android/media/MediaMuxer.java

/*
 * Copyright (C) 2013 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.media.MediaCodec.BufferInfo;

import dalvik.system.CloseGuard;

import java.io.File;
import java.io.FileDescriptor;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.Map;

/**
 * MediaMuxer facilitates muxing elementary streams. Currently only supports an
 * mp4 file as the output and at most one audio and/or one video elementary
 * stream.
 * <p>
 * It is generally used like this:
 *
 * <pre>
 * MediaMuxer muxer = new MediaMuxer(...);
 * MediaFormat audioFormat = new MediaFormat(...);
 * MediaFormat videoFormat = new MediaFormat(...);
 * int audioTrackIndex = muxer.addTrack(audioFormat);
 * int videoTrackIndex = muxer.addTrack(videoFormat);
 * ByteBuffer inputBuffer = ByteBuffer.allocate(...);
 * muxer.start();
 * while(inputBuffer has new data) {
 *   if (new data is audio sample) {
 *     muxer.writeSampleData(audioTrackIndex, inputBuffer, ...);
 *   } else if (new data is video sample) {
 *     muxer.writeSampleData(videoTrackIndex, inputBuffer, ...);
 *   }
 * }
 * muxer.stop();
 * muxer.release();
 * </pre>
 */

final public class MediaMuxer {

    private int mNativeContext;

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

    /**
     * Defines the output format. These constants are used with constructor.
     */
    public static final class OutputFormat {
        /* Do not change these values without updating their counterparts
         * in include/media/stagefright/MediaMuxer.h!
         */
        private OutputFormat() {}
        /** MPEG4 media file format*/
        public static final int MUXER_OUTPUT_MPEG_4 = 0;
    };

    // All the native functions are listed here.
    private static native int nativeSetup(FileDescriptor fd, int format);
    private static native void nativeRelease(int nativeObject);
    private static native void nativeStart(int nativeObject);
    private static native void nativeStop(int nativeObject);
    private static native int nativeAddTrack(int nativeObject, String[] keys,
            Object[] values);
    private static native void nativeSetOrientationHint(int nativeObject,
            int degrees);
    private static native void nativeWriteSampleData(int nativeObject,
            int trackIndex, ByteBuffer byteBuf,
            int offset, int size, long presentationTimeUs, int flags);

    // Muxer internal states.
    private static final int MUXER_STATE_UNINITIALIZED  = -1;
    private static final int MUXER_STATE_INITIALIZED    = 0;
    private static final int MUXER_STATE_STARTED        = 1;
    private static final int MUXER_STATE_STOPPED        = 2;

    private int mState = MUXER_STATE_UNINITIALIZED;

    private final CloseGuard mCloseGuard = CloseGuard.get();
    private int mLastTrackIndex = -1;

    private int mNativeObject;

    /**
     * Constructor.
     * Creates a media muxer that writes to the specified path.
     * @param path The path of the output media file.
     * @param format The format of the output media file.
     * @see android.media.MediaMuxer.OutputFormat
     * @throws IOException if failed to open the file for write
     */
    public MediaMuxer(String path, int format) throws IOException {
        if (path == null) {
            throw new IllegalArgumentException("path must not be null");
        }
        if (format != OutputFormat.MUXER_OUTPUT_MPEG_4) {
            throw new IllegalArgumentException("format is invalid");
        }
        FileOutputStream fos = null;
        try {
            File file = new File(path);
            fos = new FileOutputStream(file);
            FileDescriptor fd = fos.getFD();
            mNativeObject = nativeSetup(fd, format);
            mState = MUXER_STATE_INITIALIZED;
            mCloseGuard.open("release");
        } finally {
            if (fos != null) {
                fos.close();
            }
        }
    }

    /**
     * Sets the orientation hint for output video playback.
     * <p>This method should be called before {@link #start}. Calling this
     * method will not rotate the video frame when muxer is generating the file,
     * but add a composition matrix containing the rotation angle in the output
     * video if the output format is
     * {@link OutputFormat#MUXER_OUTPUT_MPEG_4} so that a video player can
     * choose the proper orientation for playback. Note that some video players
     * may choose to ignore the composition matrix in a video during playback.
     * By default, the rotation degree is 0.</p>
     * @param degrees the angle to be rotated clockwise in degrees.
     * The supported angles are 0, 90, 180, and 270 degrees.
     */
    public void setOrientationHint(int degrees) {
        if (degrees != 0 && degrees != 90  && degrees != 180 && degrees != 270) {
            throw new IllegalArgumentException("Unsupported angle: " + degrees);
        }
        if (mState == MUXER_STATE_INITIALIZED) {
            nativeSetOrientationHint(mNativeObject, degrees);
        } else {
            throw new IllegalStateException("Can't set rotation degrees due" +
                    " to wrong state.");
        }
    }

    /**
     * Starts the muxer.
     * <p>Make sure this is called after {@link #addTrack} and before
     * {@link #writeSampleData}.</p>
     */
    public void start() {
        if (mNativeObject == 0) {
            throw new IllegalStateException("Muxer has been released!");
        }
        if (mState == MUXER_STATE_INITIALIZED) {
            nativeStart(mNativeObject);
            mState = MUXER_STATE_STARTED;
        } else {
            throw new IllegalStateException("Can't start due to wrong state.");
        }
    }

    /**
     * Stops the muxer.
     * <p>Once the muxer stops, it can not be restarted.</p>
     */
    public void stop() {
        if (mState == MUXER_STATE_STARTED) {
            nativeStop(mNativeObject);
            mState = MUXER_STATE_STOPPED;
        } else {
            throw new IllegalStateException("Can't stop due to wrong state.");
        }
    }

    @Override
    protected void finalize() throws Throwable {
        try {
            if (mCloseGuard != null) {
                mCloseGuard.warnIfOpen();
            }
            if (mNativeObject != 0) {
                nativeRelease(mNativeObject);
                mNativeObject = 0;
            }
        } finally {
            super.finalize();
        }
    }

    /**
     * Adds a track with the specified format.
     * @param format The media format for the track.
     * @return The track index for this newly added track, and it should be used
     * in the {@link #writeSampleData}.
     */
    public int addTrack(MediaFormat format) {
        if (format == null) {
            throw new IllegalArgumentException("format must not be null.");
        }
        if (mState != MUXER_STATE_INITIALIZED) {
            throw new IllegalStateException("Muxer is not initialized.");
        }
        if (mNativeObject == 0) {
            throw new IllegalStateException("Muxer has been released!");
        }
        int trackIndex = -1;
        // Convert the MediaFormat into key-value pairs and send to the native.
        Map<String, Object> formatMap = format.getMap();

        String[] keys = null;
        Object[] values = null;
        int mapSize = formatMap.size();
        if (mapSize > 0) {
            keys = new String[mapSize];
            values = new Object[mapSize];
            int i = 0;
            for (Map.Entry<String, Object> entry : formatMap.entrySet()) {
                keys[i] = entry.getKey();
                values[i] = entry.getValue();
                ++i;
            }
            trackIndex = nativeAddTrack(mNativeObject, keys, values);
        } else {
            throw new IllegalArgumentException("format must not be empty.");
        }

        // Track index number is expected to incremented as addTrack succeed.
        // However, if format is invalid, it will get a negative trackIndex.
        if (mLastTrackIndex >= trackIndex) {
            throw new IllegalArgumentException("Invalid format.");
        }
        mLastTrackIndex = trackIndex;
        return trackIndex;
    }

    /**
     * Writes an encoded sample into the muxer.
     * <p>The application needs to make sure that the samples are written into
     * the right tracks. Also, it needs to make sure the samples for each track
     * are written in chronological order (e.g. in the order they are provided
     * by the encoder.)</p>
     * @param byteBuf The encoded sample.
     * @param trackIndex The track index for this sample.
     * @param bufferInfo The buffer information related to this sample.
     * MediaMuxer uses the flags provided in {@link MediaCodec.BufferInfo},
     * to signal sync frames.
     */
    public void writeSampleData(int trackIndex, ByteBuffer byteBuf,
            BufferInfo bufferInfo) {
        if (trackIndex < 0 || trackIndex > mLastTrackIndex) {
            throw new IllegalArgumentException("trackIndex is invalid");
        }

        if (byteBuf == null) {
            throw new IllegalArgumentException("byteBuffer must not be null");
        }

        if (bufferInfo == null) {
            throw new IllegalArgumentException("bufferInfo must not be null");
        }
        if (bufferInfo.size < 0 || bufferInfo.offset < 0
                || (bufferInfo.offset + bufferInfo.size) > byteBuf.capacity()
                || bufferInfo.presentationTimeUs < 0) {
            throw new IllegalArgumentException("bufferInfo must specify a" +
                    " valid buffer offset, size and presentation time");
        }

        if (mNativeObject == 0) {
            throw new IllegalStateException("Muxer has been released!");
        }

        if (mState != MUXER_STATE_STARTED) {
            throw new IllegalStateException("Can't write, muxer is not started");
        }

        nativeWriteSampleData(mNativeObject, trackIndex, byteBuf,
                bufferInfo.offset, bufferInfo.size,
                bufferInfo.presentationTimeUs, bufferInfo.flags);
    }

    /**
     * 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 void release() {
        if (mState == MUXER_STATE_STARTED) {
            stop();
        }
        if (mNativeObject != 0) {
            nativeRelease(mNativeObject);
            mNativeObject = 0;
            mCloseGuard.close();
        }
        mState = MUXER_STATE_UNINITIALIZED;
    }
}