android/media/MediaExtractor.java

/*
 * Copyright (C) 2012 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.annotation.IntDef;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.content.ContentResolver;
import android.content.Context;
import android.content.res.AssetFileDescriptor;
import android.media.MediaCodec;
import android.media.MediaFormat;
import android.media.MediaHTTPService;
import android.net.Uri;
import android.os.IBinder;
import android.os.IHwBinder;
import android.os.PersistableBundle;

import com.android.internal.util.Preconditions;

import java.io.FileDescriptor;
import java.io.IOException;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import java.util.UUID;

/**
 * MediaExtractor facilitates extraction of demuxed, typically encoded,  media data
 * from a data source.
 * <p>It is generally used like this:
 * <pre>
 * MediaExtractor extractor = new MediaExtractor();
 * extractor.setDataSource(...);
 * int numTracks = extractor.getTrackCount();
 * for (int i = 0; i &lt; numTracks; ++i) {
 *   MediaFormat format = extractor.getTrackFormat(i);
 *   String mime = format.getString(MediaFormat.KEY_MIME);
 *   if (weAreInterestedInThisTrack) {
 *     extractor.selectTrack(i);
 *   }
 * }
 * ByteBuffer inputBuffer = ByteBuffer.allocate(...)
 * while (extractor.readSampleData(inputBuffer, ...) &gt;= 0) {
 *   int trackIndex = extractor.getSampleTrackIndex();
 *   long presentationTimeUs = extractor.getSampleTime();
 *   ...
 *   extractor.advance();
 * }
 *
 * extractor.release();
 * extractor = null;
 * </pre>
 *
 * <p>This class requires the {@link android.Manifest.permission#INTERNET} permission
 * when used with network-based content.
 */
final public class MediaExtractor {
    public MediaExtractor() {
        native_setup();
    }

    /**
     * Sets the data source (MediaDataSource) to use.
     *
     * @param dataSource the MediaDataSource for the media you want to extract from
     *
     * @throws IllegalArgumentException if dataSource is invalid.
     */
    public native final void setDataSource(@NonNull MediaDataSource dataSource)
        throws IOException;

    /**
     * Sets the data source as a content Uri.
     *
     * @param context the Context to use when resolving the Uri
     * @param uri the Content URI of the data you want to extract from.
     *
     * <p>When <code>uri</code> refers to a network file the
     * {@link android.Manifest.permission#INTERNET} permission is required.
     *
     * @param headers the headers to be sent together with the request for the data.
     *        This can be {@code null} if no specific headers are to be sent with the
     *        request.
     */
    public final void setDataSource(
            @NonNull Context context, @NonNull Uri uri, @Nullable Map<String, String> headers)
        throws IOException {
        String scheme = uri.getScheme();
        if (scheme == null || scheme.equals("file")) {
            setDataSource(uri.getPath());
            return;
        }

        AssetFileDescriptor fd = null;
        try {
            ContentResolver resolver = context.getContentResolver();
            fd = resolver.openAssetFileDescriptor(uri, "r");
            if (fd == null) {
                return;
            }
            // 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(fd.getFileDescriptor());
            } else {
                setDataSource(
                        fd.getFileDescriptor(),
                        fd.getStartOffset(),
                        fd.getDeclaredLength());
            }
            return;
        } catch (SecurityException ex) {
        } catch (IOException ex) {
        } finally {
            if (fd != null) {
                fd.close();
            }
        }

        setDataSource(uri.toString(), headers);
    }

    /**
     * Sets the data source (file-path or http URL) to use.
     *
     * @param path the path of the file, or the http URL
     *
     * <p>When <code>path</code> refers to a network file the
     * {@link android.Manifest.permission#INTERNET} permission is required.
     *
     * @param headers the headers associated with the http request for the stream you want to play.
     *        This can be {@code null} if no specific headers are to be sent with the
     *        request.
     */
    public final void setDataSource(@NonNull String path, @Nullable Map<String, String> headers)
        throws IOException {
        String[] keys = null;
        String[] values = null;

        if (headers != null) {
            keys = new String[headers.size()];
            values = new String[headers.size()];

            int i = 0;
            for (Map.Entry<String, String> entry: headers.entrySet()) {
                keys[i] = entry.getKey();
                values[i] = entry.getValue();
                ++i;
            }
        }

        nativeSetDataSource(
                MediaHTTPService.createHttpServiceBinderIfNecessary(path),
                path,
                keys,
                values);
    }

    private native final void nativeSetDataSource(
            @NonNull IBinder httpServiceBinder,
            @NonNull String path,
            @Nullable String[] keys,
            @Nullable String[] values) throws IOException;

    /**
     * Sets the data source (file-path or http URL) to use.
     *
     * @param path the path of the file, or the http URL of the stream
     *
     * <p>When <code>path</code> refers to a local file, the file may actually be opened by a
     * process other than the calling application.  This implies that the pathname
     * should be an absolute path (as any other process runs with unspecified current working
     * directory), and that the pathname should reference a world-readable file.
     * As an alternative, the application could first open the file for reading,
     * and then use the file descriptor form {@link #setDataSource(FileDescriptor)}.
     *
     * <p>When <code>path</code> refers to a network file the
     * {@link android.Manifest.permission#INTERNET} permission is required.
     */
    public final void setDataSource(@NonNull String path) throws IOException {
        nativeSetDataSource(
                MediaHTTPService.createHttpServiceBinderIfNecessary(path),
                path,
                null,
                null);
    }

    /**
     * Sets the data source (AssetFileDescriptor) 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.
     *
     * @param afd the AssetFileDescriptor for the file you want to extract from.
     */
    public final void setDataSource(@NonNull AssetFileDescriptor afd)
            throws IOException, IllegalArgumentException, IllegalStateException {
        Preconditions.checkNotNull(afd);
        // Note: using getDeclaredLength so that our behavior is the same
        // as previous versions when the content provider is returning
        // a full file.
        if (afd.getDeclaredLength() < 0) {
            setDataSource(afd.getFileDescriptor());
        } else {
            setDataSource(afd.getFileDescriptor(), afd.getStartOffset(), afd.getDeclaredLength());
        }
    }

    /**
     * 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.
     *
     * @param fd the FileDescriptor for the file you want to extract from.
     */
    public final void setDataSource(@NonNull FileDescriptor fd) throws IOException {
        setDataSource(fd, 0, 0x7ffffffffffffffL);
    }

    /**
     * Sets the data source (FileDescriptor) to use.  The FileDescriptor must be
     * seekable (N.B. a LocalSocket is not seekable). It is the caller's responsibility
     * to close the file descriptor. It is safe to do so as soon as this call returns.
     *
     * @param fd the FileDescriptor for the file you want to extract from.
     * @param offset the offset into the file where the data to be extracted starts, in bytes
     * @param length the length in bytes of the data to be extracted
     */
    public native final void setDataSource(
            @NonNull FileDescriptor fd, long offset, long length) throws IOException;

    /**
     * Sets the MediaCas instance to use. This should be called after a
     * successful setDataSource() if at least one track reports mime type
     * of {@link android.media.MediaFormat#MIMETYPE_AUDIO_SCRAMBLED}
     * or {@link android.media.MediaFormat#MIMETYPE_VIDEO_SCRAMBLED}.
     * Stream parsing will not proceed until a valid MediaCas object
     * is provided.
     *
     * @param mediaCas the MediaCas object to use.
     */
    public final void setMediaCas(@NonNull MediaCas mediaCas) {
        mMediaCas = mediaCas;
        nativeSetMediaCas(mediaCas.getBinder());
    }

    private native final void nativeSetMediaCas(@NonNull IHwBinder casBinder);

    /**
     * Describes the conditional access system used to scramble a track.
     */
    public static final class CasInfo {
        private final int mSystemId;
        private final MediaCas.Session mSession;

        CasInfo(int systemId, @Nullable MediaCas.Session session) {
            mSystemId = systemId;
            mSession = session;
        }

        /**
         * Retrieves the system id of the conditional access system.
         *
         * @return CA system id of the CAS used to scramble the track.
         */
        public int getSystemId() {
            return mSystemId;
        }

        /**
         * Retrieves the {@link MediaCas.Session} associated with a track. The
         * session is needed to initialize a descrambler in order to decode the
         * scrambled track.
         * <p>
         * @see MediaDescrambler#setMediaCasSession
         * <p>
         * @return a {@link MediaCas.Session} object associated with a track.
         */
        public MediaCas.Session getSession() {
            return mSession;
        }
    }

    private ArrayList<Byte> toByteArray(@NonNull byte[] data) {
        ArrayList<Byte> byteArray = new ArrayList<Byte>(data.length);
        for (int i = 0; i < data.length; i++) {
            byteArray.add(i, Byte.valueOf(data[i]));
        }
        return byteArray;
    }

    /**
     * Retrieves the information about the conditional access system used to scramble
     * a track.
     *
     * @param index of the track.
     * @return an {@link CasInfo} object describing the conditional access system.
     */
    public CasInfo getCasInfo(int index) {
        Map<String, Object> formatMap = getTrackFormatNative(index);
        if (formatMap.containsKey(MediaFormat.KEY_CA_SYSTEM_ID)) {
            int systemId = ((Integer)formatMap.get(MediaFormat.KEY_CA_SYSTEM_ID)).intValue();
            MediaCas.Session session = null;
            if (mMediaCas != null && formatMap.containsKey(MediaFormat.KEY_CA_SESSION_ID)) {
                ByteBuffer buf = (ByteBuffer) formatMap.get(MediaFormat.KEY_CA_SESSION_ID);
                buf.rewind();
                final byte[] sessionId = new byte[buf.remaining()];
                buf.get(sessionId);
                session = mMediaCas.createFromSessionId(toByteArray(sessionId));
            }
            return new CasInfo(systemId, session);
        }
        return null;
    }

    @Override
    protected void finalize() {
        native_finalize();
    }

    /**
     * Make sure you call this when you're done to free up any resources
     * instead of relying on the garbage collector to do this for you at
     * some point in the future.
     */
    public native final void release();

    /**
     * Count the number of tracks found in the data source.
     */
    public native final int getTrackCount();

    /**
     * Extract DRM initialization data if it exists
     *
     * @return DRM initialization data in the content, or {@code null}
     * if no recognizable DRM format is found;
     * @see DrmInitData
     */
    public DrmInitData getDrmInitData() {
        Map<String, Object> formatMap = getFileFormatNative();
        if (formatMap == null) {
            return null;
        }
        if (formatMap.containsKey("pssh")) {
            Map<UUID, byte[]> psshMap = getPsshInfo();
            final Map<UUID, DrmInitData.SchemeInitData> initDataMap =
                new HashMap<UUID, DrmInitData.SchemeInitData>();
            for (Map.Entry<UUID, byte[]> e: psshMap.entrySet()) {
                UUID uuid = e.getKey();
                byte[] data = e.getValue();
                initDataMap.put(uuid, new DrmInitData.SchemeInitData("cenc", data));
            }
            return new DrmInitData() {
                public SchemeInitData get(UUID schemeUuid) {
                    return initDataMap.get(schemeUuid);
                }
            };
        } else {
            int numTracks = getTrackCount();
            for (int i = 0; i < numTracks; ++i) {
                Map<String, Object> trackFormatMap = getTrackFormatNative(i);
                if (!trackFormatMap.containsKey("crypto-key")) {
                    continue;
                }
                ByteBuffer buf = (ByteBuffer) trackFormatMap.get("crypto-key");
                buf.rewind();
                final byte[] data = new byte[buf.remaining()];
                buf.get(data);
                return new DrmInitData() {
                    public SchemeInitData get(UUID schemeUuid) {
                        return new DrmInitData.SchemeInitData("webm", data);
                    }
                };
            }
        }
        return null;
    }

    /**
     * Get the PSSH info if present.
     * @return a map of uuid-to-bytes, with the uuid specifying
     * the crypto scheme, and the bytes being the data specific to that scheme.
     * This can be {@code null} if the source does not contain PSSH info.
     */
    @Nullable
    public Map<UUID, byte[]> getPsshInfo() {
        Map<UUID, byte[]> psshMap = null;
        Map<String, Object> formatMap = getFileFormatNative();
        if (formatMap != null && formatMap.containsKey("pssh")) {
            ByteBuffer rawpssh = (ByteBuffer) formatMap.get("pssh");
            rawpssh.order(ByteOrder.nativeOrder());
            rawpssh.rewind();
            formatMap.remove("pssh");
            // parse the flat pssh bytebuffer into something more manageable
            psshMap = new HashMap<UUID, byte[]>();
            while (rawpssh.remaining() > 0) {
                rawpssh.order(ByteOrder.BIG_ENDIAN);
                long msb = rawpssh.getLong();
                long lsb = rawpssh.getLong();
                UUID uuid = new UUID(msb, lsb);
                rawpssh.order(ByteOrder.nativeOrder());
                int datalen = rawpssh.getInt();
                byte [] psshdata = new byte[datalen];
                rawpssh.get(psshdata);
                psshMap.put(uuid, psshdata);
            }
        }
        return psshMap;
    }

    @NonNull
    private native Map<String, Object> getFileFormatNative();

    /**
     * Get the track format at the specified index.
     *
     * More detail on the representation can be found at {@link android.media.MediaCodec}
     * <p>
     * The following table summarizes support for format keys across android releases:
     *
     * <table style="width: 0%">
     *  <thead>
     *   <tr>
     *    <th rowspan=2>OS Version(s)</th>
     *    <td colspan=3>{@code MediaFormat} keys used for</th>
     *   </tr><tr>
     *    <th>All Tracks</th>
     *    <th>Audio Tracks</th>
     *    <th>Video Tracks</th>
     *   </tr>
     *  </thead>
     *  <tbody>
     *   <tr>
     *    <td>{@link android.os.Build.VERSION_CODES#JELLY_BEAN}</td>
     *    <td rowspan=8>{@link MediaFormat#KEY_MIME},<br>
     *        {@link MediaFormat#KEY_DURATION},<br>
     *        {@link MediaFormat#KEY_MAX_INPUT_SIZE}</td>
     *    <td rowspan=5>{@link MediaFormat#KEY_SAMPLE_RATE},<br>
     *        {@link MediaFormat#KEY_CHANNEL_COUNT},<br>
     *        {@link MediaFormat#KEY_CHANNEL_MASK},<br>
     *        gapless playback information<sup>.mp3, .mp4</sup>,<br>
     *        {@link MediaFormat#KEY_IS_ADTS}<sup>AAC if streaming</sup>,<br>
     *        codec-specific data<sup>AAC, Vorbis</sup></td>
     *    <td rowspan=2>{@link MediaFormat#KEY_WIDTH},<br>
     *        {@link MediaFormat#KEY_HEIGHT},<br>
     *        codec-specific data<sup>AVC, MPEG4</sup></td>
     *   </tr><tr>
     *    <td>{@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR1}</td>
     *   </tr><tr>
     *    <td>{@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR2}</td>
     *    <td rowspan=3>as above, plus<br>
     *        Pixel aspect ratio information<sup>AVC, *</sup></td>
     *   </tr><tr>
     *    <td>{@link android.os.Build.VERSION_CODES#KITKAT}</td>
     *   </tr><tr>
     *    <td>{@link android.os.Build.VERSION_CODES#KITKAT_WATCH}</td>
     *   </tr><tr>
     *    <td>{@link android.os.Build.VERSION_CODES#LOLLIPOP}</td>
     *    <td rowspan=2>as above, plus<br>
     *        {@link MediaFormat#KEY_BIT_RATE}<sup>AAC</sup>,<br>
     *        codec-specific data<sup>Opus</sup></td>
     *    <td rowspan=2>as above, plus<br>
     *        {@link MediaFormat#KEY_ROTATION}<sup>.mp4</sup>,<br>
     *        {@link MediaFormat#KEY_BIT_RATE}<sup>MPEG4</sup>,<br>
     *        codec-specific data<sup>HEVC</sup></td>
     *   </tr><tr>
     *    <td>{@link android.os.Build.VERSION_CODES#LOLLIPOP_MR1}</td>
     *   </tr><tr>
     *    <td>{@link android.os.Build.VERSION_CODES#M}</td>
     *    <td>as above, plus<br>
     *        gapless playback information<sup>Opus</sup></td>
     *    <td>as above, plus<br>
     *        {@link MediaFormat#KEY_FRAME_RATE} (integer)</td>
     *   </tr><tr>
     *    <td>{@link android.os.Build.VERSION_CODES#N}</td>
     *    <td>as above, plus<br>
     *        {@link MediaFormat#KEY_TRACK_ID},<br>
     *        <!-- {link MediaFormat#KEY_MAX_BIT_RATE}<sup>#, .mp4</sup>,<br> -->
     *        {@link MediaFormat#KEY_BIT_RATE}<sup>#, .mp4</sup></td>
     *    <td>as above, plus<br>
     *        {@link MediaFormat#KEY_PCM_ENCODING},<br>
     *        {@link MediaFormat#KEY_PROFILE}<sup>AAC</sup></td>
     *    <td>as above, plus<br>
     *        {@link MediaFormat#KEY_HDR_STATIC_INFO}<sup>#, .webm</sup>,<br>
     *        {@link MediaFormat#KEY_COLOR_STANDARD}<sup>#</sup>,<br>
     *        {@link MediaFormat#KEY_COLOR_TRANSFER}<sup>#</sup>,<br>
     *        {@link MediaFormat#KEY_COLOR_RANGE}<sup>#</sup>,<br>
     *        {@link MediaFormat#KEY_PROFILE}<sup>MPEG2, H.263, MPEG4, AVC, HEVC, VP9</sup>,<br>
     *        {@link MediaFormat#KEY_LEVEL}<sup>H.263, MPEG4, AVC, HEVC, VP9</sup>,<br>
     *        codec-specific data<sup>VP9</sup></td>
     *   </tr>
     *   <tr>
     *    <td colspan=4>
     *     <p class=note><strong>Notes:</strong><br>
     *      #: container-specified value only.<br>
     *      .mp4, .webm&hellip;: for listed containers<br>
     *      MPEG4, AAC&hellip;: for listed codecs
     *    </td>
     *   </tr><tr>
     *    <td colspan=4>
     *     <p class=note>Note that that level information contained in the container many times
     *     does not match the level of the actual bitstream. You may want to clear the level using
     *     {@code MediaFormat.setString(KEY_LEVEL, null)} before using the track format to find a
     *     decoder that can play back a particular track.
     *    </td>
     *   </tr><tr>
     *    <td colspan=4>
     *     <p class=note><strong>*Pixel (sample) aspect ratio</strong> is returned in the following
     *     keys. The display width can be calculated for example as:
     *     <p align=center>
     *     display-width = display-height * crop-width / crop-height * sar-width / sar-height
     *    </td>
     *   </tr><tr>
     *    <th>Format Key</th><th>Value Type</th><th colspan=2>Description</th>
     *   </tr><tr>
     *    <td>{@code "sar-width"}</td><td>Integer</td><td colspan=2>Pixel aspect ratio width</td>
     *   </tr><tr>
     *    <td>{@code "sar-height"}</td><td>Integer</td><td colspan=2>Pixel aspect ratio height</td>
     *   </tr>
     *  </tbody>
     * </table>
     *
     */
    @NonNull
    public MediaFormat getTrackFormat(int index) {
        return new MediaFormat(getTrackFormatNative(index));
    }

    @NonNull
    private native Map<String, Object> getTrackFormatNative(int index);

    /**
     * Subsequent calls to {@link #readSampleData}, {@link #getSampleTrackIndex} and
     * {@link #getSampleTime} only retrieve information for the subset of tracks
     * selected.
     * Selecting the same track multiple times has no effect, the track is
     * only selected once.
     */
    public native void selectTrack(int index);

    /**
     * Subsequent calls to {@link #readSampleData}, {@link #getSampleTrackIndex} and
     * {@link #getSampleTime} only retrieve information for the subset of tracks
     * selected.
     */
    public native void unselectTrack(int index);

    /**
     * If possible, seek to a sync sample at or before the specified time
     */
    public static final int SEEK_TO_PREVIOUS_SYNC       = 0;
    /**
     * If possible, seek to a sync sample at or after the specified time
     */
    public static final int SEEK_TO_NEXT_SYNC           = 1;
    /**
     * If possible, seek to the sync sample closest to the specified time
     */
    public static final int SEEK_TO_CLOSEST_SYNC        = 2;

    /** @hide */
    @IntDef({
        SEEK_TO_PREVIOUS_SYNC,
        SEEK_TO_NEXT_SYNC,
        SEEK_TO_CLOSEST_SYNC,
    })
    @Retention(RetentionPolicy.SOURCE)
    public @interface SeekMode {}

    /**
     * All selected tracks seek near the requested time according to the
     * specified mode.
     */
    public native void seekTo(long timeUs, @SeekMode int mode);

    /**
     * Advance to the next sample. Returns false if no more sample data
     * is available (end of stream).
     *
     * When extracting a local file, the behaviors of {@link #advance} and
     * {@link #readSampleData} are undefined in presence of concurrent
     * writes to the same local file; more specifically, end of stream
     * could be signalled earlier than expected.
     */
    public native boolean advance();

    /**
     * Retrieve the current encoded sample and store it in the byte buffer
     * starting at the given offset.
     * <p>
     * <b>Note:</b>As of API 21, on success the position and limit of
     * {@code byteBuf} is updated to point to the data just read.
     * @param byteBuf the destination byte buffer
     * @return the sample size (or -1 if no more samples are available).
     */
    public native int readSampleData(@NonNull ByteBuffer byteBuf, int offset);

    /**
     * Returns the track index the current sample originates from (or -1
     * if no more samples are available)
     */
    public native int getSampleTrackIndex();

    /**
     * Returns the current sample's presentation time in microseconds.
     * or -1 if no more samples are available.
     */
    public native long getSampleTime();

    // Keep these in sync with their equivalents in NuMediaExtractor.h
    /**
     * The sample is a sync sample (or in {@link MediaCodec}'s terminology
     * it is a key frame.)
     *
     * @see MediaCodec#BUFFER_FLAG_KEY_FRAME
     */
    public static final int SAMPLE_FLAG_SYNC      = 1;

    /**
     * The sample is (at least partially) encrypted, see also the documentation
     * for {@link android.media.MediaCodec#queueSecureInputBuffer}
     */
    public static final int SAMPLE_FLAG_ENCRYPTED = 2;

    /**
     * This indicates that the buffer only contains part of a frame,
     * and the decoder should batch the data until a buffer without
     * this flag appears before decoding the frame.
     *
     * @see MediaCodec#BUFFER_FLAG_PARTIAL_FRAME
     */
    public static final int SAMPLE_FLAG_PARTIAL_FRAME = 4;

    /** @hide */
    @IntDef(
        flag = true,
        value = {
            SAMPLE_FLAG_SYNC,
            SAMPLE_FLAG_ENCRYPTED,
            SAMPLE_FLAG_PARTIAL_FRAME,
    })
    @Retention(RetentionPolicy.SOURCE)
    public @interface SampleFlag {}

    /**
     * Returns the current sample's flags.
     */
    @SampleFlag
    public native int getSampleFlags();

    /**
     * If the sample flags indicate that the current sample is at least
     * partially encrypted, this call returns relevant information about
     * the structure of the sample data required for decryption.
     * @param info The android.media.MediaCodec.CryptoInfo structure
     *             to be filled in.
     * @return true iff the sample flags contain {@link #SAMPLE_FLAG_ENCRYPTED}
     */
    public native boolean getSampleCryptoInfo(@NonNull MediaCodec.CryptoInfo info);

    /**
     * Returns an estimate of how much data is presently cached in memory
     * expressed in microseconds. Returns -1 if that information is unavailable
     * or not applicable (no cache).
     */
    public native long getCachedDuration();

    /**
     * Returns true iff we are caching data and the cache has reached the
     * end of the data stream (for now, a future seek may of course restart
     * the fetching of data).
     * This API only returns a meaningful result if {@link #getCachedDuration}
     * indicates the presence of a cache, i.e. does NOT return -1.
     */
    public native boolean hasCacheReachedEndOfStream();

    /**
     *  Return Metrics data about the current media container.
     *
     * @return a {@link PersistableBundle} containing the set of attributes and values
     * available for the media container being handled by this instance
     * of MediaExtractor.
     * The attributes are descibed in {@link MetricsConstants}.
     *
     *  Additional vendor-specific fields may also be present in
     *  the return value.
     */

    public PersistableBundle getMetrics() {
        PersistableBundle bundle = native_getMetrics();
        return bundle;
    }

    private native PersistableBundle native_getMetrics();

    private static native final void native_init();
    private native final void native_setup();
    private native final void native_finalize();

    static {
        System.loadLibrary("media_jni");
        native_init();
    }

    private MediaCas mMediaCas;

    private long mNativeContext;

    public final static class MetricsConstants
    {
        private MetricsConstants() {}

        /**
         * Key to extract the container format
         * from the {@link MediaExtractor#getMetrics} return value.
         * The value is a String.
         */
        public static final String FORMAT = "android.media.mediaextractor.fmt";

        /**
         * Key to extract the container MIME type
         * from the {@link MediaExtractor#getMetrics} return value.
         * The value is a String.
         */
        public static final String MIME_TYPE = "android.media.mediaextractor.mime";

        /**
         * Key to extract the number of tracks in the container
         * from the {@link MediaExtractor#getMetrics} return value.
         * The value is an integer.
         */
        public static final String TRACKS = "android.media.mediaextractor.ntrk";

    }

}