java.nio.ByteBuffer.arrayOffset 处的 java.lang.UnsupportedOperationException？

Question

I need get the bitmap from IFrameCallback which was functioned to deal with the frame from a UVCCamera preview, but there's comes the exception:

java.lang.UnsupportedOperationException at java.nio.ByteBuffer.arrayOffset

private final IFrameCallback callback = new IFrameCallback() {
    @override
    public void onFrame(final ByteBuffer frame) {
        new Thread(new Runnable() {
            byte[] bytes = new byte[frame.remaining()];
            frame.get(bytes);

            if(bytes.length > 0) {
                int offset = frame.arrayOffset();
                Bitmap bitmap = BitmapFactory.decodeByteArray(bytes, offset, bytes.length - offset);
                ......
            }
        }).start();
    }
}

or if I use createBitmap instead of decodeByteArray , I got this exception:

java.lang.RuntimeException: Buffer not large enough for pixels at android.graphics.Bitmap.copyPixelsFromBuffer

private final IFrameCallback callback = new IFrameCallback() {
    @override
    public void onFrame(final ByteBuffer frame) {
        new Thread(new Runnable() {
            Bitmap bitmap = Bitmap.createBitmap(UVCCamera.DEFAULT_PREVIEW_WIDTH, UVCCamera.DEFAULT_PREVIEW_HEIGHT, Bitmap.Config.ARGB_8888);
            bitmap.copyPixelsFromBuffer(frame);
            ......
        }).start();
    }
}

Because the preview size is 1280 x 720 , so the problem of RuntimeException can be ignored.

Is there any ideas about the first exception to get the arrayOffset from ByteBuffer ?

PS: I know

UnsupportedOperationException - If this buffer is not backed by an accessible array

My point is: is there any other ways to get the arrayOffset , or if can't do that and how to solve the RuntimeException?

Answer 1

Well, since there's no a good solution, I had changed the way to get the bitmap from IFrameCallback .

Because I had applied the UVCCamera.PIXEL_FORMAT_NV21 format to the UVCCamera :

uvcCamera.setFrameCallback(frameCallback, UVCCamera.PIXEL_FORMAT_NV21);

So, I can get the bitmap just transform YuvImage :

private ChannelBufferOutputStream stream = new ChannelBufferOutputStream(MessageBuffers.dynamicBuffer());
......
private final IFrameCallback callback = new IFrameCallback() {
    @override
    public void onFrame(final ByteBuffer frame) {
        new Thread(new Runnable() {
            @override
            public void run() {
                byte[] bytes = new byte[frame.remaining()];
                frame.get(bytes);

                if(bytes.length > 0) {
                    YuvImage yuvImage = new YuvImage(bytes, ImageFormat.NV21, UVCCamera.DEFAULT_PREVIEW_WIDTH, UVCCamera.DEFAULT_PREVIEW_HEIGHT, null);
                    bytes = null;

                    if(yuvImage.getYuvData().length > 0) {
                        yuvImage.compressToJpeg(new Rect(0, 0, yuvImage.getWidth(), yuvImage.getHeight()), 80, stream);
                        Bitmap bitmap = BitmapFactory.decodeByteArray(stream.buffer().array(), 0, stream.buffer().array().length);
                        ......
                    }
                }
            }
        }).start();
    }
}