Android example source code file (MediaMetadataRetriever.java)

This example Android source code file (MediaMetadataRetriever.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, content, contentresolver, illegalargumentexception, internet, io, mediametadataretriever, metadata_key_author, metadata_key_bit_rate, metadata_key_discnumber, metadata_key_duration, metadata_key_title, metadata_key_video_width, metadata_key_writer, mode_capture_frame_only, net, network, override, securityexception, string

The MediaMetadataRetriever.java Android example source code

/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.media;

import android.content.ContentResolver;
import android.content.Context;
import android.content.res.AssetFileDescriptor;
import android.graphics.Bitmap;
import android.net.Uri;

import java.io.FileDescriptor;
import java.io.FileNotFoundException;
import java.io.IOException;

/**
 * MediaMetadataRetriever class provides a unified interface for retrieving
 * frame and meta data from an input media file.
 * {@hide}
 */
public class MediaMetadataRetriever
{
    static {
        System.loadLibrary("media_jni");
        native_init();
    }

    // The field below is accessed by native methods
    @SuppressWarnings("unused")
    private int mNativeContext;
 
    public MediaMetadataRetriever() {
        native_setup();
    }

    /**
     * Call this method before setDataSource() so that the mode becomes
     * effective for subsequent operations. This method can be called only once
     * at the beginning if the intended mode of operation for a
     * MediaMetadataRetriever object remains the same for its whole lifetime,
     * and thus it is unnecessary to call this method each time setDataSource()
     * is called. If this is not never called (which is allowed), by default the
     * intended mode of operation is to both capture frame and retrieve meta
     * data (i.e., MODE_GET_METADATA_ONLY | MODE_CAPTURE_FRAME_ONLY).
     * Often, this may not be what one wants, since doing this has negative
     * performance impact on execution time of a call to setDataSource(), since
     * both types of operations may be time consuming.
     * 
     * @param mode The intended mode of operation. Can be any combination of 
     * MODE_GET_METADATA_ONLY and MODE_CAPTURE_FRAME_ONLY:
     * 1. MODE_GET_METADATA_ONLY & MODE_CAPTURE_FRAME_ONLY: 
     *    For neither frame capture nor meta data retrieval
     * 2. MODE_GET_METADATA_ONLY: For meta data retrieval only
     * 3. MODE_CAPTURE_FRAME_ONLY: For frame capture only
     * 4. MODE_GET_METADATA_ONLY | MODE_CAPTURE_FRAME_ONLY: 
     *    For both frame capture and meta data retrieval
     */
    public native void setMode(int mode);
    
    /**
     * @return the current mode of operation. A negative return value indicates
     * some runtime error has occurred.
     */
    public native int getMode();

    /**
     * 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.
     * 
     * @param path The path of the input media file.
     * @throws IllegalArgumentException If the path is invalid.
     */
    public native void setDataSource(String path) throws IllegalArgumentException;
    
    /**
     * 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.
     * 
     * @param fd the FileDescriptor for the file you want to play
     * @param offset the offset into the file where the data to be played starts,
     * in bytes. It must be non-negative
     * @param length the length in bytes of the data to be played. It must be
     * non-negative.
     * @throws IllegalArgumentException if the arguments are invalid
     */
    public native void setDataSource(FileDescriptor fd, long offset, long length)
            throws IllegalArgumentException;
    
    /**
     * 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.
     * 
     * @param fd the FileDescriptor for the file you want to play
     * @throws IllegalArgumentException if the FileDescriptor is invalid
     */
    public void setDataSource(FileDescriptor fd)
            throws IllegalArgumentException {
        // intentionally less than LONG_MAX
        setDataSource(fd, 0, 0x7ffffffffffffffL);
    }
    
    /**
     * 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.
     * 
     * @param context the Context to use when resolving the Uri
     * @param uri the Content URI of the data you want to play
     * @throws IllegalArgumentException if the Uri is invalid
     * @throws SecurityException if the Uri cannot be used due to lack of
     * permission.
     */
    public void setDataSource(Context context, Uri uri)
        throws IllegalArgumentException, SecurityException {
        if (uri == null) {
            throw new IllegalArgumentException();
        }
        
        String scheme = uri.getScheme();
        if(scheme == null || scheme.equals("file")) {
            setDataSource(uri.getPath());
            return;
        }

        AssetFileDescriptor fd = null;
        try {
            ContentResolver resolver = context.getContentResolver();
            try {
                fd = resolver.openAssetFileDescriptor(uri, "r");
            } catch(FileNotFoundException e) {
                throw new IllegalArgumentException();
            }
            if (fd == null) {
                throw new IllegalArgumentException();
            }
            FileDescriptor descriptor = fd.getFileDescriptor();
            if (!descriptor.valid()) {
                throw new IllegalArgumentException();
            }
            // Note: using getDeclaredLength so that our behavior is the same
            // as previous versions when the content provider is returning
            // a full file.
            if (fd.getDeclaredLength() < 0) {
                setDataSource(descriptor);
            } else {
                setDataSource(descriptor, fd.getStartOffset(), fd.getDeclaredLength());
            }
            return;
        } catch (SecurityException ex) {
        } finally {
            try {
                if (fd != null) {
                    fd.close();
                }
            } catch(IOException ioEx) {
            }
        }
        setDataSource(uri.toString());
    }

    /**
     * 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.
     * 
     * @param keyCode One of the constants listed below at the end of the class.
     * @return The meta data value associate with the given keyCode on success; 
     * null on failure.
     */
    public native String extractMetadata(int keyCode);

    /**
     * Call this method after setDataSource(). This method finds a
     * representative frame if successful and returns it as a bitmap. This is
     * useful for generating a thumbnail for an input media source.
     * 
     * @return A Bitmap containing a representative video frame, which 
     *         can be null, if such a frame cannot be retrieved.
     */
    public native Bitmap captureFrame();
    
    /**
     * Call this method after setDataSource(). This method finds the optional
     * graphic or album art associated (embedded or external url linked) the 
     * related data source.
     * 
     * @return null if no such graphic is found.
     */
    public native byte[] extractAlbumArt();

    /**
     * Call it when one is done with the object. This method releases the memory
     * allocated internally.
     */
    public native void release();
    private native void native_setup();
    private static native void native_init();

    private native final void native_finalize();

    @Override
    protected void finalize() throws Throwable {
        try {
            native_finalize();
        } finally {
            super.finalize();
        }
    }

    public static final int MODE_GET_METADATA_ONLY  = 0x01;
    public static final int MODE_CAPTURE_FRAME_ONLY = 0x02;

    /*
     * Do not change these values without updating their counterparts
     * in include/media/mediametadataretriever.h!
     */
    public static final int METADATA_KEY_CD_TRACK_NUMBER = 0;
    public static final int METADATA_KEY_ALBUM           = 1;
    public static final int METADATA_KEY_ARTIST          = 2;
    public static final int METADATA_KEY_AUTHOR          = 3;
    public static final int METADATA_KEY_COMPOSER        = 4;
    public static final int METADATA_KEY_DATE            = 5;
    public static final int METADATA_KEY_GENRE           = 6;
    public static final int METADATA_KEY_TITLE           = 7;
    public static final int METADATA_KEY_YEAR            = 8;
    public static final int METADATA_KEY_DURATION        = 9;
    public static final int METADATA_KEY_NUM_TRACKS      = 10;
    public static final int METADATA_KEY_IS_DRM_CRIPPLED = 11;
    public static final int METADATA_KEY_CODEC           = 12;
    public static final int METADATA_KEY_RATING          = 13;
    public static final int METADATA_KEY_COMMENT         = 14;
    public static final int METADATA_KEY_COPYRIGHT       = 15;
    public static final int METADATA_KEY_BIT_RATE        = 16;
    public static final int METADATA_KEY_FRAME_RATE      = 17;
    public static final int METADATA_KEY_VIDEO_FORMAT    = 18;
    public static final int METADATA_KEY_VIDEO_HEIGHT    = 19;
    public static final int METADATA_KEY_VIDEO_WIDTH     = 20;
    public static final int METADATA_KEY_WRITER          = 21;
    public static final int METADATA_KEY_MIMETYPE        = 22;
    public static final int METADATA_KEY_DISCNUMBER      = 23;
    public static final int METADATA_KEY_ALBUMARTIST     = 24;
    // Add more here...
}