY_IMAGE_WIDTH     = 29;/*** If the media contains still images, this key retrieves the height* of the primary image.*/public static final int METADATA_KEY_IMAGE_HEIGHT    = 30;/*** If the media contains still images, this key retrieves the rotation* angle (in degrees clockwise) of the primary image. The image rotation* angle must be one of 0, 90, 180, or 270 degrees.*/public static final int METADATA_KEY_IMAGE_ROTATION  = 31;/*** If the media contains video and this key exists, it retrieves the* total number of frames in the video sequence.*/public static final int METADATA_KEY_VIDEO_FRAME_COUNT = 32;/*** @hide*/public static final int METADATA_KEY_EXIF_OFFSET = 33;/*** @hide*/public static final int METADATA_KEY_EXIF_LENGTH = 34;// Add more here...

如获取视频时长:

String METADATA_KEY_DURATION = mediaMetadataRetriever.extractMetadata(MediaMetadataRetriever.METADATA_KEY_DURATION);
Log.i(TAG, "onCreate: METADATA_KEY_DURATION="+METADATA_KEY_DURATION);

3: getFrameAtTime

该方法在任何时间位置找到一个有代表性的帧，并将其作为位图返回.

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {Bitmap frameAtTime =         mediaMetadataRetriever.getFrameAtTime();
}

如果需要获取指定时间,则可以调用

 public Bitmap getFrameAtTime(long timeUs) {return getFrameAtTime(timeUs, OPTION_CLOSEST_SYNC);}

4: getFrameAtIndex

用于从媒体文件中获取指定索引位置的帧图像.

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {Bitmap frameAtIndex = mediaMetadataRetriever.getFrameAtIndex(0);
}

5: getImageAtIndex

基于0的图像索引,返回位图信息.

Bitmap imageAtIndex = mediaMetadataRetriever.getImageAtIndex(0);

这里调用该方法时,会抛出IllegalStateException :

  java.lang.IllegalStateException: Does not contail still imagesat android.media.MediaMetadataRetriever.getImageAtIndexInternal(MediaMetadataRetriever.java:648)at android.media.MediaMetadataRetriever.getImageAtIndex(MediaMetadataRetriever.java:605)at com.test.media.MainActivity.lambda$onCreate$0$MainActivity(MainActivity.java:50)at com.test.media.-$$Lambda$MainActivity$fGcBDHveSBN77vUeMp6H1nheePE.onClick(Unknown Source:2)at android.view.View.performClick(View.java:7259)at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:967)at android.view.View.performClickInternal(View.java:7236)at android.view.View.access$3600(View.java:801)at android.view.View$PerformClick.run(View.java:27892)at android.os.Handler.handleCallback(Handler.java:894)at android.os.Handler.dispatchMessage(Handler.java:106)at android.os.Looper.loop(Looper.java:214)at android.app.ActivityThread.main(ActivityThread.java:7356)at java.lang.reflect.Method.invoke(Native Method)at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:491)at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:940)

具体的错误信息的原因如下:

private Bitmap getImageAtIndexInternal(int imageIndex, @Nullable BitmapParams params) {if (!"yes".equals(extractMetadata(MediaMetadataRetriever.METADATA_KEY_HAS_IMAGE))) {throw new IllegalStateException("Does not contail still images");}String imageCount = extractMetadata(MediaMetadataRetriever.METADATA_KEY_IMAGE_COUNT);if (imageIndex >= Integer.parseInt(imageCount)) {throw new IllegalArgumentException("Invalid image index: " + imageCount);}return _getImageAtIndex(imageIndex, params);
}

可以看到系统源码中校验了extractMetadata(MediaMetadataRetriever.METADATA_KEY_HAS_IMAGE)的值,如果值不是"yes",就会抛出"Does not contail still images".

与getImageAtIndex类似的方法还有:

getImageAtIndex(int, BitmapParams)
getPrimaryImage(BitmapParams)
getPrimaryImage()