Android: how to display camera preview with callback?

Question

What I need to do is quite simple, I want to manually display preview from camera using camera callback and I want to get at least 15fps on a real device. I don\'t even need

Answer 1

I'm working on exactly the same issue, but haven't got quite as far as you have.

Have you considered drawing the pixels directly to the canvas without encoding them to JPEG first? Inside the OpenCV kit http://sourceforge.net/projects/opencvlibrary/files/opencv-android/2.3.1/OpenCV-2.3.1-android-bin.tar.bz2/download (which doesn't actually use opencv; don't worry), there's a project called tutorial-0-androidcamera that demonstrates converting the YUV pixels to RGB and then writing them directly to a bitmap.

The relevant code is essentially:

public void onPreviewFrame(byte[] data, Camera camera, int width, int height) {
    int frameSize = width*height;
    int[] rgba = new int[frameSize+1];

    // Convert YUV to RGB
    for (int i = 0; i < height; i++)
        for (int j = 0; j < width; j++) {
            int y = (0xff & ((int) data[i * width + j]));
            int u = (0xff & ((int) data[frameSize + (i >> 1) * width + (j & ~1) + 0]));
            int v = (0xff & ((int) data[frameSize + (i >> 1) * width + (j & ~1) + 1]));
            y = y < 16 ? 16 : y;

            int r = Math.round(1.164f * (y - 16) + 1.596f * (v - 128));
            int g = Math.round(1.164f * (y - 16) - 0.813f * (v - 128) - 0.391f * (u - 128));
            int b = Math.round(1.164f * (y - 16) + 2.018f * (u - 128));

            r = r < 0 ? 0 : (r > 255 ? 255 : r);
            g = g < 0 ? 0 : (g > 255 ? 255 : g);
            b = b < 0 ? 0 : (b > 255 ? 255 : b);

            rgba[i * width + j] = 0xff000000 + (b << 16) + (g << 8) + r;
        }

    Bitmap bmp = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
    bmp.setPixels(rgba, 0/* offset */, width /* stride */, 0, 0, width, height);
    Canvas canvas = mHolder.lockCanvas();
    if (canvas != null) {
        canvas.drawBitmap(bmp, (canvas.getWidth() - width) / 2, (canvas.getHeight() - height) / 2, null);
        mHolder.unlockCanvasAndPost(canvas);
    } else {
        Log.w(TAG, "Canvas is null!");
    }
    bmp.recycle();
}

Of course you'd have to adapt it to meet your needs (ex. not allocating rgba each frame), but it might be a start. I'd love to see if it works for you or not -- i'm still fighting problems orthogonal to yours at the moment.