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.content.ContentResolver;
import android.content.Context;
import android.content.res.AssetFileDescriptor;
import android.media.MediaCodec;
import android.net.Uri;
import java.io.FileDescriptor;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.Map;

/**
 * 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.countTracks();
 * for (int i = 0; i &lt; numTracks; ++i) {
 *   Map%lt;String, Object&gt; format = extractor.getTrackFormat(i);
 *   String mime = (String)format.get("mime");
 *   if (weAreInterestedInThisTrack) {
 *     extractor.selectTrack(i);
 *   }
 * }
 * ByteBuffer inputBuffer = ByteBuffer.allocate(...)
 * while (extractor.readSampleData(inputBuffer, ...) &gt;= 0) {
 *   int trackIndex = extractor.getTrackIndex();
 *   long presentationTimeUs = extractor.getSampleTime();
 *   ...
 *   extractor.advance();
 * }
 *
 * extractor.release();
 * extractor = null;
 * </pre>
*/
final public class MediaExtractor {
    public MediaExtractor() {
        native_setup();
    }

    /**
     * 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.
     * @param headers the headers to be sent together with the request for the data
     */
    public final void setDataSource(
            Context context, Uri uri, 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
     * @param headers the headers associated with the http request for the stream you want to play
     */
    public final void setDataSource(String path, Map<String, String> headers) {
        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;
            }
        }
        setDataSource(path, keys, values);
    }

    private native final void setDataSource(
            String path, String[] keys, String[] values);

    /**
     * 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)}.
     */
    public final void setDataSource(String path) {
        setDataSource(path, null, null);
    }

    /**
     * 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(FileDescriptor fd) {
        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(
            FileDescriptor fd, long offset, long length);

    @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 int countTracks();

    /** Get the track format at the specified index.
      * More detail on the representation can be found at {@link android.media.MediaCodec}
    */
    public native Map<String, Object> getTrackFormat(int index);

    /** Subsequent calls to {@link #readSampleData}, {@link #getSampleTrackIndex} and
     *  {@link #getSampleTime} only retrieve information for the subset of tracks
     *  selected by the call below.
     *  Selecting the same track multiple times has no effect, the track
     *  only selected once.
     *  Media data will be returned in the order of their timestamps.
    */
    public native void selectTrack(int index);

    /** All selected tracks seek near the requested time. The next sample
     *  returned for each selected track will be a sync sample.
    */
    public native void seekTo(long timeUs);

    /** Advance to the next sample. Returns false if no more sample data
     *  is available (end of stream).
     */
    public native boolean advance();

    /** Retrieve the current encoded sample and store it in the byte buffer
     *  starting at the given offset. Returns the sample size (or -1 if
     *  no more samples are available).
    */
    public native int readSampleData(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 */
    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;

    /** Returns the current sample's flags. */
    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(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();

    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 int mNativeContext;
}