Vladimir Kulyk Vladimir Kulyk - 1 month ago 57
Android Question

Android Camera2 API YUV_420_888 to JPEG

I'm getting preview frames using OnImageAvailableListener:


@Override
public void onImageAvailable(ImageReader reader) {
Image image = null;
try {
image = reader.acquireLatestImage();
Image.Plane[] planes = image.getPlanes();
ByteBuffer buffer = planes[0].getBuffer();
byte[] data = new byte[buffer.capacity()];
buffer.get(data);
//data.length=332803; width=3264; height=2448
Log.e(TAG, "data.length=" + data.length + "; width=" + image.getWidth() + "; height=" + image.getHeight());
//TODO data processing
} catch (Exception e) {
e.printStackTrace();
}
if (image != null) {
image.close();
}
}


Each time length of data is different but image width and height are the same.

Main problem:
data.length
is too small for such resolution as 3264x2448.

Size of data array should be 3264*2448=7,990,272, not 300,000 - 600,000.

What is wrong?




imageReader = ImageReader.newInstance(3264, 2448, ImageFormat.JPEG, 5);

Answer

I solved this problem by using YUV_420_888 image format and converting it to JPEG image format manually.

imageReader = ImageReader.newInstance(MAX_PREVIEW_WIDTH, MAX_PREVIEW_HEIGHT, 
                                      ImageFormat.YUV_420_888, 5);
imageReader.setOnImageAvailableListener(this, null);

Surface imageSurface = imageReader.getSurface();
List<Surface> surfaceList = new ArrayList<>();
//...add other surfaces
previewRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
previewRequestBuilder.addTarget(imageSurface);
            surfaceList.add(imageSurface);
cameraDevice.createCaptureSession(surfaceList,
                    new CameraCaptureSession.StateCallback() {
//...implement onConfigured, onConfigureFailed for StateCallback
}, null);

@Override
public void onImageAvailable(ImageReader reader) {
    Image image = reader.acquireLatestImage();
    if (image != null) {
        //converting to JPEG
        byte[] jpegData = ImageUtils.imageToByteArray(image);
        //write to file (for example ..some_path/frame.jpg)
        FileManager.writeFrame(FILE_NAME, jpegData);
    }
}

public final class ImageUtil {

    public static byte[] imageToByteArray(Image image) {
        byte[] data = null;
        if (image.getFormat() == ImageFormat.JPEG) {
            Image.Plane[] planes = image.getPlanes();
            ByteBuffer buffer = planes[0].getBuffer();
            data = new byte[buffer.capacity()];
            buffer.get(data);
            return data;
        } else if (image.getFormat() == ImageFormat.YUV_420_888) {
            data = NV21toJPEG(
                    YUV_420_888toNV21(image),
                    image.getWidth(), image.getHeight());
        }
        return data;
    }

    private static byte[] YUV_420_888toNV21(Image image) {
        byte[] nv21;
        ByteBuffer yBuffer = image.getPlanes()[0].getBuffer();
        ByteBuffer uBuffer = image.getPlanes()[1].getBuffer();
        ByteBuffer vBuffer = image.getPlanes()[2].getBuffer();

        int ySize = yBuffer.remaining();
        int uSize = uBuffer.remaining();
        int vSize = vBuffer.remaining();

        nv21 = new byte[ySize + uSize + vSize];

        //U and V are swapped
        yBuffer.get(nv21, 0, ySize);
        vBuffer.get(nv21, ySize, vSize);
        uBuffer.get(nv21, ySize + vSize, uSize);

        return nv21;
    }

    private static byte[] NV21toJPEG(byte[] nv21, int width, int height) {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        YuvImage yuv = new YuvImage(nv21, ImageFormat.NV21, width, height, null);
        yuv.compressToJpeg(new Rect(0, 0, width, height), 100, out);
        return out.toByteArray();
    }
}

public final class FileManager {
    public static void writeFrame(String fileName, byte[] data) {
        try {
            BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(fileName));
            bos.write(data);
            bos.flush();
            bos.close();
//            Log.e(TAG, "" + data.length + " bytes have been written to " + filesDir + fileName + ".jpg");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}