How to encode non-camera video in Android

I am working on an android application in which a video is dynamically generated by compositing a sequence of animation frames. I tried to use the Android Media Recorder API for this but have not found a way to get it to accept a non-camera source as input. I have been attempting to use a FFMPEG port (based on the Rockplayer build) but am running into difficulties with missing functions since I am using it as an encoder, not a decoder.

The iPhone version of this app uses AVAssetWriter from the AVFoundation framework.

Is there an easier way to do this or am I stuck slugging it out with FF开发者_开发知识库MPEG?

This may help (see the note on resolution though):-

How to encode using the FFMpeg in Android (using H263)

I'm not sure if they did a custom build of ffmpeg, or not, if so they may be able to offer advice on porting a more feature complete version.

-Anthony

Opencv has ViewBase class which takes the input from the camera as a frame and represent the frame as a bitmap , you can extand the class View base and make it for your own use , even though installing opencv on the android isn't very easy.

When you extend SampleCvViewBase you will have the following function which you can use pretty much hard work but the best I can think of.

 @Override
protected Bitmap processFrame(VideoCapture capture) {


    capture.retrieve(picture, Highgui.CV_CAP_ANDROID_COLOR_FRAME_RGBA);



    if (Utils.matToBitmap(picture, bmp))
        return bmp;

    bmp.recycle();
    return null;


}

You can use a pure Java open source library called JCodec ( http://jcodec.org ).

It contains a simple yet working H.264 encoder and MP4 muxer. The class below uses JCodec low level API and should be what you need ( CORRECTED ):

    public class SequenceEncoder {
    private SeekableByteChannel ch;
    private Picture toEncode;
    private RgbToYuv420 transform;
    private H264Encoder encoder;
    private ArrayList<ByteBuffer> spsList;
    private ArrayList<ByteBuffer> ppsList;
    private CompressedTrack outTrack;
    private ByteBuffer _out;
    private int frameNo;
    private MP4Muxer muxer;

    public SequenceEncoder(File out) throws IOException {
        this.ch = NIOUtils.writableFileChannel(out);

        // Transform to convert between RGB and YUV
        transform = new RgbToYuv420(0, 0);

        // Muxer that will store the encoded frames
        muxer = new MP4Muxer(ch, Brand.MP4);

        // Add video track to muxer
        outTrack = muxer.addTrackForCompressed(TrackType.VIDEO, 25);

        // Allocate a buffer big enough to hold output frames
        _out = ByteBuffer.allocate(1920 * 1080 * 6);

        // Create an instance of encoder
        encoder = new H264Encoder();

        // Encoder extra data ( SPS, PPS ) to be stored in a special place of
        // MP4
        spsList = new ArrayList<ByteBuffer>();
        ppsList = new ArrayList<ByteBuffer>();

    }

    public void encodeImage(BufferedImage bi) throws IOException {
        if (toEncode == null) {
            toEncode = Picture.create(bi.getWidth(), bi.getHeight(), ColorSpace.YUV420);
        }

        // Perform conversion
        for (int i = 0; i < 3; i++)
            Arrays.fill(toEncode.getData()[i], 0);
        transform.transform(AWTUtil.fromBufferedImage(bi), toEncode);

        // Encode image into H.264 frame, the result is stored in '_out' buffer
        _out.clear();
        ByteBuffer result = encoder.encodeFrame(_out, toEncode);

        // Based on the frame above form correct MP4 packet
        spsList.clear();
        ppsList.clear();
        H264Utils.encodeMOVPacket(result, spsList, ppsList);

        // Add packet to video track
        outTrack.addFrame(new MP4Packet(result, frameNo, 25, 1, frameNo, true, null, frameNo, 0));

        frameNo++;
    }

    public void finish() throws IOException {
        // Push saved SPS/PPS to a special storage in MP4
        outTrack.addSampleEntry(H264Utils.createMOVSampleEntry(spsList, ppsList));

        // Write MP4 header and finalize recording
        muxer.writeHeader();
        NIOUtils.closeQuietly(ch);
    }

    public static void main(String[] args) throws IOException {
        SequenceEncoder encoder = new SequenceEncoder(new File("video.mp4"));
        for (int i = 1; i < 100; i++) {
            BufferedImage bi = ImageIO.read(new File(String.format("folder/img%08d.png", i)));
            encoder.encodeImage(bi);
        }
        encoder.finish();
    }
}

You can get JCodec jar from a project web-site.